First forms of life, which lacked the ability to synthesize their own nutrients.
Depend on outside food sources.
Origin of Life Building Blocks
Simple inorganic and organic compounds (in primitive seas) such as salts, methane, ammonia, hydrogen, and water.
Energy was present in the form of heat, electricity, solar radiation, including X-rays and ultraviolet light, cosmic rays and radioactivity.
Sugars, amino acids, purines, and pyrimidines.
After many years, these simple monomeric molecules combined to form a supply of macromolecules.
Evidence of Organic Synthesis
1953, Stanley L. Miller. UV radiation, heat or a combination of these to a mixture of methane, hydrogen, ammonia, and water could result in the formation of complex organic compounds. The 4 gases were continuously circulated past electrical discharges from tungsten elctrodes.
Organic compounds formed = urea, hydrogen, cyanide, acetic acid, and lactic acid
Formation of Primitive Cells
Coacervate droplets absorb and incorporate substances from environment, as well as have a definite internal structure. Developed on early earth and had properties normally associated with living organisms.
Few % turned into 1st primitive cells which had nucleic acid polymers and became capable of reproduction.
Life would have ceased to exist if not developed.
1st Autotrophs developed primitive photosynthetic pathways using solar energy to made carbohydrates from CO2 and water (O2 waste product).
Development of Aerobic Respiration
Addition of molecular oxygen to atmosphere converted it from reducing to oxidizing. Once molecular oxygen became the major component, both heterotrophs and autotrophs evolved the biochemical pathways of aerobic respiration.
(1 of 4 basic categories of living organisms)
Include chemosynthetic bacteria.
(1 of 4 basic categories of living organisms)
Include green plants and photoplankton.
(1 of 4 basic categories of living organisms)
(1 of 4 basic categories of living organisms)
Include amoebas, earthworms, and humans.
All living organisms are composed of...
Primarily of elements carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus.
Traces of magnesium, iodine, iron, calcium, and other minerals are also components of protoplasm (substance of life)
Compounds that do not contain the element carbon, including salts and HCl.
Made by living systems and contain carbon, including carbohydrates, lipids, proteins, and nucleic acids.
All living things are composed of cells
Cell is the basic functional unit of life
Cells arise only from pre-existing cells
Cells carry genetic info in the form of DNA... passed from parent cell to daughter cell
Compound Light Microscope
Uses 2 lenses or lens system.
Total magnification= Magnification of eyepiece x magnification of the object
In general used to study non-living specimens because require contracts between cells and cell structures (staining)
Phase Contrast Microscopy
Special type of light microscope that permits the study of living cells. Differences in refractive index are used to produce contrast and not kill the specimen.
Uses a beam of electrons to allow a thousandfold higher magnification than is possible with light microscope. Not possible for living specimens.
Can be used to separate cells or mixtures of cells without destroying them in the process. Denser parts, such as nuclei, endoplasmic reticulum, and mitochondria will sink to the bottom.
Cell Membrane (Plasma Membrane)
Encloses the cell and exhibits selective permeability. According to fluid mosaic model, cell membrane consists of phospholipid bilayer with proteins embedded throughout. As result, readily permeable to both small, nonpolar molecules (oxygen) and small, polar molecules (water). Small charged particles are usually able to cross the membrane through protein channels . Larger, charged molecules cross the membrane with carrier proteins.
Controls the activities of the cell, including cell division. It is surrounded by the nuclear membrane. Contains DNA
Protein production and are synthesized by the nucleolus. Free ribosomes are found in the cytoplasm
Network of membrane-enclosed spaces involved in the transport of materials throughout the cell, particularly those materials destined to be secreted by the cell.
Receives vesicles and their contents from the smooth ER, modifies them, repackages them into vesicles and distributes them to the cell surface by exocytosis.
Mitochondria are the sites of aerobic respiration within the cell and, hence the suppliers of energy. Each mitochondrion is bounded by an outer and inner phospholipid bilayer.
Most of the cell's metabolic activity occurs in the cytoplasm. Transport within the cytoplasm occurs by cyclosis (streaming movement within the cell).
Membrane-bound sacs involved in the transport and storage of materials that are ingested, secreted, processed , or digested by the cell. Vacuoles are larger than vesicles and are more likely to be found in plant than in animal cells.
Specialized microtubule involved in spindle organizaiton during cell division and are not bound by a membrane. Animal cells usually have a pair of centrioles that are oriented at right angles to each other and lie in a region called the centrosome. Plant cells do not contain centrioles.
Membrane-bound vesicles that contain hydrolytic enzymes involved in intracellular digestion. Lysosomes break down material ingested by the cell. An injured or dying tissue may "commit suicide" by rupturing the lysosome membrane and releasing its hydrolytic enzymes (autolysis)
Composed of microtubules and microfilaments, gives the cell mechanical support, maintains its shape, and functions in cell motility.
Net movement of dissolved particles down their concentration gradients- from a region of higher concentration to a region of lower concentration. This is a passive process that requires no external source of energy.
Simple diffusion of water from a region of lower solute concentration to a region of higher solute concentration.
When cytoplasm of a cell has a lower concentration of nonpenetrating solutes than the extracellular medium, the medium is said to be hypertonic. Water will flow out of the cell, causing cell to shrivel.
If extracellular environment is less concentrated than the cytoplasm of the cell, the extracellular medium is said to be hypotonic and water will flow into the cell, causing it to swell and lyse (burst).
Example: Red blood cells will burst if placed in distilled water.
(Passive Transport) Net movement of dissolved particles down their concentration gradient through special channels or via carrier proteins in the cell membrane. Does not require energy
Net movement of dissolved particles against their concentration gradient with the help of transport proteins. Requires energy.
Movement of particles due to kinetic energy spreads small, suspended particles throughout the cytoplasm of the cell.
Cyclosis or Streaming
Circular motion of cytoplasm around the cell transport molecules.
Provides channels throughout the cytoplasm and provides a direct continuous passageway from the plasma membrane to the nuclear membrane.
If cells are in direct or close contact with the external environment, diffusion can serve as a sufficient means of transport for food and oxygen from the environment to the cells. In large, more complex animals, diffusion is important for the transport of materials between cels and the interstitial fluid that bathes the cells.
Complex animals, whose cells are too far for diffusion, need this system. Generally involves vessels to transport fluid and a pump to drive the circulation.
Lower activation energy of a rxn
Increase the rate of the rxn
Do not affect the overall delta G of the rxn
Are not changed or consumed in the course of the rxn
The molecule upon which an enzyme acts. There is an area on each enzyme to which this substrate binds called the active site.
Two models: Lock and Key and Induced Fit Theory
Lock and Key Theory
The spatial structure of an enzyme's active site is exactly complementary to the spatial structure of its substrate. The two fit together like a lock and key.
The theory has been largely discounted.
Induced Fit Theory
Active site has a flexibility of shape. When the appropriate substrate comes in contact with the active site, the conformation of the active site changes to fit the substrate.
More widely accepted than Lock and Key Theory.
Most enzyme rxns are reversible. The product synthesized by an enzyme can be decomposed by the same enzyme.
Example: Enzyme that synthesizes maltose from glucose can hydrolyze maltose back to glucose.
What Effects Enzyme Reaction Rate
Temperature: As temp. increases, rxn rate increases until optimum temp is reached. Beyond optimal, enzyme is denatured and deactivated.
pH: Humans=7.2 :Exception is pepsin (pH=2) and pancreatic enzymes (pH=8.5)
Concentration: of Substrate and Enzyme
Function to digest large molecules into smaller parts.
In mult. cell. organisms, digestions can begin outside cells in the gut. Other hydrolytic rxns occur within cells.
Hydrolyzes lactose to the monosccharides glucose and galactose.
Degrade proteins to amino acids.
Break down lipids to fatty acids and glycerol.
(Include dehydrations) can be catalyzed by the enzymes as hydrolysis rxns but the directions of the rxns are reversed.
Synthesis is required for growth, repair, regulation, protection, and production of food reserves, such as fat and glycogen. The survival of a cell depends on its ability to ingest substances that it needs but cannot synthesize.
What many require the incorporation of a nonprotein molecule to become active. Can be metal cations (like Zn2+ or Fe2+) or small organic groups called coenzymes.
Cofactors that bind to enzyme by strong covalent bonds are called prosthetic groups.
Most cannot be synthesized by the body and are obtained through diet as vitamin derivatives.
The degradation oxidation of glucose occurs in two stages, glycolysis and cellular respiration.
First stage of glucose catabolism. A series of reactions that lead to the oxidative breakdown of glucose into two molecules of pyruvate, the production of ATP, and reduction of NAD+ to NADH.
Net Reaction for Glycolysis
Glucose + 2 ADP + 2 Pi + 2 NAD+ -->
2 Pyruvate + 2 ATP + 2 NADH + 2H+ +2 H2O
NAD+ must be regenerated for glycolsis to continue in the absence of O2. Accomplished by further reducing pyruvate into ethanol or lactic acid. Produces only 2 ATP per glucose molecule.
Commonly occurs only in yeast and some bacteria. The pyruvate produced in glycolysis is converted to ethanol. In this way, NAD+ is regenerated and glycolysis can continue.
Lactic Acid Fermentation
Occurs in certain fungi and bacteria, and in human muscle cells during strenuous activity. When oxygen supply to muscle cells lags behind rate of glucose catabolism, pyruvate generated is reduced to lactic acid.
Cellular Respiration Overall Definition
Most efficient catabolic pathway used by organisms to harvest the energy stored in glucose. Yields 36 to 38 ATP (glycolysis= 2 ATP/glucose).
Aerobic process where oxygen acts as the final acceptor of e- that are passed from carrier to carrier during the final stage of glucose oxidation.
Occurs in eukaryotic mitochondrion and are catalyzed by reaction-specific enzymes.
3 stages: pyruvate decarboxylation, citric acid cycle, electron transport chain
(Step 1 of Cellular Respiration)
Pyruvate formed during glycolysis is transported from the cytoplasm into the mitochondrial matrix where is loses a CO2 (decarboxylated) & acetyl group is transferred to coenzyme A to form acetyl CoA. NAD+ reduced to NADH.
Citric Acid Cycle aka Krebs Cycle
(Step 2 of Cellular Respiration)
2 Acetyl CoA + 6 NAD+ +2 FAD + 2 GDP + 2Pi + 4 H2O -->
4 CO2 + 6 NADH + 2FADH2 + 2 ATP + 4H+ +2 CoA
Electron Transport Chain
(Step 3 of Cellular Respiration)
Complex carrier mechanism located on the inside of the inner mitochondrial membrane. As electrons are transferred from carrier to carrier, free energy is released which is then used to form ATP.
Most molecules of ETC. Electron carriers that resemble hemoglobin in the structure of their active site. The functional unit contains a central iron atom, which is capable of undergoing a reversible redox reaction.
Each carrier is reduced as it accepts an electron and is then oxidized when it passes it on to the net carrier.
Degredation of 1 glucose molecule yields a net of 2 ATP from glycolysis and 1 ATP for each turn of the citric acid cycle. Thus, a total of 4 ATP are produced by substrate-level phosphorylation.
2 NADH of glycolysis yield 4 ATP, 8 other NADH yield 24 ATP, 2 FADH2 produce 4 ATP for a total of 32 ATP b oxidative phosphorylation.
Alternate Energy Sources
When glucose supplies are low the body uses these in preferential order: other carbohydrates, fats, and proteins. First converted to either glucose or glucose intermediates, which can then be degraded in the glycolytic pathway and the citric acid cycle.
Disaccharides are hydrolyzed to monosaccharides. Glycogen stored in the liver can be converted, when needed, into a glycolytic intermediate.
Stored in adipose tissue in the form of triglycerides. When needed they are hydrolyzed by lipases to fatty acids and glyercol and are carried by blood to other tissues for oxidation. Fats yield the highest number of ATP per gram.
Body degrades them only when not enough of other things are available.
Process by which a cell doubles its organelles and cytoplasm, replicates its DNA, & then divides in two. For unicellular organisms, its a means of reproduction. For multicellular organisms, its a method of growth, development, and replacement of worn-out cells.
Division and distribution of the cell's DNA to its two daughter cells such that each cell receives a complete copy of the original genome.
90% of cells time spent here. Each chromosome is replicated. After replication, chromosomes consist of 2 identical sister chromatids held together by a centromere.
Chromosomes condense & centriole pairs (in animals) separate and move towards opposite poles of the cell. The spindle apparatus forms between them and the nuclear membrane dissolves, allowing the spindle fibers to interact with the chromosomes.
Sister chromatids separate.
New nuclear membranes form.
In animal cells, a cleavage furrow forms and cell membrane indents along the equator of the cel and finally pinches through the cell, separating the two nuclei.
Differences in Plant Cell and Animal Cell Division
1. Plant cells lack centrioles. Spindle apparatus is synthesized by microtubule organizing centers.
2. Plant cells divide with a formation of a cell plate (not cleavage furrow, they are too rigid)
The process by which sex cells are produced. 2 divisions of primary sex cells resulting in four haploid cells called gametes.
Sexual reproduction differs from asexual (mitosis) because it involves 2 parents. It occurs via the fusion of 2 gametes.
First Meiotic Division
The first division produces two intermediate daughter cells with N chromosomes with sister chromatids.
Chromatin condenses into chromosomes, the spindle apparatus forms, and the nucleoli and nuclear membrane disappear. Homologous chromosomes come together and intertwine in a process called synapsis.
Chromosomes that code for the same traits, one inherited from each parent.
Four chromatids (two sister chromatids) formed in synapsis at prophase I.
When chromatids of homologous chromosomes break at corresponding points and exchange equivalent pieces of DNA.
Occurs between homologous chromosomes and not between sister chromatids of the same chromosomes.
Homologous pairs (tetrads) align at the equatorial plane, and each pair attaches to a separate spindle fiber by its kinetochore.
Each chromosome of paternal origin separates from its homologue of maternal origin, and either chromosome can end up in either daughter cell. Each daughter cell will have a unique pool of genes from a random mixture of maternal and paternal origin.
Occurs in Anaphase I when the homologous pairs separate and are pulled to opposite poles of the cell.
This process accounts for a fundamental Mendelian Law (random daughter cells in respect to parental origin).
A nuclear membrane forms around each new nucleus. At this point, each chromosome still consists of sister chromatids joined at the centromere.
Second Meiotic Division
Very similar to mitosis, except that it is not preceded by chromosomal replication. The chromosomes align at the equator, separate and move to opposite poles, and are surrounded by a re-formed nuclear membrane.
New cells have haploid number of chromosomes.
**In human females, only one of these daughter cells becomes a functional gamete.
Mitosis versus Meiosis
Mitosis 2N --> 2N ... occurs in all dividing cells, homologous chromosomes don't pair up, and no crossing over.
Meiosis 2N --> N ... occurs in sex cells only, homologous chromosomes pair up at metaphase plate, forming tetrads, crossing over can occur.
Sexual Reproduction Definition
Differs from asexual reproduction in that two parents are involved and the end result is a genetically unique offspring. It occurs via the fusion of two gametes- specialized sex cells produced by each parent.
Sexual Reproduction Requirements
Production of functional sex cells (gametes by adult organisms)
Union of these cells to form a zygote
Development of the zygote into another adult, completing the cycle
Gametes produced in specialized organs.
Male gonads produce sperm in the tightly coiled seminiferous tubules.
Female gonads produce oocytes (eggs).
Some species are this. They have both functional male and female gonads.
Example: Include hydra and the earthworm.
Sperm production, which occurs in the seminiferous tubules. Diploid cells are called spermatogonia undergo meiosis to produce four haploid sperm of equal size.
The head consists almost entirely of the nucleus, which contains the paternal genome. The tail (flagellum) propels the sperm, while the mitochondria in the neck and body provide energy for locomotion.
Production of female gametes, occurs in the ovaries One diploid primary female sex cell undergoes meiosis in the ovaries to produce a single mature egg. Each meiotic division produces a polar body. The mature ovum is a large cell containing most of the cytoplasm, RNA, organelles, and nutrients needed by a developing embryo. The polar bodies rapidly degenerate.
Created by each meiotic division. A small cell that contains little more than the nucleus. They rapidly degenerate.
Occurs in vertebrates that reproduce in water. Many eggs must be laid to ensure some fertilization success.
Practiced by terrestrial vertebrates and provides a direct route for sperm to reach the egg cell. Females need to produce fewer eggs.
Regulates secondary male sex characteristics, including facial and pubic hair and voice changes.
Thousands of them make up an ovary. It is a multilayered sac of cells that contain, nourish, and protect an immature ovum. They also produce estrogen.
Steroid hormones produced by ovaries. Necessary for normal female maturation. Stimulate development of the female reproductive tract and contribute to the development of secondary sexual characteristics and sex drive. Also responsible for the thickening of the endometrium (uterine wall).
Secreted by ovarian follicles and corpus luteum.
Steroid hormone secreted by corpus luteum during the luteal phase of the menstrual cycle. Stimulates the development and maintenance of the endometrial walls in preparation for implantation of an embryo.
Begins with the cessation of the menstrual flow from the previous cycle. During this phase, FSH from the anterior pituitary promotes the development of the follicle, which grows and beings secreting estrogen.
Phase were follicles mature.
Follicle stimulating hormone.
Occurs midway through the cycle when a mature ovarian follicle bursts and releases an ovum. It is caused by a surge in LH, which is preceded (in part caused by) a peak in estrogen levels.
Following ovulation, LH induces the ruptured follicle to develop into the corpus luteum.
Secretes estrogen and progesterone. Developes from the ruptrued follicle during the luteal phase.
Happens if the ovum is not fertilized and the corpus luteum atrophies. Progesterone and estrogen levels drop causing the endometrium to fall off and give rise to the menstrual flow.
Human chorionic gonadotrophin. Released if fertilization occurs and it maintains the corpus luteum and therefore the supply of estrogen and progesterone until the placenta can take over the production of these hormones.
Asexual Reproduction Mechanism
Production of offspring without fertilization. Offspring are copies of the parent cell, except for random mutations. 4 different types. Prokaryotes reproduce asexually. All plants do as well.
(Asexual reproduction) Simple form seen in prokaryotes. DNA replicates, and a new plasma membrane and cell wall grow inward along the mid line of the cell, dividing it into two equally sized cells with equal amounts of cytoplasm and each containing a duplicate of the parent chromosome. Examples in one-celled organisms: Amoebae, paramecia, algae, bacteria
(Asexual reproduction) Replication of the nucleus followed by unequal cytokinesis. Creates genetically identical daughter cell that is just smaller. Examples: hydra and yeast
(Asexual reproduction) Regrowth of body part. Replacment of cells occurs by mitosis. Some lower animals (starfish/hydra) have extensive regeneration power.
(Asexual reproduction) Development of an unfertilized egg into an adult organism. Process occurs naturally in some lower organisms (males in bees and ants). Artifical ways can be in frogs or rabbits through electric shock or pinprick.
(Sexual reproduction in plants) Haploid generation produces gametes by mitosis. Union of male and female gametes at fertilzation restores the diploid sporophyte generation.
Diploid generation that reproduces asexually (plants). Evolutionary trend has been towards increased dominance of this generation over the other.
Basic unit of heredity. Composed of DNA and located on chromosomes.
Alternative forms of a gene.
Genetic makeup of an individual.
Physical manifestation of the genetic makeup. Some correspond to a single genotype while others correspond to several different genotypes.
Created Mendelian Genetics in 1860s. Developed basic principles of genetics using the garden pea. Studied inheritance of the individual pea traits by preforming genetic crosses.
Mendel's First Law
Law of Segregation 1. Genes exist in alternative forms (alleles) 2. An organism has 2 alleles for each inherited trait, one from each parent 3. The 2 alleles segregate during meiosis, resulting in gametes that carry only one allele for any given inherited trait. 4. If two alleles in an individual organism are different, only one will be fully expressed and the other will be silent.
The expressed allele, appears in the phenotype.
Organisms that contain two copies of the same allele.
Organisms that carry two different alleles
Illustrates the principles of Mendelian inheritance. Only one trait is studied.
A way of predicting the genotypes expected from a cross.
An organism with a dominant phenotype of unknown genotype (A x) is crossed with a phenotypically recessive organism ( a a). If a recessive phenotype appears in the test cross, the parent was genotypically heterozygous.
Mendel's Second Law
Law of Independent Assortment Genes on the same chromosome will stay together, unless crossing over occurs.
Non-mendelian inheritance pattern. A blend of parental phenotypes. Example: Snapdragon flower color.
Non-mendelian inheritance pattern. Occurs when multiple alleles exist for a given gene and more than one of them is dominant. Each dominant allele is fully dominant when combined with a recessive allele but when two dominant alleles are present, the phenotype is the result of the expression of both dominant alleles simultaneously. Example: Blood types
Most chromosomes in sexually differentiated speices exist as a pair of homologues. Humans have 22
Sex is determined by a pair of these. Females have homologous X chromosomes and males have heterologous X and Y chromosomes.
Determined by the genetic contribution of the male gamete.
50% chance of male or female for each mating!
Genes that are located on the X or the Y chromosome.
In humans, more of these genes are on the X chromosome. Some are on Y, example: hair on the outer ear.
Recessive phenotype are more likely found in males (since nothing to block them). Examples are hemophilia and color-blindness.
Fruit Fly. A very useful study organism in providing explanation to Mendelian Genetic Patterns. Why:
-Short life cycle/reproduces often
-Large sample size/reproduces in large numbers
-Large chromosomes and easily distinguishable
-Chromosomes few (4 pair, 2n=8)
-Mutations occur relatively frequently
Helped elucidate patterns of embryological development.
Environmental Factors on Phenotypes
Can effect the genotype and produce a certain phenotype.
Wings of drosophila, hair color of Himalayan Hare
Either the failure of homologous chromosomes to separate properly during meiosis I or the failure of sister chromatids to separate properly during meiosis II.
Result: Zygote may have 3 copies of that chromosome or a single copy of that chromosome.
Can also occur in sex chromosomes, causing individuals to have extra or missing copies of X and or Y
Somatic cells have 2N + 1 chromosomes.
Example: Down syndrome, caused by chromosome 21.
Most others are lethal, causing the embryo to abort spontaneously early in the pregnancy.
Somatic cells have 2N - 1 chromosomes.
Most are lethal, causing embryo to abort spontaneously early in the pregnancy.
When a chromosome loses a fragment (has a deficiency).
Can occur spontaneously or be induced by environmental factors like mutagenic agents and X-rays!
A change in the genetic information of a cell, coded in the DNA. Moslty occurs in regions of DNA that do not code for proteins and are therefore silent.
In somatic cells, can lead to tumors.
In gametes, it will be transmitted to offspring.
Include: Cosmic rays, X-rays, UV rays, radioactivity, chemical compounds (like colchicine and mustard gas).
Mutagenic agents are generally also carcinogenic.
A nitrogen base can be added, deleted, or substituted thus creating a different gene. Happens because the wrong amino acids are inserted into polypeptide chains and a mutated protein is produced
A molecular disease caused by the inability to produce the proper enzyme for the metabolism of phenylalanine. A degradation product (phenylpyruvic acid) accumulates.
Red blood cells become crescent shaped because they contain defective hemoglobin and therefore can carry less oxygen. It is caused by a substitution of valine (GUA or GUG) for glutamic acid (GAA or GAG), because of a single base pair substitution in the gene coding for hemoglobin.
Deoxyribonucleic acid. What genes are made of. Contained the info coded in the sequence of its base pairs, providing the cell with a blueprint for protein synthesis. Proteins regulate all of life's functions!
DNA can self-regulate (crucial), DNA is the basis of heredity.
The basic unit of DNA, composed of deoxyribose ( a sugar) bonded to both a phosphate group and a nitrogenous base (there are 2 different types of bases)
A type of nitrogenous base.
Adenine (A) and Guanine (G)
A type of nitrogenous base.
Cytosine, Uracil in RNA, Thymine
CUT the Pie (Pye)
Shape of DNA molecule. Has sugar-phosphate chains on the outside of the helix and the bases on the inside. T and A always form 2 hydrogen bonds and G and C always form 3 hydrogen bonds. This forms "rungs"
Also known as Watson-Crick DNA Model.
Double-stranded DNA Molecule undwinds and separates into two single strands. Each strand acts as a template for complemeary base-pairing in the synthesis of two new daughter helices. Each new daughter helix is an intact stran from the parent and a newly synthesized strand
DNA Replication is this because the daughter the strand contains one intact strand from the parent helix and one newly synthesized helix strand.
Series of triplets, which is how the base sequence of mRNA is translated. The three consecutive vases code of a particular amino acid. The genetic code is universal for all organisms.
64 codons are possible but only 20 amino acids need to be coded for.
Also known as redundancy.
Property of amino acids having more than one codon specifying them.
(pg. 56 in the book)
Structure of RNA
Ribonucleic acid is a polynucleotide structurally similar to DNA except that its sugar is ribsoe, it contains uracil instead of thymine and is usually single stranded. Can be found in both nucleus and cytoplasm.
mRNA, tRNA, rRNA
The inverted complement of a DNA sequence and transports it from the nucleus to the ribosomes, where the protein synthesis occurs.
Assembled from ribonucleotides.
Small RNA found in the cytoplasm that aids in the translation of mRNA's nucleotide code into a sequence of amino acids. Brings amino acids to the ribosomes during protein synthesis. At least one type for each amino acid, about 40 known in all.
A structural component of ribosome, it is the most abundant of all RNA types. It is synthesized in the nucleolus.
Process whereby information coded in the base sequence of DNA is transcribed into a strand of mRNA which leaves the nucleus through nuclear pores. The remaining events of protein synthesis occur in the cytoplasm.
Process whereby mRNA codons are translated into a sequence of amino acids. Occurs in the cytoplasm and involves tRNA, ribosomes, mRNA, amino acids enzymes, and other proteins.
tRNA in Translation
Brings amino acids to the ribosomes in correct sequence for polypeptide synthesis. tRNA can recognize both the amino acid and the mRNA codon. This dual function is reflected in its three-dimensional structure.
A three-nucleotide sequence in the end of tRNA that is complementary to one of the mRNA codons.
Each amino acid has their own. It has an active site that binds to both the amino acid and its corresponding tRNA, catalyzing their attachment to form an aminoacyl-tRNA complex.
Ribosomes in Translation
Composed of two subunits (consisting of proteins and rRNA), one large and one small, that bind together only during protein synthesis. Have three binding sites, one for mRNA and two for tRNA (P and A site)
A ribosome subunit. Peptidyl-tRNA binding site, Binds to the tRNA attached to the growing polypeptide chaine.
A ribosome subunit. Aminoacyl-tRNA complex binding site. Binds to the incoming aminoacyl-tRNA complex.
3 stages: Initiation, elongation, termination
When polypeptide synthesis starts the ribosome binds to the mRNA near its 5' end. The ribosome scans the mRNA until it binds to a start codon (AUG).
Hydrogen bonds form between the mRNA codon in the A site and its complementary anticodon on the incoming aminoacyl-tRNA. A peptide bond is formed between the amino acid attached to the tRNA in the A site and met attached to the tRNA in the P site.
Completes polypeptide syntehse. Ribosome advances three nucleotides along the mRNA in the 5' to 3' direction. In a concurrent action, the uncharged tRNA from the P site is expelled and the peptidul-tRNA from the A site moves to the P Site. Ribdome then has an empty A site ready for the entry of the aminoacyl-tRNA corresponding to the next codon.
Polypeptide synthesis ends when one of 3 special mRNA termination codons (UAA, UAG, UGA) arrives in the A site. These codons signal the ribosome to terminate translation, they don't code for amino acids. P
Structure formed by many ribosomes simultaneously translating a single mRNA molecule.
Conformation is determined by this.
Heredity systems that exist outside of the nucleus. Cytoplasmic genes may interact with nuclear genes and are inportant in determing the characteristics of their organells (like chloroplasts, mitochondria).
Drug resistance in many microorganisms is regulated by these, which are cytoplasmic rings of DNA and they contain one or more genes.
Consists of a single circular chromosome located in the nucleoid region of the cell. Many contain plasmids as well which have accessory genes.
Plasmids that are cpable of intergration into the bacterial genome.
Replication in Bacteria
Begins at a unique origin of replication and proceeds in both directions simultaneously. DNA synthesized in the 5' to 3' direction.
Genetic Variance in Bacteria
Reproduce by binary fissionbut can still have genetic variance in a population through 3 mechanisms: transformation, conjugation, and transduction. All three increase genetic variance.
Process by which a foreign chromosome fragment (a plasmid) is incorporated into the bacterial chromosome via recombination, creating new, inheritable genetic combinations.
Sexual mating in bacteria. Transfer of genetic material between two bacteria that temporarily joined. A temp. cytoplasmic conjugation bridge is formed btwn the 2 cells and genetic material is transferred from donor male (+) to recipient female (-).
In E. coli. Those with the plasmid are F+ cells (without F-). During conjugation, the F+ replicates its f factor and transfers it to the F- cell, making it an F+ cell. Other genes (such as antibody resistance) may be found on the plasmids and transferred as well.
High frequency of recombination cells. When the sex factor becomes integrated into the bacterial genome. The conjugation bridge usually breaks down before the entire chromosome is transferred but the genes that do get in can easily recombine with the already present bacterial genes. Forms novel genetic combinations.
Occurs when fragments of the bacterial chromosome accidentally become packaged into viral progeny produced by viral infection. A virion can infect other bacteria and introduce new genetic arrangements through recombination with the new host cell's DNA. The closer two genes are to one another on a chromosome the more likely they will be to transduce together. This fact allows geneticists to map genes to a high degree of precision.
Occurs when linked genes are separated. It occurs by breakage and rearrangements of adjacent regions of DNA when organisms carrying different genes or alleles for the same traits are crossed.
Enables prokaryotes to control their metabolism. It is based on the accessibility of RNA polymerase to the genes being transcribed and is directed by an operon.
Directs gene regulation. Consists off structural genes, an operator gene, and a promoter gene.
Part of the operon, which regulates transcription.
Contains sequences of DNA that code for proteins.
Part of the operon which regulates transcription.
It is a sequence of non-transcribable DNA that is the repressor binding site.
Part of the operon which regulates transcription.
It is the noncoding sequence of DNA that serves as the initial binding site for RNA polymerase.
Codes for the synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase from transcribing the structural genes.
Synopsis of Gene Regulations
RNA polymerase binds to promoter --> structural genes transcribed
Repressor binds to operator --> structural genes NOT transcribed (regulator codes for repressor)
Induced binds to repressor --> no binding to operator --> structural genes transcribed
Repressor binds to the operator in this system, forming a barrier that prevents RNA polymerase from transcribing structural genes. For transcription to occur, an inducer must bind to the repressor, forming an inducer-repressor complex. This blocks it from binding to the operator, thus allowing transcription to occur! Enzymes are only transcribed when they are needed becasue the substrate is the inducer.
The repressor is inactive until it combines with the corepressor, which is usually an end product of a biosynthetic pathway that they control. The proteins produced are repressible since they are normally being synthesized.
An operon that contains mutations such as deletions or whose regulator genes codes for defective repressors are incapable of being turned off in a repressible system. So these enzymes are always being synthesized.
A virus that infects its host bacterium by attaching to it, boring a hole through the bacterial cell wall and injecting its DNA while its protein coat remains attached to the cell wall. Once inside its host, the bacteriophage enters either a lytic cycle or a lysogenic cycle.
Phage DNA takes control of the bacterium's genetic machinery and manufactures numerous progeny. Cell then burst, releasing new virions, each caapable of infecting other bacteria. Bacteriophages that replicate by the lyric cycle are called virulent.
If a bacteriophage does not lyse the cell, it becomes integrated into the bacterial genome in a harmless form, lying dormate for one or more generations. Spontaneously or from environmental factors, the prophage can re-emerge and enter the lytic cycle.
Harmless form of the bacteriophage that is integrated into the bacterial genome. Bacteria containing these are resistant to further infection ("superinfection") by similar other phages.
Allow for the detection of a specific DNA sequence in a specific DNA sample. In this process, DNA is cleaved into restriction fragments by restriction endonucleases that cut at specific restriction sites. The fragments are separated by gel electrophoresis. The desired sequence is detected by washing a radioactively labeled probe over a paper containing the gel's pattern.
Joins DNA fragments by catalyzing the formation of phosphodiester bonds between DNA nucleotides.
Polymerase chain reaction (PCR)
Used for amplification of genes. Composed of 3 steps: denaturation, primer annealing, primer extension.
Step One of PCR DNA is denatured with heat to separate the strands. A single strand acts at the template DNA and it holds the specific sequence that needs to be amplified.
Step Two of PCR Complementary nucleotides called primers join the single-stranded templates.
Step Three of PCR DNA polymerase joins deoxynucleotide triphosphates (dNTP) to the primers, leading to the addition of nucleotides complementary to the template.
Cloning DNA in Bacteria
Another way to amplify genes. Involves the ligation of the DNA sequence of interest with vector DNA fragments. Vector gragments are most often self-replicating phages or plasmids. Once the recombinant model is made, it can be inserted into a bacteria strain, through transformation will produce identical copies of the DNA!!!
The study of the decelopment of a unicellular zygote into a complete multicellular organism.
Early decelopmental stage Egg can be fertilized within 12-24 hrs following ovulation. Fertilization occurs in the lateral, widest portion of the oviduct when sperm traveling from the vagina encounters an egg. If more than one egg is fert. then fraternal twins may be conceived.
Rapid mitotic divisions occuring in early embryonic development. Lead to an increase in cell number without a corresponding growth in cell protoplasm. Cleave increases ratio of nuclear to cytoplasmic material as well as surface-to-volume ratio, which improves gas and nutrient exchange.
Results in cells that maintain the ability to develop into a complete organism. Identical twins are result of this.
Results in cells whose future differentiation pathways are determined at an early developmental stage. Differentiation is the specialization of cells that occurs during development.
First complete cleavage = 32 hours after fertilization Second = 60 hours Third = 72 hours, at which the 8-celled embryo reaches the uterus.
A solid ball of embryonic cells that is formed as cell division continues.
Begins when the morula develops a fluid-filled cavity called the blastocoel, which by the fourth day has become a hollow sphere of cells known as the blastula.
Process of transforming the single-cell layer of the blastula into a three-layered structure. These three primary germ layers are responsible for the differential development of the tissues, organs, and systems of the body at later stages of growth
Integument (includes epidermis, hair, nails, epithelium of nose, mouth, and anal canal Lens of eye, retina, nervous system
Epithelial linings of digestive and respiratory tracts (incl. die lungs), parts of liver, pancreas, thyroid, and bladder lining
Musculoskeletal system, circulatory system, excretory system, gonads, connective tissue throughout body and portions of digestive and repiratory organs
Fish and amphibians lay eggs that are fertilized externally in thewater. Embryo develops within the egg, feeding on nutrients stored in the yolk. Reptiles, birds, some mammals develop externally on land. Fert. occurs internally and the fertilized egg is then laid. Eggs provide protection for developing embryo.
Embryonic membrane of egg. Lines the inside of the shell. It is a moist membrane that permits gas exhange.
Embryonic membrane of egg. Saclike structure is involved in respiration and excretion and contains numberous blood vessels to transport O2, CO2, water, salt, and nitrogenous wastes.
Embryonic membrane of egg. Membrane encolses amniotic fluid. Amniotic fluid provides an aqueous environment that protects the developing embryo from shock.
Embryonic membrane of egg. Encloses the yolk. Blood vessels in the yolk sac transfer food to the developing embryo.
Nonplacental Internal Development
Early devo within the body of the mother protects the young. Marsupials and some tropical fish: Develop in mother without placenta. Exchange of food and oxygen between the younf and the mother is limited The young may be born very young.
Placental Internal Development
Growing fetus receives oxygen directly from its mother through a specialized circulatory system. System not only gives O2 and nutrients to the fetus but removes CO2 and metabolic wastes as well. The two components of this system are the placenta and umbilical cord.
Develops in the first few weeks following fertilization. Outgrowth of the 4 extraembryonic membranes formed during devo: amnion, chorion, allantois and yolk sac. the formation begins with the chorion, a membrane that completely surrounds the amnion.
Vessels are formed from the enlarged blood vessels of the allantoic wall and they conect the fetus to the developing placenta.
A series of strong uterine contractions that accomplishes childbirth. 3 stages.
First Stage of Labor
Cervix thins and dilates and the amniotic sac ruptures, releasing its fluids. Contractions are relatively mild during this time.
Second Stage of Labor
Rapid contractions, resulting in the birth of the baby followed by the cutting of the umbilical cord.
Third Stage of Labor
Uterus contracts, expelling the placenta and umbilical cord.
Circulation in Protozoans
(invertebrates) Movement of gaes and nutrients is accomplished by simple diffusion with the cells.
Circulation in Cnidarians
(Invertebrates) Hydra and other types have body walls that are two cells thick. All cells are in direct contact with either the internal or external environments, so there is no need for a specialized circulatory system.
Circulation in Arthropods
Have open circulatory systems in which blood is in direct contact with the body tissues. The blood is criculated primarily by body movements. Blood blows through a dorsal vessel and into space called sinuses, where exchange occurs.
Circulation in Annelids
Uses a closed circulatory system to deliver materials to cells taht are not in direct contact with the external environment. In this system, blood is confined to blood vessels. It moves towards the head in the dorsal vessel, which functions as the main heart by coordinated contractions. Five pairs of vessels called aortic loops connect the dorsal vessel to the ventral vessel nd function as additional pumps. Earthworms lack red blood but have a hemoglobin-like pigment dissolved in aqueous sol
Circulation Overview in Humans
Composed of 4 chambered heart, network of blood vessels and blood itself. Oxygenated blood is pumped from the left ventricle to the aorta, which branches into a series of arteries. The arteries branch into arterioles and then into microscopic capillaries.
Right side pumps deoxgenated blood into pulmonary circulation (towards lungs) while left side pumps oxygenated blood into systemic circulation (throughout the body). Upper chambers are thin walled atria and bottom are muscular ventricles.
Thick-walled, muscular, elastic vessels that transport oxygenated blood away from the heart- except for pulmonary which transport deoxygenated blood from the heart to the lungs.
Relatively thinly walled, inelastic vessels that conduct deoxgenated blood towards the heart- expect for pulmonary which carry oxygenated blood from the lungs to the heart.
Smallest diameter of all three types of vessels, red blood cells must often travel through them in a single file!
Transports excess interstitial fluid called lymph, to the cardiovascular system, thereby keeping fluid levels in the body constant. The nodes are swellings that contain phagocytic cells that filter and remove/destroy any foreign particles and pathogens!
Humans have on average 4 to 6 liters. 55% liquid and 45% cellular components. Plasma is the liquid portion of the blood. It is an aqueous mixture of nutrients, salts, respiratory gases, wastes, hormones, and blood proteins. Cellular components are erthrocytes, leukocytes, and platelets.
Red Blood Cells
Oxygen-carrying components. Contains approx. 250 million molecules of hemoglobin (each bind 4 o2). When its bound, its oxyhemoglobin. Formed from stem cells in bone marrow. They circulate for about 120 days then they are phagocytized by special cells in the spleen and liver.
White Blood Cells
Larger than erthrocytes and serve protective functions. Some phagocytize foreign matter and organisms such as bacteria. Others migrate from the blood to tissue, where they mature into stationary cells called macrophages. Some become lymphocytes and are involved in immune response and the production of antibodies (B cells) or cytolysis of infected cells (T cells)
Cell fragments that lack nuclei and are involved in clot formation.
Transport of Gases
A function of the circulatory system. Erythrocytes transport O2 throughout the circulatory system. Actually, it is the hemoglobin molecules in erythrocytes that bind to O2. Each hemoglobin molecule is capable of binding to four molecules of 02. Hemoglobin also binds to CO2
Transportation of Nutrients and Wastes
A function of the circulatory system. Amino acids and simple sugars are absorbed into the bloodstream at intestinal capillaries. After processing, they are transported throughout the body, where metabolic waste products diffuse into capillaries from surrounding cells. These wastes are then delivered to the appropriate excretory organ.
Function of the circulatory system. Occurs when platlets come into contact with exposed collagen of damaged vessel and release a chemical that causes neighboring platelets to adhere to one another, forming a platelet plug. Then platelts and damaged tissue releases thromboplastin.
A clotting factor released by platelets and damaged tissue. With the aid of its cofactors (Calcium, vit K), it converts the inactive plasma protein prothrombin to its active form, thrombin. Thrombin then converts fibrinogen into fibrin. Threads of fibrin coat the damaged area and trap blood cells to form a clot. Clots prevent extensive blood loss while the damaged vessel heals itself. Fluid left after blood clotting is called serum.
Involves the production of antibodies. Is responsible for the proliferation of antibodies following exposure to antigens.
Part of humoral immunity. Their response is very specific to the antigen (nonself entities) involved. Also called immunoglobulins (lgs) are complex proteins that recognize and bind to specific antigens and trigger the immune system to remove them. Either attract other cells like leujocytes to phagocytize the antigen or cause the antigens to clump (agglutinate) and form large, insoluble complexes, facilitating their removal by phagocyric cells.
Type of humoral Immunity Referes to production of antibodies during an immune response. Can be conferred by vaccination
Type of active immunity An indvidual is injected with a weakened, inactive, or related form of a particular antigen, which stimulates the immune systems to produce specific antribodies against it. May require weeks to build up. P
Type of humoral immunity Involves the transfer of antibodies produced by another individual or organism. Aquired either passively or by injection. Example: antibodies crossing the placenta and entering fetal circulation. Is acquired immediately but is very short-lived, lasting only as long as the antibodies circulate in the blood system. Usually not very specific.
Fraction of the blood containing a wide variety of antibodies can be used to confer temporary protection against hepatis and other diseases by passive immunity (type of humoral immunity).
Nonspecific Defense Mechanism: Skin
Physical barrier against bacterial invasion. Also, pores on the skin's surgace secrete sweat, which contains an enzyme that attacks bacterial cell walls.
Initiated by the body in response to phyisical dmage. Injured cells release histamine, which causes blood vessels to dilate, thereby increasing blood flow to the damaged region. Granulocytes attacted to the injury site phagocytize antigenic material. This response is often accompanied by a fever.
Nonspecific Defense Mechanisms: Interferons
Proeins that are produced by cells under viral attack. These proteins diffuse to other cells, where they help prevent the spread of the virus.
Inappropriate responses to certain foods and pollen can cause the body to form antibodies and release histamine.
Rejection of Transplants
Occurs when the tissue or organ is detected as being foreign by the recipient's immune system. The resulting response can cause the tissue or organ to be rejected. Immuno-suppressing drugs can be used to lower the immune response to transplants and decrease the likelihood of rejection.
ABO Blood Types
Erythrocytes have characteristic cell-surgace proteins, antigens, which are macromolecules that are forgein to the host organism and trigger an immune response. 2 major groups of red blood cell antigens are the aBO group and the Rh factor.
Type AB Blood
Universal recipient because it has neither anti-A or anti-B antibodies. T
Type O Blood
Universal donor because it will not elicit a response from the recipient's immune system since it does not possess any surface antigens.
An antigen that may be present on the surface of red blood cells. Important during pregnancy. When anti-Rh antibodies cross the placenta to a Rh+ fetus, they destroy fetal red blood cells leading to severe anemia known as erythroblastosis fetalis.
Endocrine System Definition
A means of internal communication, coordinationg the activities of the organ system. The glands of this system synthesize and secrete chemical substances called hormones directly into the circulatory system.
Situated on top of the kidneys and consist of the adrenal cortext and the adrenal medulla.
Part of the Adrenal glands. ACTH in response to stree stimulates the adrenal cortex to synthesize and secrete the steroid hormones, which are collectively known as corticosteroids. They are derived from cholesterol and include glucocorticoids, mineralocorticoids and cortical sex hormones.
Include cortisol and cortisone Involved in glucose regulation and protein metabolism. Raise glucose levels by promoting protein breakdown and gluconeogenesis and decreasing protein synthesis. They raise the plasma glucose levels and are antagonistic to the effects of insulin.
These (particularyly aldosterone) regulate plasma levels of sodium and potassium and, consequently, the total extracellular water volume.
A mineralocorticoid. Causes active reabsorption of soidum and passive reabsorption of water in the nephron. This results in a rise in both blood volume and blood pressure. Excess production of aldosterone results in excess retention of water with resulting hypertension (high blood pressure).
Cortical sex hormones
Secreted in small quantities from adrenal cortext, androgens (male sex hormones) in both men and women. In males most produced by testes and effect is quiet small. In females, overproduction of these can have masculinizing effects like excessive facial hair.
Produces epinephrine (adrenaline) and norepinephrine (noradrenaline) both belong to a class of amino acid-derived compounds called catecholamines
Produced by adrenal medulla. Increases the conversion of glycogen to glucose in liver muscle tissue, causing a rise in blood glucose levels and an increase in the basal metabolic rate. Can inhibit digestion and other "vegatative" functions that are not immediately important for survial.
Include epinephrine and norepinephrine which increase the rate and strength of the heartbeat and they dilate and constrict blood vessels in such a way as to increase the blood supply to skeletal muscle, the heart, and the brain while decreasing the blood supply to the kidneys, skin, and digestive tract. Fight or flight.
Control of Adrenal Hormones
Under the control of ACTH (adrenocorticotrophic hormone) which is secreted by the anterior pituitary gland. Stimulates the production of glucocorticoids and sex steroids, aldosterone production is controled by a different mechanism.`
Small, trilobed gland lying at the base of the brain. The two main lobes, anterior and posterior, are functionally distinct.
Synthesizes both direct hormones, which directly stimulate their target organs, and tropic hormones, which stimulate other endocrine glands to release hormones. The hormonal secretions are regulated by hypothalamic secretions called releasing/inhibiting hormones or factors.
A direct hormone, GH, somatotropin Promotes bone and muscle growth. In children, a deficiency can lead to stunted growht (dwarfism) while too much results in gigantism. In adults, too much causes acromegaly, a disorder characterized by a disproportionate overgrowth of bone, localized especially in the skull, jaw, feet, and hands
A direct hormone Prolactin stimulates milk production and secretion in female mamary glands.
Tropic Hormone Stimulates the adrenal cortex to synthesize and secrete glucocoticoids and is regulated by the releasing hormone corticotrophin-releasing factor (CRF)
Thyroid-stimulating hormone TSH
A tropic hormone Stimulates the thyroid gland to synthesize and release thyroid hormones, including thyroxin
Luteinizing Hormone LH
Tropic hormone In females, this stimulates ovulation and formation of the corpus luteum. In males, it stimulates the interstitial cells of the tests to synthesize testosterone
Follicle-stimulating Hormone FSH
In females, it causes maturation of ovarian follicles which behin secreting estrogen. In males it stimulates maturation of the seminiferous tubules and sperm repoduction.
Secreted by the intermediate lobe of the pituitary. In mammals, the function is unclear but in frogs, it causes the darkening of the skni via induced dispersion of molecules of pigment in melanophore cells.
(Neurohypophysis) Does not synthesize hormones. It stores and releases the peptide hormones oxytocin and ADH which are produced by the neurosecretory cells of the hypothalamus. Hormone secretion is stimulated by action potentials descending from the hypothalamus.
Peptide hormone Secreted during childbirth, increases the strength and frequency of uterine muscle contractions. Its secretion is also induced by suckling; it stimulates milk secretion in the mammary glands.
Antidiuretic hormone (ADH, vasopressin)
Peptide hormone Increases the permeability of the nephron's collecting duct to water, thereby promoting water reabsorption and increasing blood volume. It is secreted when plasma osmolarity increases, as sensed by osmoreceptors in the hypothalamus, or when blood volume decreases, as sense by baroreceptors in the circulatory system.
Part of the forebrain and is located directly above the pituitary gland. Recieves neural transmissions from other parts of the brain and from peripheral nerves which trigger specific responses from its neurosecretory cells. Neurosecretory cells regulate pituitary gland secretions via negative feedback mechanisms an through the actions of inhibiting and releasing hormones!!!
Hypothalamus Interactions with Anterior Pituitary
Hypothalamic-releasing hormones stimulate or inhibit the secretions of the anterior pituitary. Example: GnRH stimulates the anterior pituitary to secrete FSH and LH. Releasing hormones are secreted in the hypothalamic-hypophyseal portal system. Allows releasing hormones to immediately reach the anterior pituitary.
Feedback system regulating secretions of the endocrine system
"Complicated". Example: When plasma levels of adrenal cortical hormones drop, hypothalamic cells (via a negative feedback mechanism) release ACTH-releasing factor into the portal system. When plasma concentration of corticosteroids exceeds the normal plasma level, the steroids themselves exert an inhibitory effect on the hypothalamusI
Hypothalamus interactions with posterior pituitary
Neurosecretory cells in the hypothalmus synthesize noth oxytocin and ADH and transport them via their axons into the posterior pituitary for storage and secretion.
Is a bilobed structure located on the ventral surface of the trachea. It produces and secretes thyroxin and triiodothyronine (the thyroid hormones) and calcitonin.
Thyroid Hormones (Thyroxine (T4) and Triiodothyronine(T3))
Dervived from the iodination of the amino acid tyrosine. They are necessary for growth and neurological development in children. They increase the rate of metabolism throughout the body. `
Thyroid hormones are undersecreted or not secreted at all. Symptoms include slowed heart rate and respiratory rate, fatigue, cold intolerance, and weight gain. Called cretinism in newborn infants and is characterized by mental retardation and short stature. Thyroid often enlardes, forming a bulge in the neck termed a goiter.
Overstimulated thyroid, resulting in the oversecretion of thyroid hormones. Symptons include increased metaboilc rate, feelings of excessive warmth, profuse sweating, palpitations, weight loss, and protruding eyes. Thyroid often enlardes, forming a bulge in the neck termed a goiter.
Decreases plasma Ca2+ concentration by inhibiting the release of Ca2+ from bone. Secretion is regulated by plasma Ca2+ levels. Is antagonistic to parathyroid hormone.
Both an exocrine and endocrine organ. Exicrine function is performed by cells that secrete digestive enzymes into the small intestine via a series of ducts. Endocrine function is performed by small glandular structures called the islets of Langerhans which have alpha cells producing and secreting glucagon and beta cells producing and secreting insulin.
Stimulates protein and fat degradation, the conversion of glycogen to glucose, and gluconeogensis, all which serve to increase bllod blucose levels. Is largely antagonistic to thsoe of insulin.
Protein hormone secreted in response to high blood clucose concentration. Stimulates the uptake of glucose by muscle and adipose cells and the storage of glucose as glycogen in muscle and liver cells, thus lowering blood glucose levels. Also stimulates the synthesis of fats from glucose and the uptake of amino acids. Actions are antagonistic to those glucagon and glucocorticoids.
Underproduction of insulin or insensitivity to insulin. Characterized by hyperglycemia, high blood glucose levels.
Synopsis of Plasma Glucose
Insulin DECREASES plasma glucose
Glucagon INCREASES plasma glucose
Dont forget that growth hormone, the glucocoticoids, and epinephrine are also capable of increasing plasma glucose.
Four small, pea-shaped structures embedded in the posterior surface of the thyroid. Synthesize and secrete parathyroid hormone (PTH), which regulates plasma Ca2+ concentration.
Regulates plasma Ca2+ concentration. It increases Ca2+ concentration in the blood by increasing bone resportion and decreasing Ca2+ excretion in the kidneys. Calcium in bone is bonded to phosphate and breakdown of the bone releases phosphate as well as calcium. PTH compensates for this by stimulating excretion of phosphate by the kidneys.
Produced by the kidneys when blood level falls. This enzyme converts plasma protein angiotensinogen to angiotensin I. Which is then converted to angiotensin II which then stimulates the adrenal cortex to secrete aldosterone.
Helps to restore blood volume by increasing sodium reabsorption at the kidney, leading to an increase in water. Removes the initial stimulus for renin production.
Released when food is ingested. It is carried to the gastric glands and stimulates the glands to secrete HCl in response to food in the stomach. Secretion of pancreatic juice, the exocrine secretion of the pancreas, is also under hormone control.
Released by the small intestine when acidic food material enters from the stomach. Stimulates the secretion of an alkaline bicarbonate solution from the pancreas , which neutralizes the acidity of the chyme (partially digested food ew).
Released from the small intestine in response to the presence of fats and causes the contraction of the gallbladder and release of bile into the small intestine.
Involved in digestion of fats!`
Tiny structure at the base of the brain that secretes the hormone melatonin.
Secreted by pineal gland. Role in humans is a little unclear but it is thought that it plays a role in regulating circadian rhythms. Regulated by light and dark cycles in the environment. In primitive vertebrates, it lightens the skin by concentrating pigment granules in melanophores (antagonist to MSH)
Range from simple, short amino acid chains (ADH) to complex polypeptides (insulin). First act as messengers. Bind to specific receptors on the surface on their target cells triggering a series of enzymatic reactions within each cell, the first which may be the conversion of ATP to cyclic adenosine monophosphate (cAMP). reaction is catalyzed by the membrane-bound enzyme adenylate cyclase.
(Part of peptide hormones)
Acts as a second messenger, relating messages from the extracellular peptide hormone to cytoplasmic enzymes an initiating a series of successive reactions in the cell. This is an example of cascade effect. Activity is inactivated by the cytoplasmic enzyme phosphodiesterase.
With each step, the hormone's effects are amplified. Cyclic AMP is an example.
Hormones (like estrogen and aldosterone) belong to a class of lipid-derived molecules with a characteristic ring structure. Produced by testes, ovaries, placenta, and adrenal cortex. Lipid soluble so enter their target cells directly and bind to specific receptor proteins in the cytoplasm. Receptor-hormone complex enters the nucleus ad directly actives the expression of specific genes by binding to receptors on the chromatin. This induces a change in mRNA transcription and protein synthesis.
Synopsis of Mechanism of hormone action
Peptide hormones: Surface receptors and generally act via secondary messengers
Steroid hormones: Intracellular receptors and hormone/receptor binding to DNA promotes transcription of specific genes.
Nervous System Definition
Enables organisms to receive and respond to stimuli from their external and internal environments. Responds to stimuli more rapidly than the endocrine system.
Functional unit of the nervous system. Converts stimuli into electrochemical signals, which are conducted through the nervous system.
An elongated cell consisting of several dendrites, a cell body and a single axon.
Cytoplasmic extensions that receive information and transmit it towards the cell body.
Cell body (soma)
Contains the nucleus and controls the metabolic activity of the neuron.
Long cellular process that transmits impulses away from the cell body. Most mammalian axons are sheathed by an insulating substance known as myelin, which allows axons to conduct impulses faster.
Those traveling from the spine to the tip of the foot may be very long.
Allows axons to conduct impulses faster. Produced by cells known as glial cells. (Oligodendrocytes produce myelin in the central nervous system and Schwann cells produce myelin in the peripheral nervous systems)
Nodes of Ranvier
The gaps between segments of myelin.
Swellings that are the end of axons (sometimes called synaptic boutons or knobs).
Released from synaptic terminals into the synapse (or synaptic cleft) which is the gap between the axon terminals of one cell and the dendrites of the next cell.
Impulses that travel the length of the axon and invade the nerve terminal, thereby causing the release of neurotransmitter into the synapse.
Potential difference when a neuron is at rest between the extracellular space and the interacellular space. At rest, the neuron is still polarized because of an unequal distribution of ions between the inside and outside of the cells. Typical resting membrane potential is -70 millivolts, so inside of the neuron is more negative than the outside. Maintained by active transport of the Na+/K+ ATPase.
Concentration of K+ is higher inside the neuron than outside, the concentration of Na+ is higher outside. Negatively charged proteins are trapped inside of the cell. Rest potential is created b/c the neuron is selectively permeable to K+ so K+ diffuses down its concentration gradient, leaving a net negative charge inside.Neurons are impermeable to Na+ so the cell remains polarized. Bcof the transmission of action potentials, gradients must be restored by the pump. 3 NA+ out for every 2 K+ in
Occurs when the cell becomes sufficiently excited or depolarized. Min. threshold membrane potential (usually around -50mV) is the level at which it is generated.
Voltage-gated Na+ Channels
Located in the nerve cell membrane and open in response to depolarization, allowing Na+ to rush down its electrochemical gradient into the cell, causing arapid further deporlarization. Then they close.
Voltage-gated K+ Channels
Open after Na+ gated channels. They allow K+ to rush out down its electrochemical gradient. This returns the cell to a more negative potential, a process known as repolarization. The neuron may shoot past the resting potential and become even more negative inside than normal (hyperpolarization).
The period of time after an action potential where it is difficult or impossible to initiate another one.
Whenever the threshold membrane potential is reached, an action potential with a consistent size and duration is produced. The nerve fires either maximally or not at all. Stimulus intensity is coded by the frequency of action potentials.
Information travels from dendrite to synaptic terminal. Different axons can send action potentials at different speeds. The greater the diameter of the axon and the more heavily it is myelinated, the faster the impulses will travel. Myelin increases conduction velocity by insulating segments of the axon, so the membrane is permeable to ions only in the nodes of Ranvier, so AP "jumps" from node to node.
Gap between the axon terminal of one neuron and the dendrites of another.
Chimcal messengers in membrane-bound vesicles in the nerve terminal. Released into synapse when AP arrives at the nerve terminal and depolarizes it and the synaptic vesivles fuse with the presynaptic membrane.
Effect of Drugs: Curare
Blocks the postsynaptic acetylcholine receptors so that acetylcholine is unable to interact with the receptor. This leads to paralysis by blocking nerve impulses to muscles.
Effects of Drugs: Botulism Toxin
Prevents release of acetylcholine from the presynaptic membrane and results in paralysis.
Effects of Drugs: Anticholinesterases
Ussed as nerve gases and in the insecticide parathion. Substances inhibit the activity of acetylcholinterase enzyme. As result, acetylcholine is not degraded in the synapse and continues to affect the postsynaptic membrane. Therefore, no coordinated muscular contractions can take place.
Neurons that carry sensory information about the external or internal environment to the brain or the spinal cord.
Neurons that carry motor commands from the brain or the spinal cord to various parts of the body (like muscles or glands).
Neurons that participate only in local circuits, linking sneory and motor neurons in the briain and spinal cord. Their cell bodies and their nerve terminals are in the same location!
A network of nerve fibers (a nerve is essentially bundels of axons)
A cluster of neuronal cell bodies in the periphery.
A cluster of neronal cell bodies in the central nervous system.
Central Nervous System Components
Brain, Spinal cord
Peripheral Nervous System Components
Somatic and Autonomic (consisting of sympathetic and parasympathetic)
Central nervous system. It is a mass of neurons in the skill. Functions include interpreting sensory info, forming motor plans, and cognitive function. Consists of gray matter (cell bodies) on the outside and white matter (myelinated axons) on the inside. Can be divided into forebrain, midbrain, hindbrain.
Forebrain Consists of telencephalon and diencephalon.
Part of the forebrain. Major component of it is the cerbral cortext. Also has olfactory bulb
Major component of the telencephalon. Highly convoluted gray matter thacan be seen on the surgace of the brain. It processes and integrates sensory input and motor responses and is important in memory and creative thought.
Center for reception and integration of olfactory input.
Part of the forebrain. Contains the thalmus and the hypothalmus.
Part of the diencephalon. Relay and intergration center for the spinal cord and cerebral cortex.
Part of the diencephalon Controls visceral functions, like hunger, thirst, sex drive, water balance, blood pressure, and temperature regulation. Also plays important role in the control of the endocrine system.
Midbrain Relay center for visual and auditory impulses. Plays an important role also in motor control.
Hindbrain. Consists of cerebellum, the pons, and the medulla
Part of the hindbrain. Helps to modulate motor impulses initiated by the cerbral cortex and is important in the maintenance of balance, hand-eye coordination, and the timing of rapid movements.
Part of the hindbrain. One function is to oact as a relay center to allow the cortex to communicate with the cerebellum.
Part of the hindbrain.
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