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How is bacterial cell division different from eukaryotic cell division in terms of number of: (1) chromosomes involved
(2) use of mitotic spindle fibers
(3) coiling and uncoiling of chromosomes during division
(4) amount of DNA that can be handled by cell division
(1) number of chromosomes invloved
(2) use of mitotic spindle fibers
(3)coiling and uncoiling of chromosomes
(4)amount of DNA that can be handled by cell division
chromatin: DNA protein material. consists of DNA complexed with histones and other proteins.
-two sister chromatids form
-condense and attach at kineticore
- separated into two separate cells
What event(s) characterizes each of the following cell stages:
G0: effectively exited the cell cycle. post-mitotic.
G1: constitutes the first part of interphase before DNA synthesis
S: synthesis of DNA. replication of genetic material.
G2: between the synthesis of DNA and mitosis
M: mitotic phase. actual division of the cell
chromosomes condense into compact structures
formation os the spindle apparatus (structure that produces mechanical forces that pull chromosomes to poles and push poles away from each other)
The homolog pairs come together in a pairing process called synapsis. The structure that results from synapsis is called a tetrad, consisting of two homologs. The chromatids of the homologs are called non-sister chromatids.
nucleolous disappears and nuclear envelope disintegrates
kinetechose microtubules from each spindle attach to one of the two sister chromatids of each chromosome. begin moving to middle
centrosomes continue movement to opposite poles
centrosomes complete migration to opposite poles (formation of spindle apparatus complete)
at end of phase, chromosomes are lined up along the metaphase plate
centromeres holding sister chromatids together split, they are pulled apart
kinetochore microtubules shorten, motor proteins pull chromosomes to opposite poles of the cell
two poles pushed away from each other
nuclear envelope begins to form around each set of chromosomes
spindle apparatus disintigrates
chromosomes begin to de-condense
(complete mitosis= two independent nuclei formed
cytoplasm divides to form two daughter cells, eash with its own nucleus and complete set of organelles
series of micotubules and proteins define/organize region where new cell membrane will form
cleavage furrow forms from ring of actin filaments that slide and tighten and cause two new cells to pinch off
What are spindle fibers made of?
At what point does the spindle assemble?
Stages at which a spindle assembles and chromosomes attach to it.
prophase- early spindle apparatus forms
prometaphase- kinetechore microtubules conteact chromosomes at kinetechore
region of DNA typically found near the middle of a chromosome where two identical sister chromatids come in contact. It is involved in cell division as the point of mitotic spindle attachment
Attach to chromosomes, attaches to a specific region on the chromosome, same nucleotide sequence in all chromosomes
a barrel-shaped cell structure found in most animal eukaryotic cells, though absent in higher plants and most fungi. The walls of each centriole are usually composed of nine triplets of microtubules
how is entry into the mitotic cycle regulated? what role do each of the following play:
mitosis-promoting factor (MPF) phosphorylates a number of specific proteins needed to intiate mitosis.
cyclin -concentration fluctuates throughout the cell. MPF can be active only when it is bound to cyclin
cycline-dependent kinases is the protein kinase subunit of MPF
MPF phosphorylated in two places. in late G2 phase, it is partially dephosphorylated by enzymes which causes it to be active. triggers events
g.f.- polypeptides that stimulate cell division
noninvasive cells and noncancerous and form benign tumors.
invasive cells from malignant tumors.
cells become malignnat if they gain the ability to detach from the original tumor and invade other tissues
Describe the natural function of restriction enzymes and explain how they are used in recombinant DNA technology
Restriction enzymes splice DNA at specific spots. use same palindromic sequence. Creates sticky ends on linear DNA, binds to plasmid. DNA ligase seals
Outline the procedures for cloning a eukaryotic gene in a bacterial plasmid
- Researchers attach the same palindromic sequences to the ends of each cDNA in their sample as the plasmid
- Cut recognition cites in each plasmid and at the ends of each cDNA with a restriction endonuclease
- Restriction endonucleases make staggered cuts in palindromes. DNA fragments have sticky ends. Plasmid and cDNA bind
- DNA ligase seals the pieces
Describe the role of an expression vector
Generally a plasmid that is used to introduce a specific gene into a target cell
Structure and function of a yeast artificial chromosome (YAC)
Used to clone large DNA fragments. Useful for the physical mapping of complex genomes and cloning of large genes
Two techniques to introduce recombinant DNA into eukaryotic cells
Viruses- inserts its genome into the host
Retroviruses- infect cell, reverse transcriptase catalyzes the production of a DNA copy of the virus’s RNA genome, viral enzymes catalyze insertion of viral DNA into host-cell chromosome
Describe the polymerase chain reaction (PCR). Advantages and limitations
A specific section of DNA is replicated over and over
Sequence information is required. Faster and technologically easier.
arrested stage of development, effectively exited the cell cycle and are sometimes referred to as post-mitotic (nerve cells, muscle cells)
First gap during cell division, organelles replicate and additional cytoplasm is made in preparation for cell division, fist part of interphase before DNA synthesis (7-9 hours)
the phase of the cell cycle between synthesis of DNA (S phase) and mitosis (M phase), the last part of interphase (4-5 hours)
part of interphase, replication of genetic material is separated, in time, from the partitioning of chromosome copies during M phase, the exact chromosome is copied
occurs as vesicles are transported from the Golgi apparatus to the middle of the dividing cell. These vesicles fuse to form a cell plate
Organisms whose cells contain just one of each type of chromosome (n)
Gametes of males and females are (n), made in the testes and ovaries
Those whose cells contain two versions of each type of chromosome (2n) =Diploid cells have one paternal chromosome and one maternal chromosome.
develops in XXY males.
Females with Turner Syndrome have monosomy – their karyotype is XO (they are lacking a second X chromosome) and are usually sterile.
can give an organism incidental unique gene expressions.
Repressible: one whose rate of production is decreased as the concentration of certain metabolites is increased.
Inducible: one whose production can be stimulated by another compound, often a substrate or a structurally related molecule.
- Heritable traits that allow individuals to survie and reproduce in a certain enviornment better than individuals that lack those traits
- results from evolution by natural selection
A limiting factor of adaptation that is the most important constraint.
Ex.: between quality and quantinty of offspring.
The molecular level.
Example: protein shape correlates with their role as enzymes, structural components of the cell, or transporters.
Example: cells that secrete digestive enzymes contain a lot of rough ER and Golgi.
Example: absorptive cells have a large surface area
- cells that are oosley arranged in aliquid, jellylike, or solid extrcellular matrix
- four different types :
loose connective, dense connective, supporting connective, fluid connective
What is the function loose connective tissue?
- found in tendons and ligaments, that connect muscles, bone, and organs; and contains many tough collagen
Has a firm extracellular matrix.
Example: Bone and cartilage, which provide structural support for the body and protective enclosures for the brain and other components of the nervous system.
Fluid connective tissue consists of cells surrounded by a liquid extracellular matrix.
Example: Blood - transports material throughout the body. It's extracellular matrix is called plasma.
Tissues that cover the outside of the body, line the surfaces of organs, and forms glands. Also known as epithelia
- cover the outside of the body, lines the surfaces of organs, and forms glands
- provide protection, regulate transfere of heat between interior and exterior structures, regluate transfer of water, nutrients, etc.
- has a polarity/ sidedness
apical and basolateral sides
The laws of physics affect the anatomy and physiology of organisms in fundamental ways.
Example: physical laws affect body size; body size has pervasive effects on how animals function.
Homeostasis that occurs by conformation to the external enviroment.
Example: the body temperature of Antarctic rock cod closely matches that of the surrounding seawater.
Homeostasis that requires a physiological mechanism that adjusts the internal state to keep it within limits that can be tolerated, regardless of the external conditions.
Example: a dog maintains a body temperature of about 38oC wheter it's cold or hot outside
Epithelium plays a vital role in creating an internal environment that is dramatically different from the external environment and in maintaining physical and chemical conditions inside an animal that are relatively constant.
One of it's most basic functions is to control the exchange of materials across its surfaces in a way that is consistent with homeostasis
What is the role of regulation and feedback?
- any structure that helps restore the desired internal condition
- negative feedback - effectors reduce or oppose the change in internal conditions
Four ways animals exchange heat with environment
What is conduction?
- the direct transfer of heat between two physical bodies that are in contact with each other
- rate conduction occurs depends on surface area of transfer, steepness of temperature difference, and how well each body conduct heat
- special case of conduction
- during conduction heat is transferred between two solids, but during convection heat is transferred between a solid and a liquid or gas
- phase change that occurs when liquid water becomes a gas.
- leads only to heat loss, unlike conduction, convection, and radiation which can lead to heat loss or heat gain
- a lot of energy required to heat water and produce evaporation because of extensive hydrogen bonds
- produces adequate heat to warm its own tissues
- can warm themselves because their basal metabolic rates are very high
- higher metabolizm rates, so can be more active
- relies principally on heat gained from the enviornment
- need to eat less food, so can focus more energy on reproduction
Topor- species that reduce their metabolic rate and allow their body temperature to drop.
Hibernation- torpor that persists for weeks or months
- torpor when small species (high surface area, to low volume) reduce their metabolic rate and allow their body temperature to drop
- torpor persisting for weeks/months = hibernation
Small differences in heat along the length of the exchanger sum up to create a large overall temperature gradient from beginning to end. The longer the system, the greater the overall differential will be
Name the 4 types of Epithelial tissues
Name the 5 types of Connective tissues
In what organ can stratified squamous?
Bronchi of lungs
Where is the Supportive connective tissue found?
- firm extrcellular matrix
- ex. bone & cartilage - provide structural support for the body, and protective enclosures for the brain
Nuclei with blunt ends
Walls of digestive tract
Urinary and genital ducts
Vitam D Synthesis
Epithilial = Stratified Squamous
Connective = Adipose (fat)
Muscular = Arrector Pili
Nervous = Pacinian & Meissner's corpusles
Anatomy - the study of an organisms physical structure
Physiology - the study of how the physical structures in an organism function
- inescapable compromises between traits
- ex. compromise between egg size and egg number
- Adaptation - a genetic change that occurs over generations in response to natural selection in a population
- Acclimation - a phenotypic change in an individual in response to short-term changes in the enviornment
- serves as packing material between the organs, or padding under the skin
- ex. adipose tissue - fat tissue
- cells surrounded by a liquid cellular matrix
- ex. blood - thransports materials throughout the body
- consits of nerve cells - neurons
- projections from nerons:
dendrties - transmit electrical signals from other cells to the cell body
axons - carry electrical signals from the cell body to other cells
- functions in movement
- three types:
skeletal, cardiac, smooth
- responsible for body movements
- consists of long cells called muscle fibers
- makes up the walls of the heart, and is responsible for pumping blood throughout the body
- form a muscle tissue that lines the walls of the digestive tract and blood vessels
- responsible for movements such as the passage of food down the digestive tract
- tissues that contract only in response to unconscious electrical activity
Apical side (epithelial tissue)
Basolateral side (epithelial tissue)
- faces the interior of the animal and connects to connective tissues
- connection made by layer of fibers- basal lamina
- cells w/ similar functions -> tissues -> organs -> organs systems
- organ systems - groups of tissues and organs that work together to perform functions
- As a cell gets larger its volume increases much more rapidly than its surface area
- The rate at which gases, nutrients, and waste products diffuse across a membrane depends on surface area
- the rate at which nutrients are used and waste products are produced depends on volume
- the rate at which an animal consumes oxygen while are rest, with an empty stomach, under normal temperature and moisture conditions.
- small animals have higher BMRs than larger animals
- outgrowths of the body surface or throat used for gas exchange in aquatic animals
- solve problem of water breathing b/c they are a large surface area for oxygen to diffuse across
- requires physiological mechanism that adjusts the internal state to keep it within limits that can be tolerated, regardless of external conditions
- animal is able to regulate the passage/diffusion of water
- ex. humans
- homeostasis that occurs because of conformation to the external enviornment
- osmo-conformer - salt concentration is balanced between that inside and the outside of the system
- ex. fish
- to acheive homostasis animals have regulatory systems that monitor internal conditions such as temperature, blood pH, and blood glucose
- if one of these chances a homeostatic system quickly acts to correct it
- components of a homeostatic system: sensor, integrator, effector
A compound that dissociates into ions when dissolved in water. Conduct electrical currents.
Most common electrolytes in animals: sodium (Na+), chloride (Cl-), potassium (K+), and calcium (Ca2+).
The movement of substances from regions of higher concentration to regions of lower concentration.
- diffusion of water through selecively permeable membranes from areas of higher water concentrations to areas of lower concentration
The movement of water from regions of higher water concentration to regions of lower water concentration, across a selectively permeable membrane.
- the concentration of dissovled substances in a solution
- measured in mol/L
The concentration of dissolved substances in a solution. Measured in moles per liter.
- organisms who actively regulate osmolarity inside their bodies to acheice homeostasis
- such as with fish - tissues hypotonic to salt water enviornment, solution inside cells contains more solute than concentration outside
The process by which living organisms control the concentration of water and salt in their bodies.
It is necessary because organisms need to maintain their set points of water and solute concentrations in order to function.
- driven by diffusion along an electrochemical gradient
- does not require the expenditure of ATP
- move solutes in the same direction
1.) Na+/K+ -ATPase creates an electrochemical gradient favoring diffusion of Na+ into the cell, bringing other ions into the cell w/ no additional energy
2.) Na+, K+, Cl- enter cell powered by Na+ gradient
3.) Chloride channels allow Cl- to diffuse down its concentration gradient into the lumen of the gland
4.) Na+ diffuses into the lumen of the gland, following their charge and concentration gradient
- 80% identicle to the shark chloride channel
- results from a defect in the chloride channel
- a series of tubes extending through the insect body - connects to the exterior through spiracles - which can be closed to minimize water loss
- gas exchange directly across cell membranes - insects dont need circulatory system
- openings through which the tracheae connects with the atmosphere
- can open or close as necessary to minimize water loss
- in order to minimize evaporation from their body surface, insects consists of chitin ( a tough polysaccharide) and a layer of protein
- covered in layer of waterproof wax
- fish dilute ammonia to a low concentration and diffuse it
-humans convert ammonia to less toxic urea and excrete it in urine
- birds, reptiles, and arthropods convert ammonia to uric acid which can be excreted as a dry paste
- there is a fitness trade off between the energetic cost of excreting urea or uric acid and the benefit of conserving water
- blood like fluid
- important becasue : 1.) nitrogenous wastes have been removed before they build up to toxic concentrations 2.) excess electrolytes must be excreted before they lead to osmotic stess 3.) water balance must be regulated constantly
- an excretory organ used to maintain water and electrolyte balance in insects
- responsible for forming a filtrate from the hemolymph ("pre-urine")
- posterior portion of an insects digestive tract, used to maintain water and electrolyte
- "pre-urine" passes from malpighian tubules into the hindgut - it is processed and modified prior to excretion here
- If insect osmotically stressed due to sortage of electrolytes and water - electrolytes and water from filtrate reabsorbed by hindgut and returned to hemolymph
- epithelial cells in hindgut transport ions out of pre-urine into hemolymph - water follow by osmosis creating a concentraed urine
- Chloride pump: Cl- pumped into cells from hindgut lumen, K+ follows through potassium channels along an elctrochemical gradient, and water follows by osmosis
- Na+/K+ - ATPase - in blastoral membrane NA+/K+ - ATPase sets up gradients that favor movement of Cl-, K+, and H2O into the hemolymph
- brings blood containing nitrogenous wastes to the kidney
- basic functional unit of the kidney
- where work involving maintaining water and electrolyte balance occurs
- most located in the cortex
- contains water and small solutes - some waste products, some valuable nutrients
- functions in active transport of selected molecules out of the filtrate
- countercurrent exchanger and multiplier that sets up an osmotic gradient rather than exchanging heat
- osmolarity inside the loop low in the cortex and high in the medulla
- three regions: descending limb, ascending limb, thick ascending limb
- solute moves from loop of Henle to the distal tublue
- fluid slightly hyoptonic to blood and solutes it contains are mainly urea and other waste products
- fluid has reletively constant composition over time
- both types of filtering systems within the kidney
- juxtamedulary nephron - extended loop of Henle - goes deep into the tissue and the medulla
- cortical nephron - no extended loop of Henle
- to maintain homeostasis with respect to water more water may be reabsorbed in the collecting duct
- Urea leaves the base of the collecting duct and contributes to the osmotic gradient set up by the loop of Henle
- nephrons final portion
- urea diffuses out of the inner most section of the collecting duct, creates a steep osmotic gradient of the space surrounding the nepron - high in inner medulla, low in outer medulla
- urine formation starts here
- made up of the glomerulus and bowman's capsule
- small projections of the epithelial cells of the proximal tubule
- when valuble solutes leave proximal tubule and enter microvilli, water follows - important solutes and water rabsorbed and returned to body
- water leaves the proximal tubule through these membrane proteins
- water channels
- highly permeable to NA+ and Cl-, moderatly permeable to urea, and almost completly imperemeable to water
- loop of Henle maintains an osmotic gradient because water leaves the decsnding limb, and salt leaves the ascending limb
- osmolarity of surrounding solution is low - additional Na+ and Cl- ions are actively transported out of the nephron
- associated network of blood vessels
- water and salt that move out of the loop quickly diffuse into the vasa recta
- if Na+ levels in the blood get too low adrenal gland releases hormone aldosterone which leads to the activation of sodium pumps and reabsorption of Na+ in the distal tubule
- Alsoderone saves sodium
- released from the adrenal cortex when ion concentrations in body fluids are low
- resulting in increased reabsorption of sodium ions in the distal tubules of the kidney
- brain releases ADH if an individual is dehydrated
- ADH saves water
- triggers the insertion of aquaporins into the apical membrane - cells become more permeable to water, and more water is absorbed
- increases permeability to urea - increases osmolarity of the surrounding fluid and thus water loss from the filtrate
- obtain energy and nutrients they need from other organisms rather than making their own food
- processes needed to obtain energy from food: ingestion, digestion, absorption, and elimination
- plants - make thier own food
- they can synthesis glucose and carbohydrates
- a substance an organism needs to remain alive
- orgainic compounds that are essential to health but are required only in small amounts
- several function as coenzymes in critical reactions
- essential vitamins: vitamin B1, b12, niacin, folate, vitamin C, and D
- mouthparts have diversified in response to natural selection for exploiting a diversity of food sources
- the sturcture of jaws, teeth, and other mouthparts correlates with their function in harvesting and processing food
- also called alimentary canal or gastrointestinal (GI) tract
- two geneal designs: incomplete and complete
- single opening that doubles as the location where food is ingested and wastes are eliminated
- mouth opend up to chamber called gastrovascular cavity where digestion takes place
- two openings - start at mouth and end at anus
- interior of this tube communicates directly with external enviornment via these openings
- allows animals to feed on large pieces of food
- different chemical and physical processes can be separated within the canal so they occur independently of each other and in a prescribed sequence
- material can be ingested and digested continuously instead of in batches
- three major types of macromolecules - carbohydrates, lipids, and proteins - must be broken down during digestion --> starts in mouth, then stomach, finishes in small intestine
- small molecules porduced from this absorbed in small intestine along w/ water, vitamins, and ions
- more water absorbed in large intestine, producing feces
- in the mouth - release glycoproteins called mucins
- when mucins contact water they form mucus
- food is propelled through the esophagus by a wave of muscle contractions
- this system is a reflex triggered by swallowing
- tough, muscular pouch bracketed on both ends by valves called sphincters
- after eating muscular contractions in the stomach result in churning that mixes and breaks down the food mechanically
- lumen of stomach highly acidic - predominantly HCl in stomach
- enzyme found in high concentrations in parital cells
- catalyzes the formation of carbonic acid from water and corbon dioxide
- in solution it immediatly dissociates into a bicorbonate ion and a proton
- the protons formed are actively pumped into the lumen of the stomach
- species that have a stomach specializedfor digesting cellulose instead of protein
- can harvest this energy form cellulose due to combination of specialized anatomical structures andsymbiotic relationships with bacteria and other unicellular protists
- adjacent to the rumen - both have symbiotic bacteria and protists which can break down cellulose
- after partial digestion the rumiant regurgitates portions of the plant into the animals mouth, forming a cud, the animal then chews the cud and re-swallows it
- type of modified stomach
- birds dont have teeth so they can't chew - instead most swallow sand and stones that pulverize food as the muscular gizzard contracts
- 6 meter long tube where food mixes with secretions from the pancreas and liver
- at the digestion is complete end most nutrients, including water have been absorbed
- projections on the small intestine that allow it to have a large surface area for absorption
- they in turn have projections called microvilli
- ensymes in the small intestine that digest polypeptides to momomers
- synthesised in inactive form by the pancreas and transferred through the pancratic duct to the small intestine where they are activated
- enzyme that activates pancratic enzymes
- specifically trypsinogen through phosporilation resulting in the active enzyme trypsin --> activates other enzymes that are synthesized and secreted in an inactive form
- when activate each enzyme cleaves specific peptide bonds