Lecture 2

StudyBlue printing of Lecture 2 html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, font, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td { margin: 0; padding: 0; border: 0; outline: 0; font-size: 100%; background: transparent; } body { line-height: 1; } blockquote, q { quotes: none; } blockquote:before, blockquote:after, q:before, q:after { content: ''; content: none; } /* remember to define focus styles! */ :focus { outline: 0; } /* remember to highlight inserts somehow! */ ins { text-decoration: none; } del { text-decoration: line-through; } /* tables still need 'cellspacing="0"' in the markup */ table { border-collapse: collapse; border-spacing: 0; } /* end RESET */ .header { min-width:800px; } .logo { padding:6px 20px 2px 20px; margin:0; font-size:25px; font-weight:bold; 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-moz-border-radius: 5px; -webkit-border-radius: 5px; } .print-button a:hover { background-color:black; } .theNote .content { width: 8.0in !important; margin: 5px auto; padding:20px; background-color:white; } .theNote .header { border-bottom: 1px dashed #C8C8C8; font-size: 17px; padding: 0 0 10px; line-height: 19px; color: #00ADE1; min-width:500px; } .theNote .body { font-size: 14px; line-height: 19px; padding: 10px 0; } .theNote{ padding:6px 0; clear:both; background-color: rgb(200,200,200); } .theNote h3{ color: rgb(100,100,100); } .theNote h1, .theNote h3{ background-color:white; padding:2px 20px; width:8.0in !important; margin: 0 auto; font-size: 15px; } .theNote h1{ padding-top: 10px; font-size: 15px; } .theNote h1:first-child{ font-size: 20px; } .theNote h3 { font-size: 14px; font-weight: normal; } #options { border: 3px double #ccc; padding: 5px 12px; margin: 10px 50px 10px 20px; float: left; } #info { border-top: 1px solid #ccc; padding-top: 5px; font-style: italic; } li { margin: 5px 10px 5px 25px; } ul li { list-style: disc; } ol li { list-style: decimal; } img { border: 0; } table { clear: both; width: 100%; border: 1px solid #c5c5c5; border-width: 1px 0; margin: 0; page-break-after: always; } table#page { page-break-after: auto; } td { text-align: center; font-size: 12px; border-bottom: 1px dashed #c5c5c5; height: 1.75in; width: 50%; padding-left: 15px; } .leftside { border-right: 1px solid #cccccc; padding: 0 15px 0 0; } .bottom td { border-bottom: none; } .clearfix { clear:both; line-height:1px; height:1px; } img { max-width:80%; max-height:150px; margin:20px; } @media print {.header { display: none; } .content .header{ display:inherit; } table { border: 1px dashed #bbb; border-width: 1px 0; } .theNote{ background-color:white; } } Lecture 2 cells have to maintain their own existance- programmed and conducted by the cell, and have to contribute to the funcationality of the organism Cytoplasmic Organelles- - cytoplasm-(responsible for cell activity, divided into regions for specific function) cellular material inside of the cell; includes the Cytosol- fluid in which other components are suspended, and organelles (most are membrane bound) - of the cells organelles theres a collection of organelles whos job is to make proteins- also known as the endo-membrane system within the nucleus of the cell is the genetic material that specifies all functions of the cell all the functions to maintain the existance of the cell plus any specific products that need to be made by the cell and released by the cell; the DNA is not portable but contained within the dna are specific regions; - the DNA is Transcribed into a protable message called MRNA- which contans the instructions for the production of the proteins the MRNA leaves the nucleus enters into the outside and enters the endoplasmic reticulm the components of the cell that are involved in expressing the gene are components of the endomembrane system, but not all the cells in the endomembrance system are involved in m i. Chromosomes cluster at the middle of the cell m aking proteins DNA______________> transcribed____________> converting DNA to MRNA__________> leaves the nucleus through an opening called the nuculer pore____> now it is outside, it enters the endoplasmic reticulum specifically the rough ER bc of the irregular surface, this surface is actually another organelle called the Ribosome - there are two classes of proteins being made by cells: 1. secretory protein made by the endomembrane system (releases from the cell) 2. free ribosomes make proteins that stay inside the cell Secretory Proteins- rna is released outside of the nucleus and enters into a series of folded membranes called the endoplasmic reticulm- and inside the ER are specific conditions that can perform specific type of functions; the MRNA has to be converted into proteins and the organelle responsible for the conversion is the - Ribosomes - which binds the MRNA read the code and uses the code to synthesizes the proteins molecules; once the proteins are synthized it is passed within the endoplasmic reticulum collecting along the way other components and then packaged into another organelle called the transport vesicle- now the protein is transported into another organelle called the Golgi apparatus- which is a series of folded up membranes and within those folds are specific cellular environments that act upon the protein- emerges out of the golgi in its form into the secretory vesicles to the surface of the cell now the protein can either be intergrated into the pm or can be secreated so the endomembrane system is comprised of the Rough ER, including the ribosomes- the transport vesicle, the golgi apparatus, and the secretory vesicle not all ribosomes are associated with the rough ER,some are free inside the cell and these ribsomes can read the mrna and can produce proteins but they are never secreted they are used inside the cell itself Not all ER is rough there is ER that has no ribosomes and this is called the Smooth ER because of the lack of ribosomes it cannot make protein, but it can synthize lipids, modify carbs, can break down drugs and can store calcium inside the cell the building blocks of animals are: proteins- made by the ribosomes that are either free or on the rough er carbs- associated with the smooth ER lipids- associated with the smooth ER nuclaic acids-not synthised within individual cells the endomembrane system includes rough and smooth er, ribosomes, golgi, transport and secretory vesicles: there are other organells included in the endomembrane but do not participate in the production of proteins i.e. Lysomes- digstive enzymes that digestive certain material that needs to be broken down ; contained inside of specialized regions (cellular level) Vacules- a fluid filled or pressurized gas filled membrane that gives the cell structure -animal cells have an internal skeleton -peroxisome- is a compartment for certain types of chemicals which would damage cellular components -the mitochondria (not in the endomembrane system) -most cells have more than one; it is the region in the cell where cellular energy is produced; at a macoscopic leval organisms consume food out of the environment then use digestive properties to break the food down into macromolecules, then the release of the chemical energy found in those macromolecules is done enzymatically within the cells themselves; one process is called cellular respiration -the mitochondria is also a membrane bound organelle that has an outter membrane then an inner membrane and the space between the outter and inner membrane is involved in a proton pump; the inner space is called the matrix and the folds are called the crista - the motochondria release energy from chemical bonds- then energy is stored in ATP- then ATP is broken down to ATP+pi which releases that energy which can drive other chemical reactions cellular structure of animals -either the cells are connected mechanically: 3 ways structural connection via the desmosomes tight junctions- no materials can flow through gap junction- materials of the internal environment of 2 neighboring cells are in contact with each other; sometimes called an interculated disc if in the heart- it allows not material but electrical current to pass from one cell to another -most of the body are close enough to be connected but outside of the cell is an extracellular matrix and this matrix is comprised of fibers and fluid(sometimes called ground substance) and cells will be attatched to the extracellular matrix; the structure is based on the fibers and fluids cells also have internal skeleton that gives structure - cytoskelton inside are the cyntrosomes which are a combination of centrisoles and astids and connected to the centriosomes are microtubules that extend from the centriosomes out on to the plasma membrane the microtubles: give structure , attatch to the central component of the cell and attatch to the perephial component of the plasma membrane, and they act as tracks for organelles to move along the microfilaments they line the inner surface of the cell made up of a contractile protein called Actin- which allows the cell surface to become smaller when contracted, or expand when it is relaxed the intermediate filaments act as guy wires to resist pulling forces on the cell fix organelle position The Nucleus has two membranes like most organelles and the nucular membrane is a lot like the plasma membrane, periodocially the membrane is spanned by an opening called the nuclear pore inside of the nucleus is the genetic material of the cell which is DNA, now the dna inside the cells is not chromosomes, chromosomes are only present when the cell divides, the dna is called chromatin, chromatin is simply the dna wrapped around a protein molecule called histone this makes the dna very organized; dna+histone= chromatin there are also areas called nucleoli- which are not surrounded by membrane, the primary function is where the subunits of the ribosomes are made for most organisms the nucleus is a diploid nucleus, Ploid means how many types or how many sorces of dna are there in the nucleus. humans have 2 copies of the complete genome inside of most nucli of cells and those copies are from 2 sources= 2N2n The Life Cycle of a Cell -the cell cycle includes all events from a cell's formation until it divides, the cell cycle includes 2 major periods: interphase and mitosis (cell division) -most of the cells life is spent in interphase, everything that is not division is interphase, interphase is divided into subphases: G1 phase- the cell is performing its basic functions , so whatever that cell's fuction is in the larger organism is being performed while in G1, some cells do not divide very often and will leave G1 and enter a subphase of G1 called G0, g0 is a perpetual phase of G1 S phase- synthetic phase, dna is replicated during this phase, G2 phase-the cells have to return to a g phase, and the organelles are duplicated, in addition unique cellular components are made that are required for division: (brief period of growth where enzymes and other proteins necessary for division are synthesized) -after the cell undergos these changes then division can begin Cell Division there are two types of cellular division: Mitosis and Meiosis - mitosis is the division of somatic cells (body cells)- type of division used to duplicate body cells -Meiosis- is the division for reproduction 2. The next difference is the number of daughter cells: -mitosis- there are 2 daughter cells produced -meiosis- there are 4 daughter cells produced 3. the next difference is the genetic makeup of the daughter cells produced: -mitosis- the daughter cells are clones of the original parent cells, the original parent cells are diploid, so daughter cells are diploid and have a 2N2n composition -meiosis- the daughter cells produced are genetically unique from the original parent cells, they may be genetically unique from eachother, but it is possible to produce gamets that are clones of eachother, the daughter cells are haploid having one copy of the genome from one source 1N1n 4. another difference is the number of times the nucleus divides: -mitosis- the nucleus only divides once -meiosis- the nucleus divides twice 5. the last difference is whether a genetic event takes place during division called synapsis- synapsis is a process in which genetic information is exchanged between chromosomes sometimes refered to as *crossing over -mitosis- this event doesnt occur during this type of division, because the cells are identical it would not make a difference if this occured -meiosis- this frequently occurs, and genes are exchanged between maternal and paternal chromosomes creating unique chromosomes that never existed Phases of Mitosis reference the scaned pages for understanding the cells go through s phase and g2 now it is ready for division, so at the end of g2 the cell looks like a normal cell, but at this point within the nucleus there are not 2 copies of the genome, but now 4 copies of the genome, it is still chromatin, the nuclear membrane is present, now the cells proceed into division which is a continuous process, there are 4 subphases of motosis: Prophase- i. Prior to the start of prophase, centrioles have replicated (two pairs) ii. Chromatin condenses to form chromosomes iii. Chromosomes already replicated and consist of two sister chromatids iv. Sister chromatids are connected by centromere v. Nuceoli disappear ` vi. Centriole pairs are rearranged to focal loci for mitotic spindles (microtubules) vii. Nuclear membrane disappears and spindles interact with chromosomes viii. Spindles attach to kinetochores (proteins on centromere) ix. Kinetochore microtubules pull chromatids to center of the cell metaphase- i. Chromosomes cluster at the middle of the cell ii. Metaphase plate anaphase- i. Centromeres of the chromosomes split ii. Each chromatid is now a chromosome iii. Kinetochore fibers contract and pull chromosomes towards poles iii. Poles of cells are pushed apart to elongate the cell iv. V-shaped v. Shortest stage; minutes telophase- i. Chromosome movement stops ii. Chromosomes uncoil to form chromatin iii. Nuclear membrane reforms iv. Nucleoli reform v. Spindles disassemble Cytokinesis- peripheral microfilaments contract at the cleavage furrow to squeeze the cells apart Meiosis (Chapter 28): gamete production; two consecutive divisions produce four daughter cells each with half as many chromosomes as mother cell 1. Nuclear divisions: Meiosis I and meiosis II 2. Meiosis I (preceded by interphase where DNA is replicated): Reduction Division a. Prophase I i. Chromosome form, nuclear membrane and nucleolus disappear ii. Synapsis: homologous chromosomes form tetrads; crossover points form (chiasmata) b. Metaphase I i. Tetrads align on equatorial plate c. Anaphase I i. Centromeres do not break (sister chromotids remain paired) ii. Homologous chromosomes separate, breaking at crossover points (exchange parts of chromosomes) iii. Paternal and maternal chromosomes are separated d. Telophase I i. Same events as telophase of mitosis ii. Cytokinesis follows iii. Daughter cells are haploid (Diploid amount of DNA but haploid chromosomal number) 3. Meiosis II (Like mitosis without DNA replication during interphase) a. Four daughter cells are produced each genetically unique from original mother cells Cancer A. Neoplasia—increase in new cells 1. Dystrophy—disorder arising from abnormal change in cell size a. Hypertrophy—increase in size of cells 2. Dyplasia—disorder arising from abnormal change in cell number a. Hyperplasia—increase in number of cells b. Aplasia—decrease in cell number i. Normal during development ii. Occurs later in life (e.g., dementias, osteoporosis) B. Tumor—unchecked growth of genetically abnormal cells 1. Classification based on characteristics a. Benign i. Looks like normal tissue ii. Grows slowly iii. Does not invade b. Malignant: Cancer i. Poorly differentiated ii. Grow fast iii. Invasive iv. Metastasize 2. Classification based on origin a. Carcinomas—epithelial origin i. Glandular ii. Squamous iii. Melanocyte b. Sarcomas—connective tissue origin i. Cartilage ii. Bone iii. Fibrous connective iv. Meninges 3. Classification based on prognosis or therapy a. Tumor mass b. Lymph involvement c. Metastasis C. Epidemiology—cause of disease; factors that lead to cancer For a few rare situations, there are known genetic defects (e.g., retinoblastoma) or viral agents (e.g., Burkitt’s lymphoma). But for most other cancers, the specific cause is not known. A. Risk factors 1. Host factors a. Age b. Sex c. Psychological factors d. Genetic factors 2. Environmental and lifestyle factors a. Geographic location b. Nutrition c. Occupation i. Asbestos ii. Pesticides iii. Radiation d. Cigarette smoking D. Etiology 1. Cancer has no single cause. Its etiology is complex, requiring both: a. DNA damage b. Inadequate physiological defense or repair 2. Initiation of cancer— Neoplastic Transformation a. Arise from a single cell b. Cell suffers multiple transforming genetic mutations i. Mutations are either inherited or acquired 3. Acquired mutations a. Random events during DNA replication b. Induced by mutagens ( carcinogens ) 4. Initial DNA damage promotes accumulation of further damage a. Damage typically involves genes that normally: i. Induce cell proliferation or growth ( proto-oncogenes ) ii. Inhibit growth of damaged cells ( tumor suppressor genes ) E. Treatment 1. Surgery—resection of the tumor 2. Radiation therapy—x-rays or gamma rays delivered to the tumor; induce apoptosis in radiosensitive cells (including normal cells) 3. Chemotherapy (antineoplastic agents)—cytotoxic drugs that induce DNA damage; normal cells are often better at repair and less vulnerable to apoptosis 4. Bone marrow transplantation—certain cancers require high doses of radiation or chemotherapy; such treatment is toxic to bone marrow 5. Biological response modifiers—agents that boost immune system response or antagonize tumor growth through other biological effects (e.g., interferon, cytokines, etc.) 6. Gene therapy—modify gene function; include synthetic nucleotide strands to repair DNA, antisense strands to prevent gene expression, insertion of gene sequences to produce normal gene products