Intro Zoology week 9 notes
Intro Zoology week 9 notes BIOL 1114, 001
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This 4 page Class Notes was uploaded by Hannah Kirby on Sunday March 27, 2016. The Class Notes belongs to BIOL 1114, 001 at University of Oklahoma taught by Dr.Lee in Winter 2016. Since its upload, it has received 14 views. For similar materials see Intro to zoology in Biology at University of Oklahoma.
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Date Created: 03/27/16
Zoology notes week 9 Ch. 3, 8 Apoptosis programmed cell death DNA replication before mitosis cells double up before dividing (otherwise daughter cells would be smaller and smaller) Mitosis cell cycle control = traffic signs Cancer cells ignore traffic signs Metastasis = cancer cells go motile (cell adhesion) Two types of cell division in sexual life cycle Mitosis cell division; identical DNA Meiosis production of gametes; ½ DNA o Male and female gametes come together to form the zygote Mitosis has many roles Growth Repair Regenerate Reproduce (Asexual) Mitosis and apoptosis work together Motitic division adds new cells, apoptosis removes cells What if cells don’t die? Cancerous growth (Injured cell doesn’t die, but continues to grow out of control) Dna replication before cell division Each daughter cell= identical DNA Genome= all of the cells genetic material (over 3 billion base pairs) DNA replication = DNA to DNA (in transcription, only one strand is used as a template; during replication, both strands serve as templates simultaneously) DNA replication can occur at multiple origins, eventually combining to form the two daughter strands Enzymes participating in DNA replication Helicase unwinds the double helix; creates replication fork Binding proteins stabilize each strand, hold the strands apart Primase adds short RNA primer sequence to the DNA template (temporary) and DNA polymerase will bind to the primed (RNA segment) region DNA polymerase recognizes primers; binds nucleotides to form new strands of DNA (complementary) top and bottom strands move in opposite directions; leading strand follows the helicase and is continuous; lagging strand will eventually end and form Okazaki fragments Ligase RNA primers are replaced with DNA, and ligases fill in the gaps; joins Okazaki fragments and seals other gaps in sugarphosphate backbone Binary fission an asexual process that replicates DNA and distributes it to two daughter cells Eukaryotic cells have to duplicate the nucleus before the cell can divide DNA condenses into chromosomes Histomes begin winding DNA strand to form nucleosomes DNA continues to wrap and forms chromatin Chromatin compacts more and forms chromosome (distinct structure) Sister chromatids identical chromosomes after DNA replication Centromere structural region of chromosome attaching point and forms the “X” o not to be confused with centrioles or centrosomes DNANucleosome chromatin chromosome Cell cycle during division Figure 8.10 Interphase: growth, double up genetic material, double up on cytoplasmic components G1 phase: newly divided cell grows, protein synthesis occurs, normal cell function G0 phase: normal function, not dividing, no replication, most cells are currently in G0 S phase: DNA replication G2 phase: produces proteins required for mitosis (spindle proteins, membrane proteins) After G2 phase Mitosis: division of nucleus (prophase, prometaphase, metaphase, anaphase, telophase) Cytokinesis: division of the cell Chromosomes divide during mitosis fig 8.21 DNA replication occurs during S phase; interphase DNA condenses during prophase Chromosomes line up at the cell equator during metaphase Centromere splits during anaphase Steps of mitosis: Prophase chromosomes condensing Prometaphase nuclear envelope is gone, centrosomes are on opposite sides of the cell Metaphase centrosomes align at equator, spindle fibers attach Anaphase centrosomes split equally by spindle fibers, sister chromatids separate and move to opposite poles of cell, poles move further apart Telophase spindle fibers detach, nuclear envelope reforms, chromatids decondense Cytokinesis cell splits into two daughter cells; cytoplasm splits Contractile ring forms cleavage furrow Cytoskeleton network of protein tracks and tubules o Microfilaments actin molecules (compose contractile rings, cilia, flagella) o Intermediate filaments protein subunits o Microtubules tubulin subunits (compose mitotic spindle fibers) Structural support Aids in cell division Organelle transport Cell movement Checkpoints: G1 checkpoint: Is DNA damaged? S checkpoint: Is DNA replicating correctly? G2 checkpoint: Has all DNA replicated? Can damaged DNA be repaired? Is spindle making machinery in place? Metaphase checkpoint: is spindle built? Do chromosomes attach to spindle? Are chromosomes aligned down equator? If any of these do not pass= APOPTOSIS Cells Adhesion proteins hold cells together tight junctions, anchoring junctions, gap junctions all hold cells together A tumor is an abnormal mass of tissue Tumors arise from: 1. Overactive protooncogenes 2. Underactive tumor suppressor genes (p53) Apoptosis has 2 functions: 1. Eliminates excess cells; carving out structures 2. Weeds out aging or defective cells Cancer cells: 1. Ignore mitotic checkpoints 2. Overactive oncogenes 3. Underactive tumor suppressor genes 4. Ignore apoptotic signals 5. Ignore contact inhibition 6. High telomerase activity 7. Lose adherence to others 8. Ignore other cell signals
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