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UW-Madison BIOLOGY 151 - Mitosis and Meiosis

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BIO 151 1st Edition Lecture 18 Outline of Last Lecture 1. Movement to and from ER and Golgi via transport and secretory vesicles2. "Trafficking" of vesicles3. Movement of vesicles - not simply diffusion4. Cytoskeleton in eukaryotes 5. Microtubules6. In animal cells, microtubules often emerge from pair of centrioles in centrosome7. Microfilaments8. Intermediate filaments9. Coat proteinsOutline of Current Lecture 1. Coat proteins2. Prokaryotic cell division3. Eukaryotic chromosomes4. Mitosis5. Mitotic spindle arranges and moves chromosomes6. How does the mitotic spindle work?7. Cytokinesis8. Cytokinesis different if there is a cell wall9. The cell cycle10. Cell cycle checkpointsCurrent Lecture - cytoskeleton drives cell division and chromosome movement in eukaryotesCoat proteins:- help shape and traffic membranes, vesicles - ClathrinProkaryotic cell division:- DNA (and associated proteins) in single circular chromsome- replicate chromosome- divide cell by fission into 2 "daughter" cellsEukaryotic chromosomes:- linear DNA in a complex with proteins- set number in each species (we have 46 per cell)- different chromosomes contain different genes- need to get 1 copy of each chromosome to each daugher cell- eukaryotic cell division - multiple chromosomes- mitosis - daughter cells have the same number of chromosomes as the parent cellThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- meiosis - daugher cells have half the number of chromosomes as the parent cell - need before fertilization- DNA replication produces 2 sister chromatids, joined at the centromere (center of chromosome)- when joined, called single chromosome with 2 chromatids- separation during mitosis into 2 chromosomes- one chromosome with 2 sister chromatids- chromosome does not equal amount of DNA- a chromatid has 1 DNA double helix- one chromosome may have 1 or 2 DNA double helixes (before or after replication)Mitosis:- separate sister chromatids to separate chromosomes- after replication, 2 double-stranded (double helix) chromatids attached into single chromosome at centromere, ends are telomeres- microtubules organized by centrosome with 2 centriolesMitotic spindle arranges and moves chromosomes:- microtubules -in non-plant cells, radiating from 2 centrosomes each with paired centrioles- some spindle microtubules attached to chromosome centromeres - mitosis in "phases" --prophase, metaphase, anaphase, telophase-prometaphase - break down nuclear envelope, chromosomes shoved together along mid-line-metaphase = condensed plate, still have sister chromatids attachedHow does the mitotic spindle work?:- kinetochore - proteins surrounding centromere, control movement by:- shortening: microtubules disassembled at kinetochores and sometimes the poles- also, sliding using motor proteinsCytokinesis:- subdivision of the cytoplasm into 2 cells- animal cells form cleavage furrow- requires contractile ring of underlying microfilaments and myosinCytokinesis different if there is a cell wall:- plant cells are inside a cell wall- form a new membrane from vesicles fusing in middle of cell = cell plateThe Cell Cycle:- DNA replication = synthesis or S phase- division during mitotic or M phase- GAP 1 (G1) = period between M and S phases- GAP 2 (G2) = period between S and M phasesCell Cycle Checkpoints:- G1 - cell large enough, nutrients (fat and happy), signals?- G2 - happy, DNA duplicated- M - chromosomes attached to cytoskeleton for movement- MPF = complex of 2 proteins, drives cell through G2 checkpoint- cyclin protein concentration increases as cell ages, but when too high triggers its own destruction- cyclin binds and activates: Cyclin-Dependent Kinase (CDK) protein to create active MPF- active kinase attaches phosphate to target proteins, charges their


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UW-Madison BIOLOGY 151 - Mitosis and Meiosis

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