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Cell Cycle

Cell Cycle. Cell Cycle. Cell proliferation Cell division is unique to eukaryotes. Origin of replication. E. coli cell. Two copies of origin. Chromosome replicates one copy of the origin moves to the end of the cell. 1. Replication continues. 2. Origin. Origin.

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Cell Cycle

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  1. Cell Cycle

  2. Cell Cycle • Cell proliferation • Cell division is unique to eukaryotes

  3. Origin of replication E. coli cell Two copies of origin • Chromosome replicates • one copy of the origin moves to the end of the cell 1 Replication continues 2 Origin Origin • Replication finishes • plasma membrane grows inward 3 4 Two daughter cells result Binary Fission

  4. Functions of Cell Division • Reproduction • Ex. amoeba • Growth & development - embryo • Renewal & repair -bone marrow cells Sand dollar embryo Bone marrow cells

  5. Distributes identical genetic material 2 daughter cells

  6. Two main stages: • Interphase - Gap 0 (GO)‏ - Gap 1 (G1)‏ - S (synthesis) phase • Gap 2 (G2)‏ • M phase • Mitosis • Cytokinesis

  7. 0.5 µm Before cell division Chromosomeduplication(including DNA synthesis) Centromere Duplicated chromosome Sisterchromatids Separation of sister chromatids Chromosome distribution Centromeres Sister chromatids Figure 12.4 What happens in Cell Division

  8. RNA & protein synthesis & growth 20-22 hours (mammalian tissue) Interphase

  9. Gap 0 • cell leaves the cycle & quits dividing • temporary resting period or more permanent • Example: mature neurons, muscle cells

  10. Gap 1 phase • Cells grow in sizeand do their ‘job’ • preparation for S phase • G1 Checkpoint (control mechanism) • 5-6 hours

  11. G0 G1 checkpoint G1 G1 (b) If a cell does not receive a go-ahead signal at the G1checkpoint, the cell exits the cell cycle and goes into G0, a nondividing state. (a) If a cell receives a go-ahead signal at the G1 checkpoint, the cell continues      on in the cell cycle.

  12. S phase • DNA replication occurs • Cell grows more • 10-12 hours

  13. Gap 2 phase • cell grows & organelles replicate • preparation for mitosis • 5-6 hours • G2 Checkpoint

  14. Experiments showed… S G1 M G1 S S M M

  15. G1 G1 M G2 G2 S S M M MPF activity Cyclin Time G1 S Cdk M G2 DegradedCyclin G2checkpoint Cdk Cyclin is degraded Cyclin MPF Cell Cyle Control System • Cyclin-dependent kinases • Constant • Cyclin • fluctuates • MPF (Mitosis-promoting factor)‏ • Triggers mitosis • Destroys cyclin

  16. Intermission Number!

  17. Mitosis Waltz by: MoxyFrvous [In thick German accents] If it's ze secrets of life that you seek Zen srough (through) a mi-croscop you must peek! Mendel did vonders just using his eye, But to really see, you must magnify You can't help but notice ve'renossing (nothing) but cells, But vhere in ze cell does heredity dvell? The Nu-cleus! That's vhere it hides. You don't see much until it divides, Then Chro-masomes enter new phases, Split into two, und zat is ze basis Of Sexual Transmission vhicholvays engrossesOur feverish minds, but it's only Meiosis.Reducing zee chromasomes fifty percent,So vhen egg and sperm meet at zat blessed event,ZeChro-masomes form one full set.Just two of each kind, zat'sze best best!And that new cell begins to grow,Multiplies into an Em-bryo.Ze ex-plana-tion of zis growthIs it's due to a process ve know as Mitosis!And zat'svhat our Microscopes helped us determine,In Germany, vhere un ze germ cells are German!

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