1. Cell Division

2. Multicellular life starts as a single cell Growth, development and reproduction require cells to divide and replicate themselves

3. Types of Cell Division Binary Fission –Replication and division in Prokaryotes Mitosis –Replication of a cell to produce identical daughter cells Meiosis –The creation of gametes for sexual reproduction

4. Quick Refresher – Binary Fission The prokaryote replicates its single chromosome The cell continues to grow and eventually splits into two cells

5. Cell Cycle The process of cells growing, replicating and dividing Can take minutes, hours, or up to a year to cycle through (most about 1 day) Some cells cease to grow and divide and are no longer part of the cycle –Ex. Heart, eye, nervous system

6. Cell Cycle Consists of two main stages –Interphase –Mitotic Phase

7. Cell Cycle The interphase is divided into 3 parts –Gap 1 (G1) –Synthesis (S) –Gap 2 (G2)

8. Cell Cycle - Interphase G1 –The cell grows in size and produces RNA and synthesizes proteins S –The cell continues to grow, and replicates (synthesizes) it’s DNA G2 –The cell continues to grow and prepare for mitosis

9. Cool Fact It takes approximately six hours to replicate the entire human genome That is 6,000,000,000 (six billion) nucleotides that must be kept exactly the same as the parent cell Mistakes in this replication lead to mutations

10. Mitotic Phase Divided into two main parts –Mitosis Division of the nuclear material –Cytokinesis Division of the cytoplasm

11. Cell Cycle Control Errors in cells growth can lead to uncontrolled division and development –This is how tumors can develop Proteins in the cytoplasm of a cell regulate the cell cycle When working properly, this prohibits the cell from replicating if conditions are not ideal, or there are errors in DNA

12. Cell Cycle Control There are three main checkpoints in the cell cycle –G1 Checkpoint –G2 Checkpoint –M Checkpoint There are also control mechanisms in the S phase

13. Cell Cycle Control Main proteins involved –Cyclins –CDKs –MPF (maturation promoting factor) –p53 –p27

14. Cyclins Levels within the cell rise and fall through the cycle G1 (cyclin D) S (cyclin E and cyclin A) M (cyclin B and cyclin A)

15. CDKs Levels remain relatively constant in the cell Bind with cyclins to be activated G1 to S CDK4 S CDK2 G2 to M CDK1

16. Other Control Proteins MPF – promotes movement from G2 to M p53 – can stop cell cycle if damage is present for either repair or apoptosis (cell death) p27 – a protein that can bind to cyclin and CDK stopping entry to S phase

17. http://www.cellsalive.com/cell_cycle.htm http://highered.mcgraw- hill.com/sites/0072495855/student_view0/c hapter2/animation__control_of_the_cell_cy cle.htmlhttp://highered.mcgraw- hill.com/sites/0072495855/student_view0/c hapter2/animation__control_of_the_cell_cy cle.html

18. Cell Cycle Homework Draw the cell cycle and label each stage and checkpoint Describe in your own words what is happening at each stage, and each checkpoint

19. The Chromosome Chromosomes are the condensed form of the nuclear Chromatin Eukaryotes generally have two copies of each chromosome In humans that is 46 total chromosomes We call a cell with two full sets of chromosomes 2N or Diploid

20. The Chromosome During cell division chromosomes replicate When they are replicated each chromosome is called a chromatid The region of DNA that joins them is called the centromere Covering the centromere is the kinetochore

21. Label the Following Diagram Kinetochore Centromere Chromatid

22. Important Structures Spindle – a collection of microtubules that connect the centrosome to the kinetochore Aster – a collection of microtubules that connect the centrosome to the cell membrane

23. Important Structures Centriole – a cylindrical rod of microtubules found only in animal cells Centrosome – a condensed portion of cytoplasm that organizes microtubules. In animal cells it contains the centrioles.

25. Mitosis The separation of the nuclear material in a cell Divided into 5 phases –Prophase –Prometaphase –Metaphase –Anaphase –Telophase

26. Prophase Chromatin condenses to chromosomes Nuclear envelope dissolves Centrioles divide and migrate to opposite ends of the cell Microtubules begin to form from the centrosome

28. Prometaphase Centrioles finish their migration Proteins attach to the centromere to create the kinetochore Microtubules emerge from the kinetochore and connect to the centrosome Microtubules connect each centrosome creating the spindle Microtubules connect the centrosome to the cell membrane creating the aster

30. Metaphase Spindle fibers line up sister chromatids along the center of the cell called the Metaphase Plate The M Checkpoint happens at this time, ensuring the chromosomes are properly lined up so one chromosome enters each daughter cell

32. Anaphase Spindle fibers pull apart the sister chromatids Chromatids migrate to opposite sides of the cell

34. Telophase Chromatids arrive at opposite ends of the cell Chromatids disperse back to chromatin Spindle disperse Cleavage furrow (animal cells) begins to form Cytokinesis begins

36. In animals, a ring of microfilaments contracts until it finally pinched the cell in half. In plants, portions of cell wall contained in membrane vescicles (circles) condense to form a plate (or wall).

37. Stages of M phase

39. Early Prophase

40. Prometaphase

41. Metaphase

42. Early Anaphase

43. Late Anaphase

44. telophase

45. Daughter cells

46. http://www.cellsalive.com/mitosis.htm http://www.sci.sdsu.edu/multimedia/mitosis /http://www.sci.sdsu.edu/multimedia/mitosis / http://highered.mcgraw- hill.com/sites/0072495855/student_view0/c hapter2/animation__how_the_cell_cycle_w orks.htmlhttp://highered.mcgraw- hill.com/sites/0072495855/student_view0/c hapter2/animation__how_the_cell_cycle_w orks.html