1. Cell Division

2. The Cell Cycle Every hour, about one billion (109) cells die and one billion cells are made in your body

3. The Cell Cycle Through careful observation, scientists have identified a repeating cycle of events in the life of a cell This cycle of events is called the cell cycle

4. The Cell Cycle

5. The Cell Cycle The cell cycle has four phases: G1 Phase – Cell growth S Phase – DNA Replication G2 Phase – Preparation for Mitosis M Phase – Mitosis Interphase

6. Chromosomes Every cell contains chromosomes Chromosomes are long pieces of coiled DNA and proteins

7. Chromosomes Chromosomes are only visible when the cell is dividing. When the cell is not dividing, the DNA and proteins are spread throughout the cell as chromatin

8. Chromosomes At the beginning of cell division, the chromosomes condense into visible structures Dude, mitosis starts in five minutes… I can’t believe you’re not condensed yet!

9. Chromosomes

10. Chromosomes Before cell division can occur, each chromosome is copied so that each chromosome consists of two identical sister chromatids When cells divide, one chromatid goes to each of the new cells

12. G1 Phase – Cell growth

13. S Phase – DNA Replication

14. G2 Phase – Preparation for Mitosis

15. M Phase – MitosisInterphase

16. Interphase During interphase, the cell takes in nutrients, grows and conducts other normal cell functions

17. First Growth Phase (G1) The G1 Phase is a period of growth for the cell During this phase, new proteins and organelles are produced

18. Synthesis Phase (S) During the S Phase, the cell makes (synthesizes) an entire copy of the DNA of the cell

19. Second Growth Phase (G2) During the G2 Phase, the cell produces the organelles and structures needed for cell division The G2 Phase is the shortest part of interphase

20. Cell Division Once the cell is ready to divide and make two new identical cells, it enters mitosis (M Phase) During the M Phase, all of the cell’s energy is devoted to the process of cell division

21. Mitosis There are four phases in mitosis: Prophase Metaphase Anaphase Telophase(and Cytokinesis)

22. Mitosis At the end of telophase, two daughter cells are formed, each containing identical genetic information

23. Prophase During prophase, the chromatin (DNA and proteins) that makes up the chromosomes condenses The DNA has already been replicated, so the chromosomes contain two identical sister chromatids

24. Metaphase During metaphase, the chromosomes line up at the center of the cell Spindle fibers extend from the poles of the cell and attach to the centromeres of each chromosome

25. Anaphase During anaphase, the sister chromatids separate at the centromere The separated chromosomes are pulled to opposite ends of the cell

26. Telophase & Cytokinesis During telophase, the cell divides the cytoplasm into two portions The process of splitting the cytoplasm is known as cytokinesis

27. Telophase & Cytokinesis

28. Telophase & Cytokinesis

29. Telophase & Cytokinesis

30. Interphase

31. Cell Death The cell cycle regulates how long a cell lives Sometimes cells die because they have suffered injury or damage that cannot be repaired

32. Apoptosis A cell also dies when it is no longer needed or useful to the organism This regulated or controlled cell death is called apoptosis The cell on the bottom is healthy and normal, while cell on the top is undergoing apoptosis.