1. Now Showing at a science lab near you! Limited engagement
The Cell Cycle
Now Showing
at a science lab near you!
Limited engagement

2. Directed by the nucleus
A One Act Play
Directed by the nucleus
Produced by God

3. The Plot: one cell splits into two identical smaller cells.
Purpose:
1. increase size of an organism
2. replace damaged cells

4. Starring
DNA

5. The 3 faces of DNA Chromatin material – DNA as long strands
Sister chromatids – DNA coiled tightly and taking on the form of the letter X
Daughter chromosomes – Separated sister chromatids looking like the letter V

7. DNA (Deoxyribose nucleic acid)
Model discovered by Watson & Crick
Composed of 3 parts
Sugar (deoxyribose)
Phosphate
4 types of nucleotide bases
Adenine
Thymine
Guanine
Cytosine

9. Also starring
Centrioles
and
Spindle fibers

10. Overview of the Cell Cycle

11. Scene One
Interphase

12. Interphase The period of time between cellular divisions
Time period for normal cellular metabolism
Composed of 3 parts G1 S G2

13. G1 part of Interphase The first gap of Interphase
Time period before the DNA is replicated
Cell doubles in growth
Cytoplasmic organelles replicate
Time when the cell commits to cell division

14. S part of Interphase Time period of DNA replication
DNA unzips and new nucleotide bases are laid down beside the original nucleotide bases
Results in 2 identical DNA structures

15. G2 part of Interphase The second gap of Interphase Rapid cell growth
Time period for synthesis of enzymes and structures (asters & spindle fibers) necessary for cell division
Chromatin material checked for damage (repairs made if necessary)

16. 3 types of spindle fibers
Polar fibers – extend from centriole to centriole
Kinetochore fibers – extend from centriole to centromere on a chromosome
Asters – short fibers extending to the outside of the centrioles

17. Interphase Picture

18. One more review of the cell cycle

19. Mitosis Mitosis is part of the cell cycle, it is not the cell cycle
The following 4 scenes are the stages of mitosis

20. Scene Two
Prophase

21. Prophase
Chromatin material coils so the chromosomes look short, thick, and the shape of an X (now called sister chromatids)
Nuclear envelope begins to disintegrate

22. Prophase
Centrioles begin moving apart and towards opposite poles of the cell
Sister chromatids begin moving to the equator of the cell

23. Prophase Picture

24. Scene Three
Metaphase

25. Metaphase Easiest stage to recognize!
Kinetochore fibers pull sister chromatids so they are lined up at the equator of the cell

26. Metaphase Picture

27. Scene Four
Anaphase

28. Anaphase
Centromeres separate so the sister chromatids are no longer X’s but are now V’s (called daughter chromosomes)
Kinetochore fibers pull daughter chromosomes to a centriole
Centromeres travel ahead and the daughter chromosome arms travel behind (creating the V shape)

29. Anaphase Picture

30. Scene Five
Telophase

31. Telophase Daughter chromosomes arrive at the opposite poles
Daughter chromosomes unwind and are referred to as chromatin material again
Spindle fibers disintegrate
Nuclear envelope reforms around the chromatin material
Cytokinesis occurs

32. Cytokinesis Division of the cells’ cytoplasm
Different for animals and plants
Animals – cell membrane pinches in to form a cleavage furrow and divides the cell at the center
Plants – cell plate formed at equator of cell and cellulose is laid on each side to create new cell walls

33. Telophase Picture

34. Cytokinesis Picture

35. Cytokinesis Picture

36. One last look at the cell cycle

37. How well do you remember the stages of the cell cycle?