1. THE CELL CYCLE Chapter 10 Biology CPA

2. TheLifeCycleofCells

3. CELL GROWTH A cell is limited by its cell size The larger the cell the harder it is to move through tissue and get nutrients In order to stay alive and not grow continuously, the cell will divide

4. REASONS WHY TO DIVIDE DNA Genetic information stored Found in the nucleus of the cell DNA would not be able to keep up with demand of the cell Transport Rate decreases as the cell size increases Takes too long for nutrients and wastes to move in and out of cell

5. SURFACE AREA TO VOLUME Surface Area Area on outside of cell where reactions can occur As a cell increases, the surface area decreases

6. CELL DIVISION AND REPRODUCTION Asexual Reproduction Produces identical offspring from a single parent Used by many single-celled organisms Ex: bacteria Occurs very quickly Sexual Reproduction Produces genetically different offspring from two parents Fusion of two parent cells

7. CHROMOSOMES Made up of our DNA Holds genetic information Tight coils or rod like structures Organisms have a specific amount of chromosomes  Humans have 46 chromosomes of DNA in every somatic cell

8. CHROMOSOME STRUCTURE Histones are proteins that DNA wraps around to make the chromosome shape Chromosomes are made of two sister chromatids Identical to each other

9. CHROMOSOMES Centromeres are in the center of a chromosome Chromosomes are tightly coiled strings of DNA called chromatin Chromatin is the string-like form of DNA

10. CHROMOSOME NUMBERS There is a specific number of chromosomes in each organism Humans autosomes and sex chromosomes We have 2 sex chromosomes Either X or Y We also have 22 autosomes Which do not code for gender

11. KARYOTYPE A karyotype is a picture of one set of chromosomes Shows you sex of organism Shows your any chromosomal disorders

12. CHROMOSOME NUMBERS A diploid cell contains 2 sets of each chromosome Prefix di = 2 A haploid cell contains only 1 set of each chromosome Half of the total number Usually sex cells

13. CELL DIVISION IN PROKARYOTES Prokaryotes No nucleus No organelles Ex: Bacteria Reproduction is VERY fast Copy DNA Split into two cells Cell division is called binary fission

14. EUKARYOTIC CELL REPRODUCTION Eukaryotes Have a nucleus Have organelles Ex: Humans, plants Complex reproduction Everything needs to be controlled! Much longer process – about 18 hours!

15. CELL REPRODUCTION A cell splits to make 2 identical copies If asexual reproduction Only 1 cell involved This occurs in 3 main stages 1.Interphase – Growth 2.Mitosis – Splitting of the cell 3.Cytokinesis – Splitting of the cytoplasm

16. INTERPHASE Cell growth 90% of cell’s life is spent in interphase. 3 Part of Interphase: G 1, S, G 2

17. G 1 PHASE The cell is growing The organelles are doubling

18. S PHASE Takes place when cells are too big S = Synthesis of DNA DNA is replicated so there is a set for each new cell

19. DNA REPLICATES IN INTERPHASE SO THE DAUGHTER CELLS EXACT COPIES OF THE DNA

20. G 2 PHASE Cell growth again Replication of organelles Last stage of interphase Cell prepares for cell division

21. HOW IS DNA COPIED? Each cell has an protein called helicase Enzyme the unwinds the DNA making 2 identical strands http://www.youtube.com/watch?v=zdDkiRw1PdU

22. MITOSIS Cell Division

23. MITOSIS The part of a cell’s life cycle when the cell’s nucleus divides into 2 identical nuclei 4 steps: Prophase Metaphase Anaphase Telophase

24. PROPHASE All organelles disappear Centrioles separate and move to opposite pole Chromatin becomes chromosomes Centrioles shoot off spindle fibers

25. METAPHASE Chromosomes line up at the equator

26. ANAPHASE Centromere splits Sister chromatids attach to the short spindle fibers Spindle fibers shorten and bring the sister chromatids to opposite poles

27. TELOPHASE Chromatids become chromatin (one at each pole) Spindle disappears Organelles reappear

28. CYTOKINESIS Once mitosis has finished! Last stage of cell cycle Process is when the cytoplasm splits apart There are now 2 identical cells

29. CYTOKINESIS IN PLANT CELLS A cell plate forms between the two nuclei. The cytoplasm divides. A cell wall forms two daughter cells.

30. CYTOKINESIS IN ANIMAL CELLS Cell membrane pinches in at equator Cleavage furrow

31. MITOSIS: DIVISION OF THE NUCLEUS

32. CELLS IN VARIOUS STAGES OF THE CELL CYCLE

33. CONTROL OF CELL DIVISION Checkpoints (Regulatory Proteins) DNA repair enzymes will fix any mutations, if checkpoint is passed mitosis will occur Mitosis checkpoint – if all is correct, the 2 daughter cells will enter G1 phase and start over again If a cell does not meet requirements for checkpoints, the cell will be programmed to die  Apoptosis is controlled cell death

34. Uncontrolled Mitosis is cancer.

35. WHEN CONTROL IS LOST Enzyme proteins are not functioning properly causing cell to reproduce out of control Could cause cancer Cancer cells do not respond to body’s signals that control mechanisms

36. COMPARE/CONTRAST

37. HOW ELSE CAN OUR BODY CONTROL CANCER?