1. TheLifeCycleofCells

2. 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

3. 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

4. Surface Area to Volume Surface Area –Area on outside of cell where reactions can occur –As a cell increases, the surface area decreases

5. 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

6. 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

7. 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

8. 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

9. Karyotype A karyotype is a lab picture of one set of chromosomes

10. Diploid/Haploid 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

11. 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

12. 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!

13. 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

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

15. G 1 Phase The cell is growing The organelles are doubling

16. 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

17. DNA replicates in Interphase so the daughter cells exact copies of the DNA

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

19. cell is not dividing cell is growing, performing respiration, producing, photosynthesizing, doing whatever functions it is supposed to do At some point, the cell can’t diffuse fast enough and that signals the end of interphase At the very end of interphase, the chromatin makes an exact copy of itself in a process called DNA replication.

20. 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=zdDkiRw1P dUhttp://www.youtube.com/watch?v=zdDkiRw1P dU

21. Mitosis The part of a cell’s life cycle when the cell divides it nuclear contents into 2 nuclei which are identical Mitosis consists of 4 steps: Prophase Metaphase Anaphase Telophase

22. all sub-cellular organelles disappear centrioles separate and move to opposite poles chromatin become chromosomes centrioles shoot off spindle fibers (short and long)

23. chromosomes line up at the equator

24. centromere splits sister chromatids attach to the short spindle fibers short spindle fibers shorten and bring the sister chromatids to opposite poles.

25. chromatids become chromatin (one at each pole) spindle disappears subcellular organelles reappear

26. Cytokinesis Once mitosis has finished! Last stage of cellular reproduction This process is when the cytoplasm splits apart There are now 2 identical cells

27. Cytokinesis in Plant Cells Cell plate forms at equator and grows out to the cell wall Cell plate

28. Cytokinesis in Animal Cells Cell membrane pinches in at equator Cleavage furrow

44. Control of Cell Division G1 Checkpoint –Enzymes will kick in if cell is large enough and conditions are favorable to reproduce G2 Checkpoint –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

45. Uncontrolled Mitosis is cancer.

46. 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

47. Some Cancer Statistics: 1 in 7 people will have some form of cancer in their lifetimes. 1 in 8 women will get breast cancer. Lung cancer is the leading cause of cancer deaths in the U.S. There are approx. ½ million deaths from cancer in the U.S. per year.

48. Compare/Contrast

49. How else can our body control cancer?