1. Cell Cycle  Stages in growth & division  G1 Phase  S Phase  G2 Phase  M Phase  Cytokinesis copyright cmassengale

2. G1 Phase  First growth stage  Cell increases in size  Cell prepares to copy its DNA copyright cmassengale

3. Synthesis Phase  Copying of all of DNA’s instructions  Chromosomes duplicated copyright cmassengale

4. G2 Phase  Time between DNA synthesis & mitosis  Cell continues growing  Needed proteins produced copyright cmassengale

5. M Phase  Cell growth & protein production stop  Cell’s energy used to make 2 daughter cells  Called mitosis or karyokinesis (nuclear division) copyright cmassengale

6. Life Cycle of a Cell Mitosis is a cycle with no beginning or end. copyright cmassengale

7. Interphase – Resting Stage  Cells carrying on normal activities  Chromosomes aren’t visible  Cell metabolism is occurring  Occurs before mitosis copyright cmassengale

8. Interphase

9. Stages of Mitosis  Prophase  Metaphase  Anaphase  Telophase copyright cmassengale

10. Cells Undergoing Mitosis copyright cmassengale

11. Steps in Prophase  DNA coils tightly & becomes visible as chromosomes  Nuclear membrane disappears  Nuceolus disappears  Centrioles migrate to poles  Spindle begins to form copyright cmassengale

12. Prophase

13. Eukaryotic Chromosome copyright cmassengale

14. Human Chromosomes copyright cmassengale

15. Steps in Metaphase  Spindle fibers from centrioles attach to each chromosome  Cell preparing to separate its chromosomes  Cell aligns its chromosomes in the middle of the cell copyright cmassengale

16. Metaphase

17. Steps in Anaphase  Cell chromosomes are separated  Spindle fibers shorten so chromosomes pulled to ends of cell copyright cmassengale

18. Mitotic Spindle copyright cmassengale

19. Anaphase

20. Steps in Telophase  Separation of chromosomes completed  Cell Plate forms (plants)  Cleavage furrow forms(animals)  Nucleus & nucleolus reform  Chromosomes uncoil copyright cmassengale

21. Telophase Plant Animal copyright cmassengale

22. Cytokinesis  Occurs after chromosomes separate  Forms two, identical daughter cells copyright cmassengale

23. Cytokinesis Cell Plate Forming in Plant Cells copyright cmassengale

24. Chromosomes & Karyotypes 24copyright cmassengale

25. Chromosomes 25copyright cmassengale

26. Chromosome Number All cells in the human body (SOMATIC CELLS) have 46 or 23 pairs of chromosomes Called the DIPLOID or 2n number GAMETES (eggs & sperm) have only 23 chromosomes Called the MONOPLOID or 1n number 26copyright cmassengale

27. Nondisjunction Chromosomes may fail to separate during meiosis Resulting gametes may have too few or too many chromosomes Disorders: – Down Syndrome – three 21 st chromosomes – Turner Syndrome – single X chromosome – Klinefelter’s Syndrome – XXY chromosomes 27copyright cmassengale

28. Normal Male 28 2n = 46 copyright cmassengale

29. Normal Female 29 2n = 46 copyright cmassengale

30. Male, Trisomy 21 (Down’s) 30 2n = 47 copyright cmassengale

31. Female Down’s Syndrome 31 2n = 47 copyright cmassengale

32. Klinefelter’s Syndrome 32 2n = 47 copyright cmassengale

33. Turner’s Syndrome 33 2n = 45 copyright cmassengale