1. Cell Cycle

2. I. Cell Cycle The cell cycle is a series of events in eukaryotic cells that leads up to cell division. Cells grow, duplicate, and divide.

3. 4 Stages 1. Gap 1 (G 1 ) 2. Synthesis (S) 3. Gap 2 (G 2 ) 4. Mitosis (M)

4. 2 Processes The Cell Cycle occurs in two processes: 1. Interphase- G 1, S, G 2 2. Mitosis- Mitosis and Cytokinesis

5. Interphase G 1 - cell carries out normal functions. Cell has proteins to “check” the cell and make sure it is ready for synthesis. Organelles increase in number. S- cell copies its DNA. G 2 - cell carries out normal functions and grows. The cell has checkpoint proteins to check that the DNA is undamaged and the cell is the right size.

6. Mitosis M- nuclear membrane dissolves, DNA condenses to form chromosomes, two new nuclei form. Cytokinesis- process that divides the cell into two new daughter cells. Parent cells and daughter cells are identical!

7. Cell Cycle

8. Cells are Controlled Surface area to volume ratio in cell means that as a cell increases in size, the volume increases faster than the surface area. Contact Inhibition- cell growth is ceases when two cells come in contact with one another.

9. Cells are Controlled (cont.) Growth must be controlled and organized. If cell division becomes uncontrollable, cancer occurs. Tumor- is an organized clump of uncontrollably dividing cells.

10. II. Mitosis and Cytokinesis Chromosome- is a long strand of DNA that forms an “X” shape. 46 chromosomes are in the human body.

11. DNA During Interphase DNA wraps around Histone Proteins. These proteins make DNA condense. During interphase, DNA forms chromatin. Chromatin- is the “loose” combination of DNA and protein. “Loose” refers to how DNA folds in on itself.

12. DNA at the Beginning Mitosis DNA tightly condenses into the characteristic “X.” This is very visible under a microscope. Chromatid refers to one of the sides. The sides are identical. Centromere is an area of condensed chromosome that holds the chromatids together. Gene- segment of a chromosome that codes for a specific protein.

14. Phases of Mitosis

15. Prophase Chromatin condenses into tight chromosomes. Nuclear membranes disappear. Centrosomes go to opposite ends of the cell and spindle fibers form.

16. Metaphase Spindle fibers attach to the centromere on each chromosomes. Chromosomes align on the cell’s equator

17. Anaphase Spindle fibers shorten and pull the chromatids away from one another. Sister chromatids separate from each other into daughter chromatids. Chromatids go to opposite ends (poles) of the cell.

18. Telophase Complete set of chromosomes are at each end (poles) of the cell. Nuclear membrane starts to form.

19. Cytokinesis Cell divides into two identical daughter cells. Cell Cycle is complete. In animal cells, a furrow or trench is formed. The membrane gradually pinches closed. In Plant cells, a cell plate is formed between the two nuclei and a cell wall is formed from cellulose.

20. Animal vs. Plants

21. III. Reproduction Two Types: 1. Asexual- the creation of genetically identical offspring from a single parent by mitosis. Ex. Binary Fission- asexual reproduction by a single celled organism. The cell divides into two identical parts. 2. Sexual- fusion of two gametes that creates an offspring that is a genetic mixture of both parents by meioses.

22. Specialized Cells Somatic Cells- are body cells. They make up most of the body tissues and organs. Germ Cells- are cells in the reproductive organs. – Gametes- are the sex cells. – Ex: Sperm and ova (eggs)

23. Chromosomes Cells have 46 chromosomes or 23 pairs (one from the mother and one from the father). Homologous Chromosomes- refers to the pairs of chromosomes. 22 of the chromosomes are autosomes- chromosomes that define characteristics. 1 sex chromosome that controls the development of sexual characteristics.

24. Sex Chromosomes Humans have two different sex chromosomes: – X and Y Females are XX Males are XY

25. Meiosis Meiosis- is when the cells divide and the chromosome number cuts in half. Sex cells go from Diploid Cells (46 chromosomes) to Haploid Cells (23). Diploid also known as 2n and haploid known as 1n. N= chromosomes and # = chromosome amount

26. Meiosis I 1. Prophase I- nuclear membrane breaks down, the centrosomes move to opposite poles, and the chromosomes condense into pairs. 2. Metaphase 1- the pairs of chromosomes line up along the midline of the cell. 3. Anaphase 1- pairs of chromosomes move to opposite poles. 4. Telophase 1- the nuclear membrane can reforms and the cell starts to divide. 5. Cytokinesis- two new daughter cells form

27. Meiosis I

28. Meiosis II 6. Prophase II- The nuclear membrane breaks down, centrosomes move to opposite poles, and spindle fibers form. 7. Metaphase II- 23 chromosomes align along the equator. 8. Anaphase II- sister chromatids are pulled apart from each other and move to opposite poles. 9. Telophase II- nuclear membranes form around each set of chromosomes. 10. Cytokinesis- nuclear membranes form around the chromosomes at the poles.

29. Meiosis II

30. Outcomes Cells went from DIPLOID to HAPLOID. Diploid (2n)- cell has two copies of each chromosome. One from mother and one from father. This refers to the 46 Chromosomes. Haploid (1n)- cell only has one copy of each chromosome. – Now there are 23 chromosomes in the cell. – 22 are autosomes and 1 is a sex chromosome.

31. Mature Sex Cells Gamete- are mature sex cells. Ex: sperm and egg Gametogenesis- is the production of gametes. Sperm- male gamete Egg- female gamete

32. Difference Between Sperm and Egg

33. Sperm and Egg Sperm production = 4 sperm Egg Production = 1 Egg + 3 Polar Bodies Polar Bodies- are cells that are mainly DNA. The polar bodies cannot survive and are broken down. Once fertilized, the sperm and egg form a diploid cell (2n).

34. Crossing Over During Meiosis Crossing over recombines genes and causes genetic variation. Crossing Over- is the exchange of chromosome segments between homologous chromosomes during prophase I of Meiosis I. Chromosomes are very close together. A segment of chromatin breaks off and reattaches to another chromosome.

35. Crossing Over

36. QR Mitosis Activity Pictures Use the following slides to make up the QR Mitosis Activity.

37. Station 3

38. Station 5

39. Station 1

40. Station 2

41. Station 4

42. Station 6 http://www.youtube.com/watch?v=IeUANxFV XKc