1. Cell Cycle

2. Cell Reproduction When a cell divides in two cells
Cells need to grow larger because there is a limit to cell size
Needed to replace dead cells
Composed to MITOSIS and CYTOKINESIS

3. Chromosome Replication
Chromosomes are uncoiled and duplicated
CHROMATIDS are the two identical strands of a duplicated chromosome joined at the centromere

4. Cell Cycle Interphase Rest/growth phase Cell grows bigger
Chromosomes are uncoiled and duplicated

5. Cell Cycle Prophase Preparing for mitosis
Chromosomes begin to coil And condense into visible threads
Centrioles move to the opposite ends of the cell
The spindle fibers form between the centriole pairs
Nuclear membrane breaks down and disappears

6. Cell Cycle Metaphase Middle stage of mitosis
Paired chromatids begin to move towards the center of the cell between the two centrioles

7. Cell Cycle Anaphase Leaving stage of mitosis
Each pair of chromatids splits at the centromere and becomes a single chromosome so there are TWICE as many chromosomes
Chromatids move to opposite ends of the cell

8. Cell Cycle Telophase The last stage
Nuclear membranes form around the two new sets of chromosomes
Spindle disappears
Chromosomes begin to uncoil and gradually become less visible
Now two nuclei in the cell

9. Cell Cycle Cytokinesis “Dividing materials
Division of organelles and the other substances in the cytoplasm into roughly equal halves
In animal cells, an indent forms in the cell membrane and deepens until the cell is pinched into half
In plant cells, a cell plate enlarges until it reaches the outer surface splitting the cell in half

10. Diploid = (2n) There are double the number of chromosomes
Example: human body cells have 46 chromosomes
Haploid = (1n) There are half the number of chromosomes in the cells
Example: human sperm and egg cells have 23 chromosomes

11. In mitosis the number of chromosomes are the same from cell to cell
In meiosis the number of chromosomes are halved
When fertilization occurs… the chromosome numbers double to form body cells

12. Meiosis
For the production of gametes
Interphase
chromosomes duplicate

13. Meiosis Prophase I Metaphase I - Chromosomes coil and become visible
- Nuclear membrane disappears (crossing over may occur)
Spindle forms
Metaphase I
- Chromosomes move to the middle and line up beside each other (crossing over may occur)

14. Meiosis Anaphase I Telophase I Cytokinesis Chromosomes move apart
Paired chomosomes uncoil
Nuclear membrane forms
Spindle disappears
Cytokinesis
- TWO CELLS

16. Meiosis 7. Prophase II Paired chromatids coil Spindle forms
Nuclear membrane disappears
Metaphase II
Chromosomes line up in the middle of the cell
9. Anaphase II
- each chromosome splits
- move to the opposite ends of the cell

17. MEIOSIS Telophase II - chromosomes uncoil - nuclear membrane form
Cytokinesis
- Total of 4 cells from one cell

19. QUIZ QUIZ 2