1. Making copies of your cells...
Cell Reproduction
Making copies of your cells...

2. Chromosomes bodies of DNA and protein
the DNA strand is tightly coiled around a chunk of protein
if straightened out, the DNA strand would be 5 cm (2 in.) long
each contains 2 “sister” chromatids joined by a centromere

3. Chromosomes

4. The Cell Cycle Sequence of growth and division
Consists of two major phases:
Interphase and Mitosis
Cells spend most of their time in Interphase (about 95% of the time)
Mitosis has four phases:
Prophase, Metaphase, Anaphase, and Telophase

5. The Cell Cycle Interphase:
DNA is copied and centrioles duplicate in preparation for mitosis
time of rapid growth and metabolic activity

6. Mitosis: The phases Prophase: (first and longest)
nucleus and nucleolus disappear, centrioles migrate to opposite ends of cell
spindle fibers form

7. Mitosis: The phases Metaphase: (shortest)
spindle fibers attach to centromeres
chromosomes line up on the equator

8. Mitosis: The phases Anaphase:
centromeres split and chromosomes are pulled apart
each chromatid is now a separate chromosome

9. Mitosis: The phases Telophase: (last)
cytokinesis occurs (cytoplasm pinches cell in half)
chromosomes unwind, spindle breaks down, nucleus and nucleolus reform

10. Control of the cell cycle
Even with 25 years of research, this is not fully understood
What we know:
enzymes monitor the cell’s progress from phase to phase
if enzymes are produced at the wrong time or they are overproduced then they will cause uncontrolled dividing of cells= Cancer
contact inhibition (or when the cells touch) will cause cells to stop growing unless the cells are cancerous

11. Cancer: what we know...
Currently it is believed that cancer is caused by changes in the genes that control cell cycle enzymes
Cancer cause tumors which deprive normal cells of the nutrients they need
Eventually cancer cells invade the circulatory system and destroy major organs

12. Cancer: what we know...
We think that cancer can be caused by either or both environmental and genetic factors
Examples of environmental factors: UV radiation, cigarette smoke, air pollution, water pollution, and even viruses