1. To reproduce or not to reproduce, that is the question. The cell cycle

2. Cells must either reproduce or they die. Cells that can not reproduce and are destined to die are terminal cells (red blood, nerve cells, muscles cells etc.). The "life of a cell" is termed the cell cycle as there are distinct phases. Once a cell comes into existence it is in the G1 or Gap 1 (called Growth 1). During this time organelles are reproducing, protein

4. synthesis is occurring for growth and differentiation. Because, transcription is occurring, the DNA is uncoiled. This phase is the most variable, ranging from almost nothing to years. The average may be 10 hrs. Some cells are stuck in G1 or called G0 and they never replicate. Ex. nerve and muscle cells

5. Cells must either reproduce or they die (terminal cells) like red blood cells, muscle cells and nerve cells. The cell cycle is the "life of a cell" and has distinct phases. The first phase is G1 or Gap 1 (called Growth 1). This is when organelles are reproducing, protein synthesis is occurring for growth and differentiation. Transcription is occurring, the DNA is uncoiled. G1 is the most variable, ranging from almost nothing to years. The average may be 10 hrs. Terminal cells stay in G1 or called G0 and they never replicate.

6. S or synthesis is the time that DNA is being replicated. There is some organelle replication as well. This phase ensures that each emerging daughter cell will have the same genetic content as the mother cell.

7. S or synthesis is the time that DNA is being replicated. There is some organelle replication. Each new daughter cell will have the same genetic content as the mother cell and each other.

8. G2 or Gap 2 (Growth 2)is the time from the end of S until the onset of mitosis. During this time, the cell is preparing for mitosis. Proteins are being made and organized for mitosis. A high increase in tublin for microtubules for spindle fibers.

10. Mitosis or cell division, is the period of time that the nucleus and cyctoplasm replicates and divides to produce two genetically identical daughter cells. The phases are triggered by the accumulation of control substances called trigger proteins. These proteins only work when they have a phosphate attached to them. Kinases are molecules that put the phosphates on the trigger proteins. Cyclins are molecules that activate the kinases.

11. Mitosis or cell division, is the period of time that the nucleus and cyctoplasm replicates and divides to produce two genetically identical daughter cells. The phases are triggered by the accumulation of chemical signals called trigger proteins. These proteins only work when they have a phosphate attached to them. Kinases are molecules that put the phosphates on the trigger proteins. Cyclins are molecules that activate the kinases.

12. The cell division kinase, cdk, has the ability to activate either a chemical messengers( & ) for either DNA replication or mitosis by adding a phosphate to them. The kinases are activated by molecules called cyclins. M-cyclin for mitosis and the S-cyclin for DNA synthesis

13. The cell divison cycle kinase can be found in several forms – normal mitosis promoting form DNA synthesis promoting form There are also chemical messengers that must be phosphorylated once attached to the cell division cycle kinase-mitosis, DNA synthesis

14. 1.In G1 and G2 cyclins are made that activate kinases 2.Kinases phosphorylate many chemical signals which trigger S and M phases to start 3.Cyclins are destroyed and kinases go back to inactive form. 4.The concentration cyclins vary which determine the activity of kinases. The level of kinases remain stable

16. This graph represents the amount of DNA found in the cell during the cell cycle A –G1 B- S C- G2 D- Mitosis

17. This graph represents the amount of DNA found in the cell during the cell cycle A –G1 B- S C- G2 D- Mitosis