Cell Cycle and Regulation

1. Cell Cycle and Regulation Section 5.1 and 5.3

2. KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions.

3. The cell cycle has four main stages. • The cell cycle is a regular pattern of growth, DNA replication, and cell division.

4. Gap 1 (G1): cell growth and normal functions • The main stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis. • DNA synthesis (S): copies DNA • Gap 2 (G2): additional growth • Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis) • Mitosis occurs only if the cell is large enough and the DNA undamaged.

5. Cell Cycle Checkpoints • G1 checkpoint: is the most significant because the cell is committed to divide once it passes this checkpoint • If the cell does not pass this checkpoint, • It could enter G0 where it continues to perform its normal functions but does not divide • Death by apoptosis (programmed death) • G2 checkpoint: the cell verifies that DNA has replicated and mitosis can proceed • M checkpoint: pauses between metaphase and anaphase to allow the proper attachment of chromosomes to spindle fibers; ensures that the chromosomes will be distributed accurately to the daughter cells

6. Cell Cycle Checkpoints

7. webbed fingers • Apoptosis is programmed cell death. • a normal feature of healthy organisms • caused by a cell’s production of self-destructive enzymes • occurs indevelopmentof infants

8. normal cell cancer cell bloodstream Cell division is uncontrolled in cancer. • Cancer cells form disorganized clumps called tumors. • Benign tumors remain clustered and can be removed. • Malignant tumors metastasize, or break away, and can form more tumors.

9. Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation. • Cancer cells do not carry out necessary functions.

10. Carcinogens are substances known to promote cancer. • Standard cancer treatments typically kill both cancerous and healthy cells.