1. Mr. Fuchigami Wednesday, April 11th, 2018
THE CELL CYCLE
Mr. Fuchigami
Wednesday, April 11th, 2018

2. Review: Unicellular vs. Multicellular Organisms

3. What is the cell cycle?
A repeating series of events that occur as a cell grows and divides.
Cells need to make new copies of themselves in order to:
Grow and replace damaged or dead cells (multicellular organisms).
Form a new unicellular organism.

4. Cell Cycle Rates
FAST: Cells are constantly dividing throughout their lifespan.
SLOW: Cells very rarely or never divide.
Examples:
-Fast: skin cell, nail cell, hair follicle cell
-Slow: brain cell, eye cell
Skin cell
Brain cell

5. 2 Main Phases of Cell Cycle
Interphase: Cell grows and duplicates its DNA to prepare for cell division. DNA exists in the form of chromatin. Mitosis & Cytokinesis: Cell divides to produce 2 identical cells called daughter cells. DNA exists in the form of chromosomes.

6. Different Steps of the Cell Cycle
G1 (Gap 1):
Cell grows in size.
Cell organelles (excluding the DNA) are duplicated.
S (Synthesis):
Each of the 46 chromosomes are duplicated = DNA synthesis.

7. Different Steps of the Cell Cycle
G2 (Gap 2):
Cell continues to grow and prepares for cell division.
M (Mitosis):
Nuclear division. Genetic material is separated equally into 2.
Cytokinesis:
Cell divides the cytoplasm and organelles to produce 2 identical daughter cells.

8. Cell Cycle - Overview

9. Cell Cycle Checkpoints
Specific points during the cell cycle where we check for mistakes in or damages to the cell and/or DNA.
The cell cycle must be stopped so that the cell can be repaired or killed.

10. Different Cell Cycle Checkpoints
G1 checkpoint:
Check the cells for DNA damage. Cell must grow to an appropriate size and have enough energy to prepare for cell division.
G2 checkpoint:
Check to make sure DNA has been correctly duplicated. There should be no damages or mistakes.
M checkpoint:
Check to make sure chromosomes will be separated into two cells equally.
*Indicate on the diagram of the handout.

11. Textbook Terms Please read pages 105-107 and define the bolded terms:
Chromosome
Chromatin
Gene
Somatic cell
Mitosis
Sister chromatid
Centromere
Spindle fibres