1. The Cell Cycle, Mitosis, and Cancer
Glencoe Biology Chapter

2. The Cell Cycle: The “lifetime” of a cell
growth period= INTERPHASE
G1, S, G2
G1, G2: cell Grows
S: DNA Synthesis (duplicates)
INTERPHASE S
(DNA synthesis) G1
Mitosis G2
Cytokinesis
MITOTIC
(M) PHASE

3. The Cell Cycle NUCLEAR DIVISION = MITOSIS
the cell’s nucleus and genetic material DIVIDE.
Prophase, Metaphase, Anaphase, and Telophase (PMAT)
INTERPHASE S
(DNA synthesis) G1
Mitosis G2
Cytokinesis
MITOTIC
(M) PHASE

4. The Cell Cycle CYTOKINESIS: The cytoplasm divides, creating a new cell
M-PHASE: MITOSIS + CYTOKINESIS
INTERPHASE S
(DNA synthesis) G1
Mitosis G2
Cytokinesis
MITOTIC
(M) PHASE

5. So what does this have to do with cancer?
The cell cycle has 3 main checkpoints
If a cell receives a go-ahead signal at the G1 checkpoint, it will continue dividing
If the cell does not receive the go- ahead signal, it will exit the cycle and not divide
Tumors form due to out of control cell division
cancer cells video
discovery of cell cycle video
G1 checkpoint
Control
system S G1 M G2
M checkpoint
G2 checkpoint

6. What causes cancer?
Cancer is caused by mutations, which creates abnormal cell growth.
A mutation is a change to an organism’s genetic material. In our case, DNA.
CARCINOGENS: Agents that cause cancer.
Radiation
UV radiation
X rays
Chemicals
Alcohol
Tobacco
Drugs
Infectious agents
Viruses like HPV
What causes mutations?(changes our DNA?) Agents of Mutations = “MUTAGENS”:

7. Genetic Material names:
Chromatin:
Chromatin = DNA that is long and tangled
Chromatin coils up (during M phase) to form
chromosomes
CHROMOSOME
CHROMATID
CENTROMERE
duplicated, coiled DNA, = chromosome

8. VOCABULARY ! Human chromosome number:
46 in body cells (diploid OR 2N)
23 in sex cells (haploid OR N)
A picture of species’ full set of chromosomes is a KARYOTYPE

9. Why do cells need to divide?
unicellular organisms: Asexual REPRODUCTION (only needs one parent; no genetic variation; mitosis)
Multicellular organisms depend on cell division for:
Growth
Repair
2 Types of cell division:
MITOSIS: MAKES SOMATIC/BODY CELLS/unicellular organisms (creates GENETICALLY IDENTICAL cells)
MEIOSIS: MAKES SEX CELLS (GENETICALLY DIFFERENT CELLS). Sexual organisms. Creates genetic variation

10. INTERPHASE – BEFORE MITOSIS

11. 1st stage of Mitosis: Prophase
Chromatin coils up into visible chromosomes
nucleus disappears
Centrioles begins to separate

12. 2nd Stage of Mitosis: Metaphase
Spindle fibers pull the chromosomes to the middle (equator/metaphase plate) of the cell

13. 3rd stage of Mitosis: Anaphase
During Anaphase…
Chromosomes are pulled apart forming chromatids.
chromatids move towards opposite sides of the cell.

14. 4th stage of Mitosis: Telophase
chromatids uncoil, becoming chromatin
nuclear envelope reforms
Mitosis is COMPLETE!!!

15. Cytokinesis: last stage in the cell cycle
cytoplasm divides into 2 new cells
ANIMAL CELLS: The cell membrane will move inward and pinch apart
PLANT CELLS: A new cell wall forms between the two new cells (CELL PLATE)

16. SUMMARY - MITOSIS Number of ROUNDS of cell divisions: 1
Number of daughter cells :
Genetically identical? Yes
Chromosome #: Same as parent
Where: Somatic cells (non-sex cells)
When: Throughout life
Role: Growth and repair