Cell Division - Mitosis

Question 1

Interphase

Answer 1

• Cell growth and DNA replication take place.

- Organelles are replicated and ATP content increased for cell division

Question 2

Prophase

Answer 2

Chromosomes condense
Centrioles move to opposite ends of the cell forming spindle
Nuclear envelope breaks down
Chromosomes are free in cytoplasm

Question 3

Metaphase

Answer 3

Chromosomes (two chromatids) line up along cell equator

Attached to spindle by centromere

Question 4

Anaphase

Answer 4

Centromeres divide
Sister chromatids separate
Spindle contracts
Chromatids pulled via centromere to opposite poles

Question 5

Telophase

Answer 5

Chromatids reach opposite poles
Uncoil and become long thin chromosomes
Nuclear envelope forms around each chromosome group (two nuclei)
CYTOKINESIS

Question 6

Cytokinesis

Answer 6

Cell membrane pinches and cytoplasm divides forming two identical daughter cells.
Interphase begins again

Question 7

Mitosis

Answer 7

Growth and repair. Some cells take longer to complete cell cycle than others.

Question 8

Cancer

Answer 8

Cell Cycle controlled by genes
Mutation in genes can cause cells to grow out of control
Keep on dividing = tumours
cancer = tumour that invades surrounding tissue

Question 9

Cancer treatments

Answer 9

Some treatments are designed to control the rate of cell division by disrupting the cell cycle.
Treatments only target cells dividing more frequently (normal and tumour - why hair falls out during chemo)

Question 10

Cancer treatment examples

Answer 10

Chemotherapy - prevent enzyme synthesis required for DNA replication so S phase can’t be entered so cell kills itself
Radiation and other drugs damage DNA. During cell cycle, DNA in the cell is checked for sever damage - if present, cell kills itself.