1.5b The Cell Cycle

Question 1

What does the cell cycle consist of?

Answer 1

• Interphase
• Mitotic (M) Phase

Question 2

What sections do interphase involve?

Answer 2

Growth and DNA synthesis:
- G1 -> a growth phase
- S Phase -> during which the DNA s replicated
- G2 -> a further growth phase

Question 3

What are the 2 stages in the mitotic phase?

Answer 3

• mitosis
  -cytokinesis

Question 4

What is a more detailed version of what happens in the mitotic phase?

Answer 4

• In mitosis the chromosomal material is separated by the spindle microtubules.
• Followed by cytokenisis, in which the cytoplasm is separated into two daughter cells

Question 5

What are the 4 stages of mitosis?

Answer 5

• Prophase
• Metaphase
• Anaphase
• Telophase

Question 6

What happens in prophase?

Answer 6

• DNA condenses into chromosomes each consisting of two chromatids
• nuclear membrane breaks down
• Spindle microtubules extend from the MTOC by polymerisation and attach to chromosomes via their kinetochores in the centromere region

Question 7

What happens in metaphase?

Answer 7

Chromosomes are aligned at the metaphase plate (equator of the spindle)

Question 8

What happens at anaphase?

Answer 8

• As spindle microtubules shorten by depolymerisation, sister chromatids are separated

-The chromosomes are pulled to opposite poles

Question 9

What happens in telophase?

Answer 9

• The chromosomes decondense and nuclear membranes are formed around them