L7 - Cell Cycle

Question 1

what is the cell cycle?

Answer 1

The series of events that take place when a cell divides

It consists of periods of cell growth and then division (mitosis or meiosis)

Question 2

What are the 3 main stages?

Answer 2

Interphase - Cell prepares to divide

Nuclear division - Nucleus of cell divides

Cell division - Separation of cytoplasm to form daughter cells
(also called cytokinesis)

Question 3

What are the detailed phases?

6

Answer 3

G1 (first growth stage)

S (synthesis stage)

G2 (2nd growth stage)

M (mitosis)

Cytokinesis

G0

Question 4

what happens in the G1 phase?

Answer 4

rapid cell growth

proteins are synthesised for

manufacture of new organelles

lasts 10 hours

Question 5

what happens in the S phase?

Answer 5

DNA is replicated

lasts 9 hours

Question 6

what happens in the G2 phase?

Answer 6

organelles are duplicated, centrioles duplicate

Lasts 4 hours

Question 7

what happens in the M phase?

Answer 7

mitosis

Question 8

what happens in the cytokinesis phase?

Answer 8

Separation of cytoplasm to form daughter cells

Question 9

what happens in the G0 phase?

Answer 9

cells may differentiate, die or enter senescence (where they stop dividing)

Question 10

why does cell mass increase initially and then decrease?

Answer 10

increase - there is rapid cell growth

decrease - cytokinesis

Question 11

why does DNA mass increase just after the start,

then decrease just before 24 hours

and then stay constant for several hours before increasing again?

Answer 11

increase - DNA being replicated

decrease - mitosis takes place

constant - synthesising