2.6.1 The Cell Cycle

Question 1

what is the cell cycle?

Question 2

what are the three phases of the cell cycle?

Answer 2

-interphase
-nuclear division (mitosis)
-cell division (cytokinesis)

Question 3

what is the movement from one phase to another triggered by?

Answer 3

chemical signals called cyclins

Question 4

what are cyclins?

Answer 4

chemical signals that trigger the movement from one phase to another

Question 5

what is the length of the cell cycle dependent on?

Answer 5

-environmental conditions
-the cell type
-the organism

Question 6

what is the order of the cell cycle?

Answer 6

Interphase -G0, S and G1
Mitosis
Cytokinesis

Question 7

what happens in Interphase? overview

Answer 7

the cell increases in mass and size and carries out its normal cellular functions

Question 8

what are the three phases of interphase?

Answer 8

G1 phase
S phase
G2 phase

Question 9

what happens in G1of interphase?

Answer 9

the cell makes the RNA, enzymes and other proteins required for growth during the G1 phase and cell grows

Question 10

what is G0 of interphase?

Answer 10

it is a resting phase, that is not found in all cells

Question 11

what are gap phases essential for?

Answer 11

growth and regulation

Question 12

what does G stand for?

Answer 12

growth

Question 13

what happens in S of interphase?

Answer 13

the DNA in the nucleus replicates

Question 14

what is the result of S of interphase?

Answer 14

results in each chromosome consisting of two identical sister chromatids

Question 15

when does the cell receive a signal instructing it to divide again?

Answer 15

at some point in G1 phase

Question 16

what happens in G2 of interphase?

Answer 16

the cell keeps growing and the production of tubulin protein, which is used to make microtubules for the mitotic spindle

Question 17

where are the two main checkpoints?

Answer 17

G1 and G2

Question 18

what does the checkpoint at G1 check for?

Answer 18

-cell size
-nutrients
-growth factors
-DNA damage
NOT DNA REPLICATION (hasn’t been replicated yet)

Question 19

what does the S stand for?

Answer 19

synthesis

Question 20

what does the G2 checkpoint check for?

Answer 20

-cell size
-DNA replication
-DNA damage
NOT GROWTH FACTORS NO CHECKING FOR NUTRIENTS

Question 21

what are the checkpoints function?

Answer 21

-prevent uncontrolled growth and division (could lead to cancerous tumours)
-detect and repair damage to DNA (eg by UV light)
-prevent reversal of the cell cycle
-check DNA is only replicated once (could cause Down Syndrome)