Unit 1: Cell Cycle

Question 1

What are the two phases in the cell cycle called?

Answer 1

Interphase and M phase (mitosis and cytokinesis)

Question 2

what are the five steps in Mitosis

Answer 2

Prophase, prometaphase metaphase, anaphase and telophase

Question 3

what is the M phase controlled by

Answer 3

cytoskeleton

Question 4

what is the order of the cell cycle

Answer 4

G1, S, G2, M, cytokinesis

Question 5

what is the G1 stage?

Answer 5

the first growth stage where the cell makes new proteins and copies organelles

Question 6

what is the S phase?

Answer 6

when DNA replication occurs

Question 7

what is the G2 stage?

Answer 7

second growth stag, more proteins made and copies of organelles for preparation for mitosis

Question 8

what is interphase?

Answer 8

active period of growth and metabolism

Question 9

what is prophase?

Answer 9

chromosomes condense and become visible

mitotic spindle assembles between centromeres which have been replicated and have moved to opposite poles

Question 10

what is prometaphase?

Answer 10

the nuclear membrane breaks down
chromosomes attach to spindle microtubules via structures known as kinetochores (centromeres)
chromosomes start to actively move

Question 11

what is metaphase?

Answer 11

chromosomes line up along the equator of the cell by spindle fibres
spindle microtubules from each pole attach to the kinetochore of each chromosome
spindle fibre from one pole attaches to one chromatid of each chromosome and a spindle fibre from opposite pole attaches to the other chromatid

Question 12

what is anaphase?

Answer 12

contraction of spindle fibres cause the centromere of the chromosomes to separate and chromosomes are pulled to opposite ends of the cell

Question 13

what is telophase?

Answer 13

the chromosomes uncoil and lose visibility and the nuclear envelope toms around each set of chromosomes

Question 14

what is cytokinesis?

Answer 14

the cytoplasm is constricted by a ring of actin producing a cleavage furrow that pushes the cell into two

Question 15

what is the mitotic index

Answer 15

the percentage of cells undergoing mitosis in the sample

Question 16

how do you calculate the mitotic index?

Answer 16

the number of cells undergoing mitosis/ total number of cells in the field

Question 17

what are mitotic spindle fibres composed of?

Answer 17

microtubules

Question 18

at what stage in the cycle will there be the most DNA content

Answer 18

after S and before G2

Question 19

where is the G1 checkpoint and what does it check?

Answer 19

towards the end of the G1 phase and monitors cell size

Question 20

where is the G2 checkpoint and what does it check?

Answer 20

at the end of G2 phase an checks the success of DNA replication

Question 21

where is the M checkpoint and what does it check?

Answer 21

during metaphase and and monitors chromosome alignment

Question 22

what is the p53 gene?

Answer 22

involved in the g1 checkpoint. codes for a protein that checks replicated DNA strands are undamaged

Question 23

what protein is used at the G2 checkpoint?

Answer 23

Mitosis promoting factor - MPF - mitosis will only be triggered is sufficient MPF is present