chromosome segregation in mitosis

Question 1

cytokiness

Answer 1

cell middle contracts and separates

Question 2

centrosomes

Answer 2

an organelle near the nucleus of a cell which contains centrioles (in animal cells) and from which the spindle fibres develop

Question 3

M phase steps

Answer 3

1) chromosomes alignment
2) chromosome seperation
3) cell division

Question 4

sub phases of M phase

Answer 4

prophase, metaphase, anaphase, telophase

Question 5

prophase

Answer 5

• chromsomes condense and nuclear envelop disintegrates.

- spindle forms

Question 6

metaphase

Answer 6

• microtubules make contact with chromosomes

- chromosomes are positioned in one plane

Question 7

anaphase

Answer 7

microtubules and motors pull on the chromosomes

• chromatids move to the pole
• rapid elongation of spindle
• formation of contractile ring

Question 8

telophase

Answer 8

• cell middle contracts and separates
• chromosomes decondense
• nuclear envelope is formed

Question 9

which two mechanisms do microtubules use to move chromosomes

Answer 9

1) de/polymerisation of microtubules–> exerts force on attached chromosomes
2) molecular motors that act on the microtubules

Question 10

microtubules form from

Answer 10

centrosomes- which move to opposite poles during mitosis

Question 11

microtubules used in mitosis

Answer 11

kinetochore microtubules

Question 12

tests to probe microtubules are required for mitosis

Answer 12

Nocodazole (anti-microtubule drug) is used and the cell will not mites since the chromosomes will not be pulled tot he pop poles.

Question 13

nocadazole

Answer 13

anti-microtubule drug

Question 14

astral microtubules

Answer 14

connects centrioles to poles of the cell

Question 15

role of motors in spindle formation

Answer 15

• pulling on chromosomes exerts a ‘polar ejection force’

- -> myosin II is responsible for contraction at the contractile ring during cytokinesis

Question 16

which molecular motor is responsible for cytokinesis

Answer 16

myosin II

Question 17

where does cell contract during cytokinesis occur?

Answer 17

at the contractile ring

Question 18

contractile ring

Answer 18

forms near the cortex end of the anaphase

Question 19

the ring contains

Answer 19

myosin, actin, regulators and actin-binding proteins

Question 20

inhibition of myosin II

Answer 20

abolished cytokinesis–> showing how important it is

Question 21

checkpoints

Answer 21

perform a quality control function e.g. are the chromosomes attached to the spindle

Question 22

e.g. at G2/M–> ENTER M

Answer 22

is DNA replicated? is environment favourable?

Question 23

e.g.2 EXIT M

Answer 23

are the chromosomes attached?