Protein Control of Cell Division 1.5

Question 1

what is the purpose of the cytoskeleton?

Answer 1

to give mechanical support and shape to cells

Question 2

what does the cytoskeleton consist of?

Answer 2

different protein structures:
-microtubules (found in all eukaryotic cells)

Question 3

what do microtubules control?

Answer 3

the movement of membrane-bound organelle and chromosomes

Question 4

what is required for division

Answer 4

remodelling of the cytoskeleton

Question 5

what is involved in the formation and breakdown of microtubules

Answer 5

the polymerisation and depolymerisation of tubulin

Question 6

what forms the spindle fibres that are active during cell division?

Answer 6

microtubules

Question 7

what does the cell cycle consist of?

Answer 7

interphase and mitotic (M) phase

Question 8

what is involved in the mitotic phase?

Answer 8

mitosis and cytokinesis

Question 9

name the four stages of mitosis

Answer 9

prophase, anaphase, metaphase and telophase

Question 10

how is the progession of the cell cycle controlled?

Answer 10

by checkpoints

Question 11

describe what happens at the G1 checkpoint

Answer 11

retinoblastoma protein (Rb) acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for DNA replication

Question 12

what causes the inhibition of the retinoblastoma protein (Rb)?

Answer 12

phosphorylation by G1 cyclin - CDK

Question 13

describe what happens at the G2 checkpoint

Answer 13

• success of DNA replication and any damage to DNA is assessed
• DNA damage triggers the activation of several proteins including p53 - stimulates DNA repair, cell arrest, cause cell death

Question 14

what does the metaphase checkpoint control?

Answer 14

the progression from metaphase to anaphase

Question 15

what may result in degenerative disease?

Answer 15

an uncontrolled reduction in the rate of the cell cycle

Question 16

what may result in the formation of a tumour?

Answer 16

an uncontrolled increase in the rate of the cell cycle

Question 17

what is proto-oncogene?

Answer 17

a normal gene - involved in the control of cell growth/division
- can mutate to form a tumour-promoting oncogene

Question 18

what triggers apoptosis?

Answer 18

cell death signals that can be external or internal

Question 19

how do external death signal molecules work?

Answer 19

they bind to a surface receptor protein and trigger a protein cascade within the cytoplasm

Question 20

how do internal death signal molecules occur?

Answer 20

it cause the activation of p53 tumour suppressor protein which has resulted from DNA damage

Question 21

true or false?

both types of death signal result in the activation of caspases that cause the destruction of the cell

Answer 21

true

Question 22

why is apoptosis essential during the development of an organism?

Answer 22

to remove cells no longer required as development processes or during metamorphosis

Question 23

why may cells initiate apoptosis?

Answer 23

due to the absence of growth factors

Question 24

what molecules are involved in regulating the cell cycle?

Answer 24

cyclin proteins that accumulate during cell growth