Block 2 Lecture 9 : The Cell Cycle & Cancer

Question 1

During which specific phase does the cell duplicate organelles and cytostolic components

Answer 1

G1 phase of Interphase

Question 2

during which phase does the cell replicate DNA and centrosomes

Answer 2

S phase of interphase

Question 3

during which phase are enzymes and other proteins synthesised

Answer 3

G2 phase

Question 4

which phase: nuclear envelope breaks down, nucleolus dissolves, mitotic spindle connects to kinetochores

Answer 4

prometaphase

Question 5

during which phase does the centromere split, with chromatids being dragged to either centrosome

Answer 5

anaphase

Question 6

which phase: chromatin condenses into chromosomes and mitotic spindle starts to form

Answer 6

prophase

Question 7

which phase: microtubules align chromosomes on metaphase plate

Answer 7

metaphase

Question 8

which phase: chromosomes revert to chromatin, nuclear envelope reforms, nucleolus reappears, mitotic spindle breaks down

Answer 8

telophase

Question 9

what is the name of the ring that pinches the plasma membrane during cytokinesis to separate the two cells?

Answer 9

actin-myosin ring

Question 10

what is an example of a cell cycle regulatory molecule and how does it act to regulate the cell cycle

Answer 10

MPF, mitosis promoting factor, induces mitosis

Question 11

what are the two polypeptide subunits of an MPF?

Answer 11

CDK protein kinase, cyclin

Question 12

what is the function of CDK

Answer 12

cyclin dependent kinase catalyses the phosphorylation of a target protein by ATP

Question 13

how do the concentrations of CDK and cyclin vary during the cell cycle

Answer 13

CDK remains much the same, cyclin concentration increases during interphase, peaks during Mitosis and then decreases

Question 14

because of the dependency of a CDK on _____, the levels of phosphorylation of the CDK and hence the activity of the MPF and hence the incidence of mitosis are controlled by ______

Answer 14

cyclin

Question 15

is MPF activated when cyclin is phosphorylated or unphosphorylated

Answer 15

unphosphorylated cyclin is the activated form

Question 16

what are three things that an activated MPF phosphorylates in order to kickstart mitosis

Answer 16

phosphorylates: chromosomal proteins to initiate the M phase, lamins to initiate nuclear envelope degradation, microtubules to initiate mitotic spindle

Question 17

MPF activates a protein which catalyses the _____ of the MPF cyclin

Answer 17

degradation

Question 18

MPF is disassembled when ____________ polyubiquitinates cyclin B/ CDK1

Answer 18

APC, anaphase promoting complex

Question 19

when does cyclin degradation begin

Answer 19

shortly after the beginning of anaphase

Question 20

what is the mechanism that degrades MPF

Answer 20

negative feedback

Question 21

In our bodies, without effective _________, cells will keep growing and form a tumour

Answer 21

cell cycle checkpoints

Question 22

protooncogenes normally function by promoting appropriate progression through the cell cycle. However they can be mutated rendering them active, a ______

Answer 22

oncogene

Question 23

This mutated oncogene will produce a hyperactive _____, which gives its own cell growth signals

Answer 23

Ras protein

Question 24

The Ras protein will result in the ______ of a protein that stimulates the cell cycle

Answer 24

transcription

Question 25

Tumour supressor proteins ____ cell division but when mutated may lose this ability

Answer 25

inhibit

Question 26

tumour suppressor protein mutation occurs when there is a defective or missing form of transcription factor _____, so transcription of the inhibits protein does not continue

Answer 26

p53

Question 27

APC degrades MPF therefore is a _____ gene

Answer 27

tumour supressor

Question 28

name the three stages of tumour growth from smallest to largest

Answer 28

polyp - adenoma - carcinoma

Question 29

which of the three stages of tumour growth is malignant?

Answer 29

carcinoma

Question 30

what is metastatic cancer

Answer 30

cancer that has spread via the blood or nymph to other parts of the body