Michael Hynes

Question 1

Heirachy of stem cells

Answer 1

Totipotent –> pluripotent –> blood stem cells & other stem cells

Question 2

Yeast replication

Answer 2

1. Budding

2. Fission - s.pombe: equal cytokinesis

Question 3

Cell Growth

Answer 3

A) extracellular factor –> cell growth –> cell division
B) Growth factor –> cell grwoth
Mitogen –> cell division
C) Extracellular factor –> Cell growth & cell division

Question 4

Cell division without growth

Answer 4

E.g. Frogs

After fertilization, egg divides without growing

Question 5

Nuclear division without cell division

Answer 5

Fertilised egg–> nuclear divisions –> many nuclei in syncytium –> nuclei migrate to edge of cell –> cellular boundaries –> cellularization–>EMBRYO

Question 6

Apoptosis

Answer 6

DNA degraded, engulfed by macrophages

Question 7

Checkpoints

Answer 7

START checkpoint: enter cell cycle and proceed to S phase
G2/M: enter mitosis
Metaphase-anaphase transition: Triger anaphase and proceed to cytokinesis

Question 8

Cyclin

Answer 8

Key molecules in regulating cell cycle

Question 9

Mitosis promoting factor (MPF)=

Answer 9

Cyclin + cyclin dependent kinase (phosphorylates other proteins)

Question 10

Cyclin + cyclin dependent kinase

Answer 10

Present inactive –> partially active when associated with kinase (specific protein-protein interactions) –> phosphorylated by Cdk-activating kinase –> FULLY ACTIVE

Question 11

Diff cyclins

Answer 11

G1/S
S cyclin: S and G2
M cyclin: G2 and M

Question 12

Isolation of cell cycle mutants

Answer 12

Temp sensitive - mutagenesis
Random arrest FOR TS MUTANT

for cdc mutant:ALL ARREST AT PARTICULAR STAGE