Sequence Of Events Activating Entry Into S-Phase From G1

Question 1

The production of Cyclin E occurs early, and later Cyclin A

Answer 1

During G1

Question 2

What do growth factor receptors do when they are bound

Answer 2

They dimerize and phosphorylate tyrosines on each other (cross-phosphorylation)

Question 3

What docks at phosphotyrosine and positions SOS at the membrane where it activates Ras

Answer 3

The SH2 domain of Grb2

Question 4

Takes up GTP in exchange for GDP

Answer 4

Ras

Question 5

Activates Raf to begin kinase cascade leading to activation of MAPK

Answer 5

Ras/GTP

Question 6

Phosphorylates Cdk2 to activate it

Answer 6

MAPK (erk1)

Question 7

When bound to Cyclin E, it phosphorylates proteins to establish them to assemble at origins of replication.

Answer 7

Activated Cdk2

Question 8

Interacts with forming helicase complex to prevent premature initiation of replication

Answer 8

Treslin

Question 9

activates c-FOS to activate transcription of the Cyclin A gene

Answer 9

MAPK

Question 10

Also called “start kinase”

Answer 10

Cyclin A/ Cdk2

Question 11

Phosphorylates Treslin to negate its inhibitory function so that helicases begin opening up replication forks to begin replication

Answer 11

Cdk2