Control of Cell Division and Cell Growth

Question 1

What is the role of Mitogens ?

Answer 1

Stimulate Cell division by triggering a wave of g1/S- cdk activity .

Which relives intracellular negative controls that otherwise block progress through cell cycle

Question 2

What is the role of growth factors ?

Answer 2

Stimulate cells growth ( cell mass) by promoting synthesis of proteins /inhibiting proteolysis

Question 3

What is the role of Survival Factors ?

Answer 3

Promote cells survival by suppressing the form of programmed cell death called apoptosis .

Question 4

What do Extracellaur Proteins acts like ?

Answer 4

They act like mitogens to promote cell cycle entry

For an animal cell to proliferate it must receive a stimulatory extracellular signals in the form of mitogen from other cells , neighbours usually

Mitogen overcome intracellular breaking mechanism that block progress through cell cycle

Question 5

What is one of the example of Mitogen Platelet - Derived growth factor ?

Answer 5

They release various factors, stimulate wound healing

Serum , support cells proliferation platelets contain one or more mitogens

PDGF - Stimulates cells division during wound healing stimulate many types of cells such as fibroblasts

Stimulate Cell growth , survival , differentiation or migration depending on the circumstances

Question 6

What does Epidermal Growth factor ?

Answer 6

Acts an epidermal cells but also on many other cells such as epithelial cell as well as non -epethial

Question 7

What about Insulin like growth factor ?

Answer 7

Plays a role in childhood growth , anabolic effects in adults

Receptors named after ligands - Receptor tyrosine kinase and EGF

Question 8

Can cells enter a specialised non -dividing state ?

Answer 8

In the absence of a mitogenic signal to proliferate

Cdk inhibition in G1 is maintained by multiple mechanism

Question 9

What are some of the cells in G0 state ?

Answer 9

Liver cells are in G0 , but can be stimulated to divide if the liver cell is damaged other types include fibroblasts and lymphocytes

Question 10

How do Mitogens control rate of cell division ?

Answer 10

By acting in the G1 phase of the cell cycle

They also release the brakes on CDK activity allowing entry into a new cell cycle

Question 11

What is the role of Myc ?

Answer 11

Thought to promote cell cycle entry by several mechanism , one of which is to increase the expression of genes incoding G1, Cylins ( D -cylins ) thereby increasing G1 - CDK ( Cylin D- Cdk4) activity

Major role - Stimulating he transcript of genes increases cell growth .