Chapter 7.4.1 (Exam 4) Signal Response

Question 1

What are some different ways that cells can respond to signals?

Answer 1

Differential gene expression

Opening ion channels

Changing enzyme activity

Question 2

How can ion channels function as signal receptors?

Answer 2

By responding to signals by opening or closing

Question 3

What are two ways enzymes may be modified in signaling pathways?

Answer 3

Phosphorylation by a protein kinase changes enzyme shape - covalent change

cAMP binds noncovalently to an enzyme to change its shape

Question 4

Which enzyme performs phosphorylation?

Answer 4

Protein kinase

Question 5

What happens when enzymes are modified in signaling pathways?

Answer 5

Their active sites are exposed

Question 6

Which two enzymes are phosphorylated in the protein kinase cascade in liver cells stimulated by epinephrine?

Answer 6

Glycogen synthase and phosphorylase kinase

Question 7

What is the role of glycogen synthase in liver cells during the protein kinase cascade?

Answer 7

Prevents glucose from being stored as glycogen

Question 9

Why are glycogen synthase and phosphorylase kinase activated after the liver cell is stimulated by epinephrine?

Answer 9

By preventing glucose from being stored as glycogen and breaking down existing glycogen reserves, the blood glucose is increased for energy in the fight or flight response