Lecture 12 - Cell Communication

Question 1

The enzyme that catalyzes the splitting of PIP2 into two molecules of inositol triphosphate (IP3) and diacylglycerol in cell signaling, is:

Answer 1

Phospholipase C

Question 2

The major second messengers are

Answer 2

cAMP, cGMP, DAG

Question 3

Small charged molecules, often biogenic amines function as

Answer 3

Hormones, neurotransmitters

Question 4

Two key organizing principles for large multicellular organisms are

Answer 4

cell specialization and communication between cells

Question 5

Which of the following is not a type of signaling molecule?

Answer 5

Adenylate cyclase

Question 6

The binding of ligands to many G-proteins linked receptors leads to shortlived

Answer 6

Increase in the concentration of certain intracellular signaling molecules called second messenger

Question 7

The signaling molecules called steroid hormones

Answer 7

Are made in one location of the body but have their effects some distance away

Question 8

When a __________ reaches its __________ , there is a specific means of receiving it and acting on the message. This task is the responsibility of specialized proteins called __________ .

Answer 8

Signaling molecule; target cell; receptors

Question 9

In the signal transduction mechanism known as protein phosphorylation

Answer 9

• The signaling molecule binds to a surface receptor
• Receptor kinases play a key role in triggering the signal cascade
• Phosphorylated proteins act with enzymes to trigger the signal cascade

Question 10

What is a second messenger?

Answer 10

• Inositol 1,4,5 - triphosphate
• Diacyl glycerol

Question 11

In paracrine signaling, the signaling molecules affects only

Answer 11

Target cells close to the cell from which it was secreted

Question 12

cAMP and cGMP are derived from

Answer 12

ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively

Question 13

A cell is known to respond to a particular signaling molecule. Which of the following must be true of this cell?

Answer 13

It contains the receptor for the signaling molecule

Question 14

The hormone or ligand can be considered as:

Answer 14

First messenger

Question 15

Which of the following statements about G proteins is false?

Answer 15

They become activated when bound to GDP

Question 16

A signal cascade induced by adrenaline or thyroxine

Answer 16

• Must begin with receipt of the signal molecule by a surface receptor
• Involves the activation of a G protein
• Results in the activation of a sequence of enzymes needed for the cell effect

Question 17

SH2 domains specifically bind to

Answer 17

Phosphorylated tyrosine residues

Question 18

Which of the following is true about a hydrophilic signaling molecule?

Answer 18

It might trigger a signal cascade that causes some effect in a cell

Question 19

Which of the following is a hormone whose action requires a cell surface receptor?

Answer 19

Adrenaline