Chap 5(Signal Transduction Mechanisms)

Question 1

What is signal transduction mechanism?

Answer 1

Process by which messenger binding to receptor produces response in target cell

Question 2

Signal transduction mechanism differs based on what ?

Answer 2

whether messenger is lipophilic or lipophobic

Question 3

Lipophillic Messenger located where?

Answer 3

Receptor inside cell

Question 4

Lipophobic messenger located where?

Answer 4

Receptor on plasma membrane

Question 5

Lipophillic messengers bind to receptor where? What occurs if it is in cytoplasm?

Answer 5

In cytoplasm or nucleus.

Receptor :messenger complex enters nuclues

Question 6

Lipophobic messengers bind to what?

Answer 6

Membrane-bound receptors

Question 7

Define signal transduction.

Answer 7

the transmission of molecular signals from a cell’s exterior to its interior

Question 8

Lipophobic messengers , receptors fall into three categories, name them.

Answer 8

Channel linked receptors
Enzyme linked receptors
G protein linked receptors

Question 9

What is a channel linked receptor

Answer 9

Receptor that opens/closes ion channels in response to messenger binding

Question 10

Can gated ion channels open and close?

Answer 10

Yes.

Question 11

Ligand- gated channels open or close in response to what?

Answer 11

Binding of ligand to receptor

Question 12

What is a ligand?

Answer 12

Messenger that bind to recepto/channel

Question 13

Channel-linked receptor is what ?

Answer 13

Type of ligand- gated channel

Question 14

Open channel means what ?

Answer 14

Increased permeability

Question 15

Fast channels mean what

Answer 15

Receptor and channel are the same protein

Question 16

Slow channels mean what?

Answer 16

Receptor coupled to channel by G protein

Question 17

What is the role of calcium in signal transduction (4)

Answer 17

Changes electrical properties of cell
Induces muscle contraction
induces secretion by exocytosis
binds to calmodulin

Question 18

Ca-Calmodulin complex activates what ?

Answer 18

Protein Kinase

Question 19

Calcium levels cytosol and extracellular fluid

Answer 19

Lower in cytosol

Question 20

Calcium level is maintained at low level because of:

Answer 20

1. active transport of calcium across membrane.
2. Sequestration of calcium by binding with proteins in cytosol.
3. active transport of calcium into certain organelles( Smooth endoplasmic reticulum and mitochondria)

Question 21

How are calcium levels in cytosol increased?

Answer 21

by opening ion channels or releasing intracellular stores

Question 22

Enzyme linked receptors special how?

Answer 22

Function as enzyme and receptor

Question 23

Most enzyme linked receptors are

Answer 23

tyrosine kinase

Question 24

Purpose of G protein

Answer 24

function as links between G-protein-linked receptors and other proteins in plasma membrane called effectors.

Question 25

What is a second messenger?

Answer 25

An intracellular messenger produced by binding of an extracellular messenger to a receptor

Question 26

How is second messnger produced? Involves what?Purpose?

Answer 26

Binding of first messenger to receptor leads to production of second messenger in the cytosol. G-proteins. Amplification.

Question 27

What is phosphodiesterase?

Answer 27

Enzyme that degrades c-AMP

Question 28

What is the amplifier enzyme?

Answer 28

Guanylate Cyclase

Question 29

What is Phosphatidylinositol biphosphate (PIP2)

Answer 29

Membrane phospholipid

Question 30

What is phospholipase C? Activated by what?

Answer 30

Amplifier enzyme. G protein.

Question 31

How does termination of message occur?

Answer 31

Enzymatic degradation of messenger
Diffusion of messenger away from receptor
Internalization of messenger-receptor complex
Removal of calcium from cytosol

Question 32

How does signal transmission occur in endocrine system?

Answer 32

Endocrine gland releases hormone into blood

Travels to distant target cells