Chap 5(Signal Transduction Mechanisms) Flashcards Preview

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Flashcards in Chap 5(Signal Transduction Mechanisms) Deck (32):
1

What is signal transduction mechanism?

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

2

Signal transduction mechanism differs based on what ?

whether messenger is lipophilic or lipophobic

3

Lipophillic Messenger located where?

Receptor inside cell

4

Lipophobic messenger located where?

Receptor on plasma membrane

5

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

In cytoplasm or nucleus.
Receptor :messenger complex enters nuclues

6

Lipophobic messengers bind to what?

Membrane-bound receptors

7

Define signal transduction.

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

8

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

Channel linked receptors
Enzyme linked receptors
G protein linked receptors

9

What is a channel linked receptor

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

10

Can gated ion channels open and close?

Yes.

11

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

Binding of ligand to receptor

12

What is a ligand?

Messenger that bind to recepto/channel

13

Channel-linked receptor is what ?

Type of ligand- gated channel

14

Open channel means what ?

Increased permeability

15

Fast channels mean what

Receptor and channel are the same protein

16

Slow channels mean what?

Receptor coupled to channel by G protein

17

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

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

18

Ca-Calmodulin complex activates what ?

Protein Kinase

19

Calcium levels cytosol and extracellular fluid

Lower in cytosol

20

Calcium level is maintained at low level because of:

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)

21

How are calcium levels in cytosol increased?

by opening ion channels or releasing intracellular stores

22

Enzyme linked receptors special how?

Function as enzyme and receptor

23

Most enzyme linked receptors are

tyrosine kinase

24

Purpose of G protein

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

25

What is a second messenger?

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

26

How is second messnger produced? Involves what?Purpose?

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

27

What is phosphodiesterase?

Enzyme that degrades c-AMP

28

What is the amplifier enzyme?

Guanylate Cyclase

29

What is Phosphatidylinositol biphosphate (PIP2)

Membrane phospholipid

30

What is phospholipase C? Activated by what?

Amplifier enzyme. G protein.

31

How does termination of message occur?

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

32

How does signal transmission occur in endocrine system?

Endocrine gland releases hormone into blood
Travels to distant target cells