Cell Signaling

Question 1

What do multicellular organisms require in order to function?

Answer 1

precise internal communication

Question 2

exes of precise internal communication

Answer 2

o Example- animals have nervous systems in which neuronstransmit information electrically and chemically o Plants and animals have hormones as signals between cells andorgans

Question 3

Signal transduction

Answer 3

the process by which cells convert and amplify an extra-cellular signal into an intra-cellular signal

Question 4

Ligands

Answer 4

signaling molecules/first messenger

Question 5

Examples of signaling molecules:

Answer 5

Neurotransmitters (produced by nerve cells) Hormones

Question 6

First step of signaling

Answer 6

1- Synthesis and release of the signaling molecules

Question 7

Second step of signaling

Answer 7

2- Transport to target cells

Question 8

Third step of signaling

Answer 8

3- Reception of the information by target cells

Question 9

Fourth step of signaling

Answer 9

4- Signal transduction

Question 10

Fifth step of signaling

Answer 10

5- Response by the cell

Question 11

Sixth step of signaling

Answer 11

6- Termination of signaling

Question 12

Examples of cell signaling in unicellular bacteria, protists, fungi–amoeba

Answer 12

Amoeba-like cellular slime mold secretes cAMP (cyclic adenosine monophosphate) when food is scarce, causing other slime molds to come together and form amulticellular slug-shaped colony

Question 13

Examples of cell signaling in unicellular bacteria, protists, fungi–yeast

Answer 13

Yeast cells send out signals to mate with one another

Question 14

Examples of cell signaling in unicellular bacteria, protists, fungi–sperm

Answer 14

Sperm have receptors that respond to chemical signalsthat guide the sperm to the egg

Question 15

• Response by the cell– The activated enzyme can either

Answer 15

1. Catalyze the production of large numbers of intracellular signaling molecules, called second messengers2. Or it may activate intracellular enzymes called protein kinases

Question 16

protein kinases

Answer 16

enzymes that activate specific proteins by transferring phosphate groups to them from ATP

Question 17

second messengers, like___

Answer 17

cAMP (catalyzed by enzyme called adenylyl cyclase)

Question 18

Cell signaling

Answer 18

mechanism by which cells communicate with each other. One cell secretes ligand, which combines with receptors on a diff cell

Question 19

What synthesizes ligands?

Answer 19

Either synthesized by neighboring tissue or by

specialized tissue that may be far away

Question 20

Transport of ligands

Answer 20

by diffusion or via the circulatory system

Question 21

Reception of the information by target cells

Answer 21

Ligands bind to

receptors on target cells

Question 22

How can regulatory molecules transmit information to the cell without physically crossing the plasma membrane?

Answer 22

by using systems of interacting integral membrane proteins–Each component in signal transduction acts as a “switch”-activated or inactivated

Question 23

Receptor

Answer 23

transmembrane protein with 3

domains

Question 24

3 domains of receptor

Answer 24

One on extracellular surface, acts as docking site for ligand
Second extending through plasma membrane
Third is “tail” that extends into cytoplasm

Question 25

When ligand, or first messenger, binds to receptor, how does it activate it?

Answer 25

by changing the

shape of the receptor tail that extends into the cytoplasm

Question 26

What does the activated receptor do?

Answer 26

changes the conformation of a
second protein, sometimes called G protein,
which then becomes activated. GTP then turns into GDP, which releases energy.

Question 27

Why is 2nd protein called a G protein?

Answer 27

Called G protein
because when it’s in activated form, it is bound
to guanosine triphosphate (GTP- similar to
adenine).

Question 28

What happens after the activated receptor changes the conformation?

Answer 28

Eventually, this causes

activation of a specific enzyme bound to the membrane