Chapter 8: Cell Communication

Question 1

What is another name for cell communication?

section 8.1

Answer 1

Cell Signaling

section 8.1

Question 2

What are the functions of cell communication/signaling?

section 8.1

Answer 2

1) Responding to incoming signals
2) Producing outgoing signals

section 8.1

Question 3

What are the 5 different types of cell communication/signaling?

section 8.1

Answer 3

1) Direct Intercellular Signaling
2) Contact Dependant Signaling
3) Autocrine Singaling
4) Paracrine Signaling
5) Endocrine Signaling

section 8.1

Question 4

What is the difference between Paracrine Signaling and Autocrine Signaling?

section 8.1

Answer 4

Both release signals to nearby target cells around them, but autocrine also send signals that effect themselves; pararine only sends signals that effect others.

section 8.1

Question 5

How does Direct Intercellular Signaling occur?

section 8.1

Answer 5

Allows signals to pass directly from cell to cell through gap junctions

GAP JUNCTION: Tunnels between two cells that connect them

section 8.1

Question 6

How does Contact Dependant Signaling occur?

section 8.1

Answer 6

Molecules bind to the surface of a cell and serve as signals when they come in contact

section 8.1

Question 7

How does Endocrine Signaling occur?

section 8.1

Answer 7

Hormones are released into the blood

Think of the ENDOCRINE SYSTEM (hormonal)

section 8.1

Question 8

What are the three stages in which cells respond to signals?

Section 8.1

Answer 8

1) Receptor Activation
2) Signal Transduction
3) Cellular Response

Section 8.1

Question 9

Explain Receptor Activation

This is the first step of response to cell signaling

Section 8.1

Answer 9

A signaling molecule binds to a cell, which then goes under a structural change in its reception which in turn activates

Section 8.1

Question 10

Explain Signal Transduction

This is the second step of response to Cell Signaling

Section 8.1

Answer 10

The now activated receptor stimulates a series of proteins and form a signal transduction pathway

Section 8.1

The receptor was activated by Receptor Activation, the first step of response to cell signaling.

Signal Trandsuction Pathway: A pathway for signals to go from the exterior of the cell into the interior of the cell

Question 10

Explain Cellular Response

This is the third and final step of response to Cell Signaling

Section 8.1

Answer 10

The formation of the Signal Trandsuction Pathway (from Signal Trandsuction) effect the function and amount of cellular proteins, which in turn create a cellular response from signals.

Section 8.1

Signal Transduction Pathway: A pathway for signals to go from the exterior of the cell into the interior of the cell

Question 11

What is a Ligand?

Section 8.2

Answer 11

A signaling molecule;
binds (non-covalently) to a receptor with high specificity.

Section 8.2

Question 12

How does Ligand Binding change receptors?

Section 8.2

Answer 12

When a signal molecule (Ligand) is binded to the receptor, it changes it’s structure to allow the signal to go through the membrane

Section 8.2

Question 13

TRUE or FALSE: The bond between a ligand and a receptor will stay stable for long periods of time.

Section 8.2

Answer 13

FALSE; Ligand/Receptor bonds will dissociate over a period of time.

Section 8.2

Dissociate: to Disconnect/Seperate

Question 14

What do brackets [ ] refer to in Receptor Activation ?

Section 8.2

Answer 14

The concentration of either a Ligand or a Receptor

Section 8.2

Question 15

What does K-on signify?

Section 8.2

Answer 15

The rate at which binding occurs

Section 8.2

Question 16

What does K-off signify?

Section 8.2

Answer 16

The rate at which Ligand/Receptor bonds dissociate

Section 8.2

Dissociate: Disconnect/Seperate

Question 17

What does K-d signify?

Section 8.2

Answer 17

The measure of affinity Receptors have for Ligands.

The Kd value is inversely related to the affinity between the
ligand and its receptor

Section 8.2

Affinity: tendency to attach with each other

Question 18

What is the K-d equation when it is at equilibrium?

Section 8.2

Answer 18

K-off/K-on

At equilibrium K-d = K-off/K-on

Section 8.2

Question 19

What is the Ligand concentration of K-d?

Section 8.2

Answer 19

K-d can be interpreted as 50% of receptors have Ligand bonds

Section 8.2

Question 20

What happens when Ligand concentration is above K-d value? Below?

Section 8.2

Answer 20

When ligand concentration is high, more receptors are to have ligand bonds and vice versa

Section 8.2

Question 21

What kind of signaling molecules do Cell Surface Receptors detect?

Section 8.3

Answer 21

Extracellular Signals;

Signaling molecules that are hydrophilic or too large to pass through the cell membrane

Section 8.3

Cell Surface Receptors detect hydrophilic signaling molecules because if they were hydrophobic they would pass through the membrane and react inside the cell instead.

Question 22

What are the three types of Cell Surface Receptors?

Section 8.3

Cell Surface Receptors: Receptors that detect signals from outside the cell

Answer 22

1) Enzyme-linked Receptors
2) G-Protein-Coupled Reactors
3) Ligand-gated Ion Channels

Section 8.3

Question 23

What are the two domains of Enzyme-Linked Receptors?

Section 8.3

Answer 23

1) Extracellular Signal-Binding
2) Intracellular Catalytic Domain

Section 8.3

Question 24

What happens during Extracellular Signal-Binding ?

Section 8.3

This is the first step of Enzyme-Linked Receptors

Answer 24

An enzyme binds to a receptor which goes through phosphorylation which activates the Intracellular Catalytic Domain

Section 8.3

Intracellular Catalytic Domain: the location of the second step of Enzyme-Linked Receptors
Phosphorylation: alters the structure/function of a protein

Question 25

What happens in the Intracellular Catalytic Domain?

Section 8.3

The second step of an Enzyme-Linked Receptor reaction

Answer 25

After the catalytic domain is activated it acts as a protein kinase, and it transfers the phosphate group of ATP to a protein.

Section 8.3

The Catalytic Domain was Activated during Extracellular Signal-Binding where an enzyme binds to a receptor, causing it to go through phosphorylation

Question 26

What kind of proteins do G-Proteins-Coupled-Receptors (GPCR’s) interact with and what is it’s function?

Section 8.3

Answer 26

G-Proteins: bind GDP to make GTP

Section 8.3

Question 27

What happens to the G-proteins after it turns GDP to GTP?

Section 8.3

Answer 27

The G-protein breaks into two sections:
α subunit and β/γ dimer, both promote cellular response

Section 8.3

Question 28

What is a Ligand-Gated Ion Channel?

Section 8.3

Answer 28

A channel located on the plasma membrane that opens once a signaling molecule is attached to it and allows the flow of ions

Section 8.3

Ligand-Gated Ion Channels use facilitated diffusion

Question 29

Where are Intracellular Receptors found?

Section 8.4

Answer 29

Found within in the cytosol or nucleus

Section 8.4

Question 30

What is the difference between Intracellular Receptors and Extracellular Receptors?

Section 8.4

Answer 30

Intracellular receptors are found within the cell while Extracellular are found outside the cell

Section 8.4

Question 31

What kind of signaling molecules bind to Intracellular Receptors? Why?

Section 8.4

Answer 31

Small and Hydrophobic signaling molecules, because these signals pass through the hydrophilic membrane and go into the cell, where the Intracellular Receptors are located

Section 8.4

Question 32

What does the activation of an Intracellular Receptor typically lead to?

Section 8.4

Answer 32

Gene Expression
(ESTROGEN/TESTOSTERONE)

Section 8.4