Chapter 9 Unit 3

Question 1

State the two things communication between cells require.

Answer 1

1. Ligand 2. Receptor

Question 2

What are the four basic mechanisms for cellular communication?

Answer 2

1. Direct contact 2. Paracrine signaling 3. Endocrine signaling 4. Synaptic signaling.

Question 3

Describe direct contact

Answer 3

It is where ligand molecules on the surface of one cell are recognized by receptor molecules on an adjacent cell.

Question 4

Describe paracrine signaling

Answer 4

It is where ligands are released from a secretory cell bind to the receptors on adjacent cells.

Question 5

Describe endocrine signaling

Answer 5

It is where special ligands called hormones are released from the secretory cells and bind to the receptors on or within cells throughout the body.

Question 6

Describe synaptic signaling

Answer 6

It is where nerve cells release the signal ligands (neurotransmitters) which binds to receptors on nearby nerve or muscle cells.

Question 7

What are signal transduction?

Answer 7

It is the series of chemical reactions that occur following the binding of a ligand to a receptor.

Question 8

How does a cell respond when a ligand binds to a receptor?

Answer 8

Chemically

Question 9

What is kinase?

Answer 9

It is an enzyme that adds a phosphate to a protein therefore activating or turning it on.

Question 10

What is phosphatase?

Answer 10

It is an enzyme that removes a phosphate from a protein therefore deactivating or turning it off.

Question 11

What are the three AA that are frequent in phosphorylation?

Answer 11

Serine, Threonine, and Tyrosine.

Question 12

How many AA do you need for phosphorylation?

Answer 12

One of the three.

Question 13

Where are cell surface or membrane receptors located?

Answer 13

They are on the plasma membrane.

Question 14

Where is the intercellular receptor located?

Answer 14

It is located inside the cell.

Question 15

List the three classes of membrane receptors?

Answer 15

1. Channel linked or gated receptors 2. Enzymatic receptors 3. G protein- coupled receptors

Question 16

What is an enzyme receptor called?

Answer 16

Receptor tyrosine kinase

Question 17

`What two things happen when a signal ligand binds the membrane bound receptor?

Answer 17

It is dimerized and authphosphorylated.

Question 18

What happens after the membrane bound receptor is dimerized and authphosphorylated?

Answer 18

The activated receptor then adds a phosphate to tyrosine on a response protein.

Question 19

What is an example of a receptor tyrosine kinase?

Answer 19

An epidermal growth factor receptor which stimulates skin cells to replicate.

Question 20

What is Kinase cascade?

Answer 20

It is a series of protein kinases that phosphorylate each other in succession amplifying the signal, therefore a few signal ligand molecules can cause a large cell response.

Question 21

What is MAP kinases?

Answer 21

They stand for Mitogen-activated protein kinases.

Question 22

Where are MAP kinases typically?

Answer 22

They are typically in plant products.

Question 23

What is G-protein?

Answer 23

It is a protein bound to GTP.

Question 24

What is G-protein-coupled receptor (GPCRs)

Answer 24

Receptors bound to G proteins.

Question 25

G proteins is a what that can be turned on by a receptor?

Answer 25

A switch.

Question 26

Signal ligand binds receptor, then G protein activates a(n) what?

Answer 26

An effector protein usually an enzyme.

Question 27

Once activated what do effector proteins produce that then generates a cellular response?

Answer 27

A second messenger.

Question 28

What is a common effector protein which converts ATP to cAMP which then acts as a second messenger?

Answer 28

Adenylyl cyclase

Question 29

What are the other second messengers?

Answer 29

Inositol phosphates and calcium ions (Ca2+)

Question 30

What does it mean if one of the second messengers increase?

Answer 30

It means that the cell has been activated.

Question 31

What does Adenylyl cyclase at as after converting ATP to cMAP?

Answer 31

It serves as a second messenger to activate or inactivate proteins.

Question 32

What can steroid hormones do?

Answer 32

They can go across the membrane

Question 33

Where is calcium?

Answer 33

In the smooth ER.

Question 34

Steroid hormones are nonpolar so they can cross the plasma membranes and go to what?

Answer 34

Steroid receptor.

Question 35

What usually happens during the regulation of gene expression?

Answer 35

An inhibitor blocks the steroid receptor from binding to DNA until the hormone is present.

Question 36

What are the three functional domains of a steroid receptor?

Answer 36

1. Hormone-binding domain 2. DNA binding domain 3. Domain that interacts with coactivator to affect gene expression (activating or deactivating transcription)

Question 37

What does the steroid receptor signaling do?

Answer 37

It regulates gene expression.

Question 38

What are autoinducers?

Answer 38

They are small molecules produced by bacteria that regulates gene expression.

Question 39

What is Ligand?

Answer 39

It is a signaling molecule from the cell.

Question 40

What is a receptor?

Answer 40

It is a protein which the ligand binds to.

Question 41

What do pores do regarding direct contact?

Answer 41

They can open and close.

Question 42

Describe channel linked or gated receptors

Answer 42

The ion channel opens in response to ligand binding.

Question 43

Describe enzymatic receptors

Answer 43

The receptor is an enzyme that is activated by ligand binding.

Question 44

Describe G protein- coupled receptors

Answer 44

A G-protein ( protein bound to GTP) assist in transmitting signal.

Question 45

What are MAP kinases activated by?

Answer 45

They are activated by kinase cascades.

Question 46

Where is a receptor located?

Answer 46

It may be on the plasma membrane or within the cell.

Question 47

What happens when the shape of the receptor changes?

Answer 47

The function changes, and they become active.