Lecture 20

Question 1

Cell to cell signaling regulates what?

Answer 1

gene expression
metabolism
cell shape and cellular migration
neuronal signaling

Question 2

What are the properties of cell surface receptors?

Answer 2

hormone hydrophilic
extracellular domain for binding 
intracellular domain is for signal transduction
have secondary messengers 
rapid response

Question 3

examples of ligands that use cell surface receptors?

Answer 3

insulin
glucagon
epinephrine
acetylcholine

Question 4

What are properties of intracellular receptors?

Answer 4

lipophilic (diffuse through membrane)
located in the cytoplasm or nucleus 
conformational change on binding
H-R complex enters nucleus 
bind to specific regions of the DNA 
influence gene expression
response is much slower

Question 5

Examples of ligands that use intracellular receptors?

Answer 5

steroid hormones

thyroxine
vitamin A and D

Question 6

What are the three types of intercellular signals?

Answer 6

1. endocrine
2. autocrine
3. paracrine

Question 7

Explain endocrine signaling and examples of ligands?

Answer 7

hormone is secreted into the blood

Ex: insulin

Question 8

Explain autocrine signaling and an example?

Answer 8

self activation or repression

Ex: growth factors

Question 9

Explain paracrine signaling and an example?

Answer 9

secretion of molecules to nearby cells

Ex: neurotransmitters

Question 10

What are the features of intracellular signal-transduction?

Answer 10

1. Specificity
2. Amplification
3. desensitization and adaptation
4. integration

Question 11

What are the four basic types of signal transduction pathways?

Answer 11

1. intracellular receptor (steroid receptor)
2. gated ion
3. receptor enzyme (catalytic receptor)
4. receptors that form intracellular secondary messengers

Question 12

Examples of ligands that use intracellular receptors?

Answer 12

1. testosterone, estrogen, cortisol, aldosterone
2. vit A and D
3. thyroid hormone

Question 13

What is the steroid receptor mechanism?

Answer 13

1. hormone diffuses into the cell
2. binds to its specific receptor
3. H-R complex enters nucleus and binds to specific region
4. can lead to induction or repression of a gene

slow response

Question 14

How does a ligand gated channel work?

Answer 14

binding of the ligand leads to the opening of the channel

results in an influx of ions

alters membrane potential

Question 15

examples of ligand gated channels?

Answer 15

1. nicotinic ACh
2. glutamate receptors
3. GABA-A receptors
4. glycine receptors

Question 16

How does the tryosine kinase receptor work? What kind of receptor is it?

Answer 16

It is a catalytic receptor

1. ligand binds
2. receptor is activated
3. The receptor is phosphorylated with kinase

Question 17

How does the insulin receptor work?

Answer 17

1. insulin binds to the receptor
2. insulin actives the receptor
3. The receptor is phosphorylated or activated

tyrosine kinase is what activates the receptor

Question 18

What are the cellular responses to insulin binding to the tyrosine kinase receptor?

Answer 18

increased glucose intake
regulation of transcription
activation of enzymes and regulation of metabolism

Question 19

Explain the process of GLUT-4 and insulin interaction?

Answer 19

1. insulin binds to the receptor
2. GLUT 4 translocated from the golgi to the PM
3. Vesicle containing GLUT4 binds and fuses with PM
4. glucose transport allowed in response
5. insulin dissociates; inactivation
6. vesicle containing GLUT4 translocates back to golgi

Question 20

What types of receptors form second messengers?

Answer 20

G-protein couple receptors

guanylate cyclase (cGMP)

Question 21

What are examples of G-protein receptors?

Answer 21

1. Alpha1 adrenergic receptor

activates phospholipase C
increases IP3, DAG, and Ca

2. Alpha2 adrenergic receptor (inhibitory)

inhibits adenylate cyclase and decreases cAMP levels

3. beta-adrenergic receptor (stimulatory)

activates adenylate cyclase and increases cAMP levels