Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OU Biochem Fall 2016 > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

What are the three steps of biosignaling and cell communication?

A
  1. Reception
  2. Transduction
  3. Response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two important parameters of each pair of signaling molecule & receptor?

A
  • Kd: dissociation complex

- Bmax: maximal binding capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the different types of effectors?

A

growth factors, hormones, neutrotrasmitters, ligands, signals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are characteristics of binding proteins?

A
  • specificity
  • amplification
  • modularity
  • desensitization/adaptation
  • integration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the concept of modularity?

A

each pathway contains multiple protein components that have multiple domains which can interact in multiple pathways; this provides flexibility in the regulation of these pathways

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the concept of desensitization?

A

each signal is transient; transduction is triggered but only lasts for a few seconds; thereafter even with the signal present, there is not response; reduction of receptors at cell surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the concept of integration?

A

each cell have multiple transduction pathways that leads to multiple cell responses; the response is dependent on all the signal combined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What kind of bond exists between a ligand and its receptor?

A

weak, reversible, noncovalent interactions: electrostatic, hydrogen-bonding, and Van der Waals’ interactions and the hydrophobic effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the constant / value that reflects the affinity of binding?

A

Kd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the constant / value that reflects the amount of receptors on cell surface?

A

Bmax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an agonist?

A

a drug that mimics the natural signal; binds to the receptor to trigger transduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is an antagonist?

A

a drug that binds to the receptor but does not trigger a response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many types of signaling mechanisms does multicellular organisms have and what are they?

A

There are six:

  • G protein coupled receptor
  • Receptor tyrosine kinase
  • Receptor guanylyl cyclase
  • Gated ion channel
  • Adhesion receptor (integrin)
  • Nuclear receptor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the different types of ion channels?

A
  • ligand-gated channels
  • voltage-gated channels
  • mechanically gated channels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the three important second messengers in ion channels and what do they do?

A
  • Cyclic AMP: opens channels in olfactory and gustatory cells
  • IP3 - opens calcium channels in ER membrane
  • cyclic GMP - keeps sodium channels open in rod outer segments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do G proteins do in ion channels?

A

open potassium channels in response to activation by receptors for various ligands, including acetylcholine, serotonin, dopamine, somatostatin, and g-aminobutyrate

17
Q

How is the insulin receptor different fromthe other receptor of tyrosine kinases?

A

it consists of an alpha and beta subunit; the alpha is responsible for binding of the subunit and the beta is responsible for kinase activity; also, it undergoes conformational chnage

18
Q

Except for the insulin receptor, what is the first step for all the other tyrosine kinase receptors and what happens after that?

A

dimerization which leads to autophosphorylation which activates the kinase activity to phosphorylate downstream products

19
Q

Does autophosphorylation happen in the cis or trans formation and why?

A

trans because they need to be facing each other to autophosphorylate each other

20
Q

How does phosphorylation of tyrosine kinase lead to activation?

A

the unphosphorylated kinase residues occupy the active sites ; when those tyrosine residues are phosphorylated, it undergoes conformational change and moves away from the binding site and the sites are now exposed

21
Q

T/F: Many SH2 proteins are adapter proteins.

A

True

22
Q

What are the ways in which the SH2 domain can propagate the growth factor signal?

A
  • recruiting binding partners to the membrane

- facilitating tyrosine phosphorylation

23
Q

Explain insulin signaling via the PI-3K/ PKB pathway.

A
  • insulin phosphorylates IRS-1
  • which activates PI3K
  • which converts PIP2 to PIP3
  • which binds to PKB
  • which phosphorylates GSK3 and inactivate it
  • GSK3, when activated, shuts down GS (glycogen synthase)
24
Q

How does phosphorylation of GSK3 inactivate it?

A

phosphorylation causes the serine residue to go conformational change and blocks the binding site

25
Q

How is PIP3 degraded back to PIP2?

A

PTEN (a lipid phosphatase) that acts to terminate the signaling pathway; without this, increase in cell proliferation and decrease in cell apoptosis

26
Q

Describe the epinephrine response via the cAMP pathway.

A

EPI binds to B-adrenergic receptor; this causes GDP to bind to intracellular complex; GDP falls off and GTP binds to G(sa) subunit which activates it; G(sa) unit falls off to bind to adenylyl cyclase which catalyzes formation of cAMP; cAMP activates PKA; PKA cause the cellular response to epinephrine

27
Q

How does cAMP activate PKA?

A

PKA consists of 4 subunits: 2 are regulatory and 2 are enzymatic; the binding to cAMP to the regulatory sites releases the enzymatic subunits

OU Biochem Fall 2016 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions