BIO310H5 Lecture Notes - Lecture 7: Protein Kinase A, Protein Kinase, Lipid Bilayer

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10 Feb 2018

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Related Questions

Which of the following is not true regarding G-protein associated receptors?

A. They can activate or inhibit adenylyl cyclase enzymes

B. They are c ell surface receptors that mediate action of peptide (protein) hormones

C. A hormone will bind irreversibly to a protein receptor.

D. The G protein is composed of Î±, Î² and Ï subunits and it is the alpha subunit that usually binds to GTP to separate and activate membrane bound enzymes.

QUESTION 1

Which of the following is an example of an extracellular signal molecule?

	a.	IP₃
	b.	cAMP
	c.	Insulin
	d.	Diacylglycerol

2 points

QUESTION 2

Nuclear hormone receptors _____

	a.	Bind to water soluble ligands
	b.	Activate second messengers
	c.	Regulate transcription in response to ligand binding
	d.	Are normally located on the plasma membrane

2 points

QUESTION 3

Which of the following does not occur when a receptor tyrosine kinase is bound by ligand?

	a.	Phosphorylation of the RTK
	b.	Cytoplasmic proteins bind the phosphorylated RTK
	c.	Dimerization of the RTK
	d.	The RTK binds to DNA to regulate transcription

2 points

QUESTION 4

Which of these is a logical signal-transduction pathway?

	a.	An intracellular receptor activates phospholipase C, which cleaves a membrane protein to form IP₃, which then activates the opening of an ER channel protein, which releases cyclic AMP into the cytoplasm, where it binds to an intracellular enzyme that carries out a response.
	b.	A G-protein-linked receptor activates G protein, which activates phospholipase C, which cleaves a membrane lipid to form IP₃, which binds to a calcium channel on the ER, which opens to release calcium ions into the cytoplasm, which bind to an intracellular enzyme that carries out a response.
	c.	An ion-channel receptor opens, allowing a steroid hormone to enter the cell; the steroid hormone then activates protein kinases that convert GTP to GDP, which binds to an intracellular enzyme that carries out a response.
	d.	A tyrosine-kinase receptor activates adenylyl cyclase, which activates phospholipase C, which converts ATP into cyclic AMP, which binds to an intracellular enzyme that carries out a response.

2 points

QUESTION 5

Which of the following is an example of signal amplification?

	a.	activation of an enzyme molecule
	b.	activation of a specific gene by a growth factor
	c.	Breakdown of many cAMP molecules
	d.	activation of 100 molecules by a single signal binding event

2 points

QUESTION 6

Consider a signal transduction pathway that utilizes cAMP as a second messenger to activate PKA (Protein Kinase A). Which of the following situations will result in the cellular response?

		The G protein releases GDP and binds to GTP
		The target protein (adenylyl cyclase) is inactive
		The regulatory subunits of PKA (Protein Kinase A) are bound to the catalytic subunits
		The appropriate G protein is bound to GDP

2 points

QUESTION 7

Which of the following is found in only some signal transduction pathways? [In other words, which is not found in all signal transduction pathways?]

		Receptor protein
		Extracellular signal molecule
		Intracellular signaling molecule
		Cellular response
		Effector protein

2 points

QUESTION 8

The enzyme that specifically catalyzes the conversion of ATP to cAMP is:

		Adenylyl phosphatase
		Adenylyl kinase
		Adenylyl dehydrogenase
		Adenylyl cyclase

2 points

QUESTION 9

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

		It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
		It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
		It would employ a transduction pathway directly from an external messenger.
		It would be able to carry out reception and transduction but would not be able to respond to a signal.

2 points

QUESTION 10

A hormone signal is sent from the brain to other parts of the body via the bloodstream. Why do only certain cells respond to this signal?

		Hormones do not last long enough in the bloodstream to stimulate a cellular response
		Only cells that have a specific transcription factor gene will be able to respond to the signal
		Only cells in the immediate vicinity of the cell sending the signal will respond
		Only cells that have a receptor for the specific signal will be able to respond to it

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Question 22

What intrinsic enzymatic activity do G proteins have?

They are ATPases

They are glycosidases

They are GTP synthases

They are GTPases

Question 23

How are G proteins activated?

The GTP dissociates from the G protein and GDP associates with the G protein

The GDP dissociates from the G protein and GTP associates with the G protein

The G protein synthesizes GTP from GDP

The G protein synthesizes GTP from ATP

Question 24

How are G proteins inactivated?

Hydrolyze ATP

Bind GTP

Bind ATP

Hydrolyze GTP

Question 25

What is a GTPase activating protein (GAP)?

It hydrolyzes GTP

It promotes release of GDP and binding of GTP of a G protein

It speeds up the rate of GTPase activty of a G protein

Question 26

What is a guanine nucleotide exchange factor (GEF)?

It speeds up the rate of GTPase activty of a G protein

It hydrolyzes GTP

It promotes release of GDP and binding of GTP to a G protein

Question 27

Which of the following types of enzyme activate G proteins?

GAP

GEF

Question 28

Which of the following types of enzyme inactivate G-proteins?

GAP

GEF

Question 29

What is receptor internalization and recycling?

It is when the receptor is co-translationally imported into the ER before being degraded by the unfolded protein response

It is when the receptor is endocytosed and then the vesicle fuses with the endosome, releases ligand and the receptor is returned to the plasma membrane

It is when the receptor is digested with proteases into amino acids and those amino acids are used to synthesize a new receptor

It is when the receptor cycles in and out of the nucleus

Question 30

How do large proteins get into the nucleus?

Simple diffusion

Facilitated diffusion through the nuclear pore

Active transport through the nuclear pore

Question 31

How easy is it for the following reaction to occur?

ADP + Pi â ATP

This is very exergonic and highly favorable

This is very endergonic and highly unfavorable

This is slightly exergonic and somewhat favorable

Question 32

The hydrolysis of ATP is highly...

Exergonic

Endergonic

BIO310H5 Lecture Notes - Lecture 7: Protein Kinase A, Protein Kinase, Lipid Bilayer

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