BIOL3040 Lecture Notes - Lecture 23: Alpha Helix, Platelet-Derived Growth Factor, Endocytosis

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5 Apr 2017

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Lecture 23: you can express activated calmodulin and at the same time knock out protein x, then you assess what happens to cam kinase activity to see what happens downstream. If cam kinase is still active even though protein x is not functional, then it is upstream of calmodulin and does not affect its function. If it is not active, the protein x is downstream of calmodulin. Enzyme coupled receptors: rtk pathway are the most common enzyme coupled receptor pathways, play a role in cell division, cell survival, and cell growth, a screwed up pathway can cause cancer. Only happens when they are close: first identified as growth factors. Because they regulate cell division, survival, and differentiation: because response is relatively slow, they are slow to function, rtks. Phosphorylated receptor that is bound to the adaptor protein can bind to rasgef and bring rasgef in. Rasgef: catalyzes the exchange of gdp to gtp on the ras protein, signal keeps going.

Related Questions

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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Need help with biology questions:

1. To increase the excretion of an acidic drug, what would you do to the urine?

	A.	Make it more basic
	B.	None of the above
	C.	Make it neutral
	D.	Make it more acidic

2. G-Protein coupled receptors directly act on which of the following secondary messenger molecules:

	A.	cAMP
	B.	ATP
	C.	ADP
	D.	GTP
	E.	None of the above or more than one of the above

3. Drug A and Drug B both produce the same level of biological/physiological response. Drug A produces this effect with 100 mg/kg dose. Drug B produces this effect with 50 mg/kg dose. Which of the following is true?:

	A.	Drug B is more efficacious than Drug A. Both drugs are equally potent.
	B.	Drug A is more efficacious than Drug B. Both drugs are equally potent.
	C.	Drug A and B are equally efficacious. Drug A is more potent than Drug B.
	D.	Drug A and B are equally efficacious. Drug B is more potent than Drug A.

4. The stomach has a ______ pH, whereas the small intestines have a _______ pH. The colon has an approximately ___________ pH.

	A.	High; low; neutral
	B.	Low; high; neutral
	C.	Low; neutral; neutral
	D.	None of the above

5. Which receptor is most likely to reduce norepinephrine levels when activated?

	A.	alpha 2 adrenergic
	B.	alpha 1 adrenergic
	C.	dopamine D1 receptors

6. Which of the following statements are FALSE?

	A.	If the Vd of a drug is between 60 and 80 L the drug has likely distributed to the total body water of a 200 kg man.
	B.	In the enterohepatic system the activity of bacteria to remove conjugates from a drug in the gut will decrease the clearance of the drug.
	C.	Lipid drugs are more likely to be reabsorbed by the kidney from the urine.
	D.	A weak basic drug (pKa = 6) will be mostly ionized in urine of a pH= 3 and only the non- ionized drug will be eliminated.
	E.	The major conjugate in Phase 2 metabolism is glucuronide.

7. Isoproterenol (Î²-agonist) is a vasodilator that increases HR. What happens to systolic and diastolic pressures upon IV administration of isoproterenol?

	A.	â systolic; â diastolic
	B.	â systolic; â diastolic
	C.	â systolic; â diastolic
	D.	â systolic; â diastolic
	E.	None of the above

8. If you want to increase the blood concentration of a drug A, you can perform which of the following procedures:

	A.	Inhibit Drug A metabolism with Drug B
	B.	Enhance Drug A reabsorption from renal proximal tubule by changing ionization of Drug A with Drug B
	C.	Allow competition of Drug B with Drug A for active renal secretion processes
	D.	Increase the binding of Drug A to serum albumin
	E.	All of the above

9. Which of the following describes Phase I metabolism?

	A.	Inactive products are always produced in this phase.
	B.	Large molecules such as glucuronic acid are conjugated to drugs in this phase.
	C.	This phase may produce active metabolites from prodrugs.
	D.	This phase only occurs in the liver.

10. Which of the following is NOT an enzyme involved in the biosynthesis of biogenic amines?

	A.	Phenylethanolamine N-methyl Transferase
	B.	Dopamine Î²-hydroxylase
	C.	Tyrosine dehydroxylase
	D.	DOPA decarboxylase
	E.	All of the above

11. Why would an antibiotic at the same concentration be more active against bacteria in water than in serum or plasma? (Activity is measured in a test tube)

	A.	activity of the antibiotic is increased in water.
	B.	due to drug-protein interaction in serum
	C.	the antibiotic is more stable in water
	D.	all of the above
	E.	none of the above

12. Ion channels are targets for drugs. Which drug class targets Na+ channels?

	A.	Benzodiazepines
	B.	Beta blockers
	C.	Local anesthetics
	D.	Antihypertensive drugs (cardiac and smooth muscle)
	E.	Glibenclimide (diabetic drug)

13. _________________ not metabolized by catechol-O-methyltransferase (COMT).

	A.	Dopamine
	B.	Epinephrine
	C.	Phenylephrine
	D.	Norepinephrine
	E.	All of the above are metabolized by COMT.

BIOL3040 Lecture Notes - Lecture 23: Alpha Helix, Platelet-Derived Growth Factor, Endocytosis

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