BIOL 2P03 Lecture 5: Week 5 Lecture

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orangemule782

16 Jun 2016

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In order to conduct cell signaling you need: Conformational change of the receptor protein once the signaling molecule has binded to the receptor. All centered around having specific signals and receptors that will result in conformational change = change in function = change inside the cell. Transduction = changing one form to another ie: chemical signal to electrical signal in the presence of neurotransmitters. Signal transduction: conversion of an extracellular signal into a cellular response. Cells must be able to change aspects of their structure/function in response to signals in their environment. Q] which of the following represents an exogenous chemical signaling molecule: hormone, neurotransmitter, anaesthetic, cytokine, all of the above. Physical signal: light move from their environment caring energy and carry photons to the receptor (exogenous, pressure, vibration, temperature (heat/cold) Endogenous vs. exogenous: endogenous = chemical signaling pathways, exogenous = physical signaling pathways. Endocrine signals = only activate specific cells that express the specific receptors.

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HUMAN GROWTH HORMONE

1. Describe the ligand and any external receptors that bind to the ligand. If signaling can occur without an external ligand, explain how this can occur.

2. Describe how the signal is translocated from the exterior of the cell to the interior of the cell. Be sure to describe the specific activity of the receptor in initiating the intracellular signal.

3. Describe the propagation of the signal within the cell from the membrane receptor to the point of cellular response. Provide the details for at least one specific protein interaction that either results in the activation or inactivation of a subsequent protein or signaling molecule to propagate the signal.

4. What is a specific cellular response to the signal. Something will change- what is it?

indigosea-lion999

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

cerisehedgehog846

The insulin receptor is a
a. phosphatase.
b. kinase.
c. phosphodiesterase.
d. cAMP molecule.
e. G protein.

What do the following receptors all have in common: G protein-linked receptors, protein kinases, and ion channels?
Select one:
a. Conformational change once the ligand is bound
b. Ligand binding
c. Amplification of the signal
d. All of the above

Diacylglycerol
Select one:
a. activates G proteins.
b. hydrolyzes phosphatidyl inositol-bisphosphate.
c. is released from the cell as a paracrine-signaling molecule.
d. opens Ca2+ channels.
e. activates protein kinase C

Gap junctions
Select one:
a. permit metabolic cooperation among linked cells.
b. are present on few copies per cell.
c. contain membrane lined bridges.
d. are channels about 1. 5 mm in diameter.
e. allow large molecules and ions to pass rapidly between cells.

Smooth muscle cells in the airways relax while those in the blood vessels contract in response to the hormone epinephrine. What would you expect to be different in these two types of cells exposed to epinephrine?
Select one:
a. Presence of epinephrine receptors.
b. Exposure to epinephrine released by neighboring cells.
c. Activation of protein kinases.
d. Rate of metabolism.
e. Types of proteins expressed.

The second messenger IP3
Select one:
a. is released from the cell as a paracrine-signaling molecule.
b. hydrolyzes phosphatidyl inositol-bisphosphate.
c. activates protein kinase C.
d. opens Ca2+ channels.
e. activates G proteins.

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BIOL 2P03 Lecture 5: Week 5 Lecture

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