BIOL 2021 Chapter Notes - Chapter 15.11: Cell Membrane, Membrane Transport Protein, Autocrine Signalling

53 views2 pages

lavendershark790

11 Feb 2018

School

York University

Department

Biology

Course

BIOL 2021

Professor

Patricia Lakin- Thomas

For unlimited access to Textbook Notes, a Class+ subscription is required.

Document Summary

Extracellular signal molecules: mediate the communication between cells in multicellular organisms. Receptor proteins specifically bind the signal/ligand: ligand can be on the plasma membrane or inside the cell. Receptor proteins activate one or more intracellular signaling pathways, involving a series of signaling proteins. At the end of an intracellular signaling pathway, effector proteins cause the appropriate effects from a signal. 4 forms of intercellular signaling differ in distance. Contact-dependent: signal molecule is on the surface of the cell and interacts with a neighbouring cell"s receptor protein: direct contact. Synaptic signaling: one neuron signal travels long distances to other neuron cells. Endocrine: endocrine cells secrete hormone signals that travel a long distance in the bloodstream to many other cells. Cell-surface receptors: hydrophilic signal molecule (water soluble) cannot cross the cell membrane on its own so it binds to a receptor on the cell-surface.

Related Questions

1. How does sexual reproduction compare to DNA transfers inprokaryotes?
I. Both increase genetic diversity.
II. Sexual reproduction results in greater evolutionarychange.
III. DNA transfer in prokaryotes allows for fewer errors andmutations.

a. I only

b. I and II

c. I and III

d. I, II, and III

2. What type of receptor is described in the followingparagraph?

Binding of a signaling molecule to this type of receptor uses anenzyme to remove a phosphate group from an ATP molecule to activateanother receptor. The activated receptor can be recognized by relayproteins inside the cell, which bind to the receptor and changeshape. These activated proteins then trigger a transduction pathwaythat leads to some sort of cellular response.

a. intracellular receptor

b. ligand-gated ion channel

c. g protein-coupled receptor

d. receptor tyrosine kinase

3. Yeast cells, plant cells, and mammal cells all share manysimilarities in cell signaling. This provides evidence that

a. cell-signaling mechanisms are only found in organisms that usemethods of sexual reproduction

b. intercellular communication evolved as a way for multicellularorganisms to coordinate cell functions

c. eukaryotic cells use signal transduction pathways whileprokaryotic cells use a more primitive form of signaling

d. signal transduction pathways appeared in cells before theevolution of multicellular organisms

limehornet465

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

BIOL 2021 Chapter Notes - Chapter 15.11: Cell Membrane, Membrane Transport Protein, Autocrine Signalling

Document Summary

Get access

Related Documents

BIOL 2021 Chapter Notes - Chapter 15: Autocrine Signalling, Paracrine Signalling, Extracellular Fluid

BIOL 2021 Lecture 11: Lecture 11 – Cell Signaling chapter 15.docx

BIOL 2021 Lecture Notes - Lecture 15: Gq Alpha Subunit, Autocrine Signalling, Arginine

Related Questions