BIO 211 Lecture Notes - Lecture 4: Autocrine Signalling, Paracrine Signalling, Bacterial Effector Protein

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amethystlouse762

23 Jan 2017

School

Drexel University

Department

Bioscience & Biotechnology

Course

BIO 211

Professor

Stanford Jennifer

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Document Summary

Cells must respond to changes: monitors intracellular and extracellular compartments. Eukaryotes communicate using extracellular signal molecules: receptor proteins-typically found on the cell surface to allow binding of a signal molecule. Intracellular signaling proteins- process signals inside of a receiving cell to send it to the appropriate targets. Effector proteins- the target that is usually altered by the incoming. Quorum sensing- the process by which bacteria can coordinate their behavior signal. Extracellular signals can act over long or short distances. Contact-dependent signaling- extracellular signal molecules that remain bound to the surface of the signal cell: only influences cells that come into contact with it. Important in development and immune responses: may effect large distances. Signaling cells that secrete molecules to send signals to the extracellular fluid. Local mediators- the secreted molecules that can typically only act on cells in that environment. Referred to as paracrine signaling: often times the signal cell and target cell are different cell types.

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

Second messengers play an important role in cellcommunication.

Which of the following best describes their role?

		None
		integrate, amplify and distribute messages throughout thecell
		Release messages to other cells?
		Receive information at the cell surface

What is true of disulfide bonds?

	a.	They often occur in the cytosol
	b.	They are a noncovalent bond
	c.	They are formed enzymatically in the ER
	d.	They act as reducing agents
	e.	they increase protein flexibility

Which of the following is NOT an example of a cell communicationmolecule?

		nucleases
		nitric oxide
		hormones
		kinases

What is true of binding pockets?

	a.	They only occur in the membrane
	b.	They occur in unfolded proteins
	c.	They contain electrostatic interactions
	d.	They contain variable amino acids
	e.

What is true of cell signaling?

	a.	Extracellular signals transduced by rectors always alter cellbehavior very quickly
	b.	Some cells require cell signals just to survive
	c.	Cell signals can be interpreted differently by differentcells
	d.	B and C only
	e.	All of the above (A, B and C)

Histone tails can be modified to change the shape and"tightness" of the nucleosomes. Acetylated histones result in whicheffect?

		Open DNA
		increased transcription
		closed DNA
		decreased transcription
		1+2
		1+4
		3+4
		2+3

Shifting the two bound tRNA from the A and P sites to the E andP sites of the ribosome involves:

	a.	The movement of the small ribosome subunit down the mRNAchain
	b.	The degradation of the A site on ribosome
	c.	The synthesis of the E site on the ribosome
	d.	The movement of the large subunit relative to the smallsubunit
	e.	All of the above

Intracellular signaling pathways are awesome! What is the onething they can NOT do?

	a.	relay the signal, to spread it through the cell
	b.	nothing, they can communicate any cellular need
	c.	distribute the signal to more than one effector protein
	d.	integrate the signal from more than one cellular pathway
	e.	Amplify the signal received, making the signal stronger

Specificity of protein/protein and protein/DNA binding isdetermined by what?

		Non-covalent bonds
		Hydrophobic interactions
		Covalent bonds
		shape of the binding site
		all of the above
		none of the above
		1,2,3
		1,2,4
		1,3,4

The coiling structure of the DNA into chromosomes is achieved bywhat?

		alpha helix
		beta pleated sheets
		chaperone proteins
		DNA/Protein complexing

Which regions (s) of the DNA are found in the final protein?

	a.	poly-A tail
	b.	A and B
	c.	Exons
	d.	UTRs
	e.	Introns

Metabolic processes can be turned "on" and "off" by chemicalmodifcation.

Which chemical modification do we associate with changing theactivity of an enzyme in a transient/non-permanent manner?

		Phosphorylation
		Ubiquitination
		Methylation
		Acetylation

DNA hybridization involves attaching a florescent dye towhat?

	a.	Antibody
	b.	Nuclear stain
	c.	Probe DNA
	d.	tRNA
	e.	rRNA

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BIO 211 Lecture Notes - Lecture 4: Autocrine Signalling, Paracrine Signalling, Bacterial Effector Protein

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