BIOL 1201 Lecture Notes - Lecture 5: Myelin, Signal Transduction, Axon Hillock

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28 Nov 2016

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In a normal cell which of the following statements is correct: the membrane potential is negative. In a portal system how many capillary beds does the blood flow through as it travels from the heart back to the heart: 2. Two epsps decrease the membrane potential by 15mv each and one ipsp increases the membrane potential by with a 15mv. The amacrine cells are responsible for amplifying the stimulus energy: false, during sensory adaptation your response to a stimulus, decreases, the central nervous system (cns) consists of, the brain and spinal cord, the somatic division. During a muscle contraction the: false space between the z-lines will decrease, true. Class questions: when a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane a2. It in turn stimulates vascular spasms and attracts additional platelets to the injured site. Where would you expect to find the receptors for: assume there are 100 different cell-signaling compounds in you.

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

cerisehedgehog846

1/What is the fate of a protein with no N-terminus Signal Sequence?

(a)Transport through the constitutive secretory pathway

(b)Dispersal throughout the cytoplasm

(c)Transport into the nucleus

(d)Transport to the rough endoplasmic reticulum (RER)

2/ In nerve cells, Botulinum toxin-A degrades a subunit of a T-snare localized on the plasma membrane, how would this affect vesicular trafficking?

(a) It blocks the co-translational import of neurotransmitter proteins into the Endoplasmic reticulum via the translocon.

(b) It prevents the addition of carbohydrates to translated proteins

(c)It blocks the fusion of neurotransmitter-containing vesicles with the plasma membrane because theT-snare would not be able tophysically interact with the V-snare.

(d) None of the above

What is the correct order of events of Clathrin-mediated endocytosis?

1. Uncoating of Clathrin- coated vesicle

2. Recruitment of Clathrin and selection of cargo

3. Fusion of vesicle with early endosome

(a) 1, 2, 3

(b) 2, 1, 3

(d) 3, 1, 2

4/ Vesicles traveling anterogradely will eventually fuse with the cell membrane.

Which of the following elements does NOT participate in the fusion event?

(a) v-snare

(b) t-snare

(d) clathrin coat protein

When a cell releases a hormone into the bloodstream and a number of cells in a

distal location respond, this type of signaling is...

(a) Autocrine signaling

(b) Endocrine signaling

(d) Juxtacrine signaling

taupereindeer397

Cell Membranes Lab Report

Diffusion

Compare the following terms: solvent, solute, andsolution.

Go to Lab, Section I, Exercise 1 to explore the factorsinfluencing the rate of diffusion and complete the following:

Predict how molecular mass and temperature may affect theoutcome of this experiment.

Record the data from information in the Lab in the tablebelow.

Time (min)	Diameter (mm)
Time (min)	5Â°C MB	5Â°C PP	23Â°CMB	23Â°C PP
0
15
30
45

Construct a line graph of the data from the table above. Yourgraph should include labeled axes, units, and a legend indicatingwhich treatment is presented. Sign, date and prepare an image ofyour graph and include it with this lab report.

Osmosis

Go to Lab, Section II, Exercise 2 to view a demonstration ofosmosis and answer the following questions:

Describe the net movement of water in osmometer 1.

How is the movement of water molecules related to theconcentration gradient of the solution?

Go to Lab, Section II, Exercise 3 to observe the effect ofsolute concentration on the rate of osmosis. Answer the followingquestions:

Was the net movement of water in bags 1 to 4 into or out of thebags?

Explain the results from bags 4 and 5.

Selective Permeability of Membranes

Go to Lab, Section III, Exercise 4 to learn about theimportance of selectively permeable membranes, then complete thetable and answer the following questions:

	Contents of Beaker
	0 Min	30 Min
Starch
Chloride ion

Which substances diffused through the dialysis membrane?

How does dialysis tubing model the selective permeability of aplasma membrane?

Tonicity

Go to Lab, Section IV, Exercise 5 and 6 to observe plasmolysisin Elodea cells and tonicity in red blood cells. Summarizethe concept of tonicity using blood and Elodea cells asexamples. Your description should incorporate these terms: turgid,plasmolysis, hemolysis, and crenation.

Cells	Isotonic Solution	Hypertonic Solution	Hypotonic Solution
Elodea
RBC

Based on your previous work, reproduce the table below and drawan illustration of a single cell in each box. Include arrows toshow the direction of water flow relative to each cell and dots tosymbolize solutes. Sign, date and prepare an image of your drawingand include it with this lab report.

Cells	Isotonic Solution	Hypertonic Solution	Hypotonic Solution
Elodea
RBC

Summary Questions

Compare diffusion and osmosis. Give an example of each.

2. In which direction will osmosisoccur if a 15% sugar solution is separated from a 25% sugarsolution by a selectively permeable membrane?

3. Why did osmosis, but not diffusionof sucrose molecules, occur across the dialysis membrane containing20% sucrose solution?

4. You are having a party and thecelery is limp. What might you do to make the celery crisp (turgid)again? What will occur in the cells?

5. A small amount of fertilizer(mineral salts) will stimulate plant growth, but over fertilizationcan kill plants? Why?

6. Michael adds sugar to his coffee.Explain what in this drink is the solvent, solute, and solution.

7. You add a cube of sugar to yourdrink. How could you speed up the diffusion of sugar moleculeswithout stirring?

8. How is dynamic equilibriumestablished within a solution?

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BIOL 1201 Lecture Notes - Lecture 5: Myelin, Signal Transduction, Axon Hillock

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