BSC 114 Chapter Notes - Chapter 11: Apoptosis, Dephosphorylation, Phosphorylation

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graysardine594

24 Mar 2016

School

University of Alabama

Department

Biological Sciences

Course

BSC 114

Professor

Steven Marcus

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Document Summary

Signals received by cells are converted to specific cellular responses in a series of steps called signal transduction pathways. In many cases of local signaling, messenger molecules are secreted by the signaling cell and travel only short distances. Both animals and plants use chemicals called hormones for signaling. Hormones vary widely in molecular size and type, as do local regulators. The ability of a cell to respond is determined by whether it has a specific receptor molecule that can bind to the signaling molecule. The information conveyed by this binding must then be changed into another form (transduced) inside the cell before the cell can respond. The three stages of cell signaling: a preview. The process going on at the receiving end of a cellular conversation can be dissected into three stages: Response: reception- the target cell"s detection of a signaling molecule coming from outside the cell.

Related Questions

1. Be able to define the following terms: releasing hormone,inhibiting hornone, trooic hormone, nontropic hormones,neurosecretory cells.

2. What are hormones?

3. What are two specific differences between the endocrine andnervous systems?

4. What are the four different types of cell signaling?

5. What are the three types of hormonal control pathways? Givean example of each.

6. What is local regulator?

7. What type of feedback is a common feature of pathways thatcontrol homeostasis?

8. What are the three major classes of molecules that functionas hormones? Which are water-souble and which are lipid-souble?

9. Signaling by a hormone involves three key events. What arethey?

10. What is the correlation between solubility of a hormone andthe location of its receptors?

11. In addition to receptor location, water-soluble andlipid-soluble hormones also exhibit additional differences in theirresponse pathways. What are these differences?

12. What is signal transduction pathway?

13. Why can the same hormone have different effects on differentbody tissues?

14. Liver cells and the blood vessels of skeletal muscle cellshave identical surface receptors for epinephrine, yet the responeof these two cells types is dramatically different. Explain howthis is possible.

15. In the "fight or fight response" the release of epinephrinefrom the adrenal medulla cause skeletal muscle blood vessels todilate while simultaneously constricting blood vessels of theintestine. Explain how this is possible.

16. List the three types of local regulators discussed in classand explain their function.

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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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BSC 114 Chapter Notes - Chapter 11: Apoptosis, Dephosphorylation, Phosphorylation

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