BIO 1140 Lecture Notes - Signal Transduction, Cell Signaling, Plasmodesma

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erincod524

9 Jun 2014

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Cell to cell signalling lecture notes: the elements of a signalling system, types of cell communication. Gap junctions and plasmodesmata are direct communication sources. Chemical messengers chemicals that are synthesised by one cells and are used to affect the behaviour of other cells. Transduction: primary messenger binds to receptor and causes. Involves converting primary signal into a primary response: signalling pathway has to be terminated at the appropriate time. If the signalling pathway cannot be terminated then the cell is going to always respond to that signal continuously. Signalling molecule (first messenger: signalling cascades and second messengers, changes behaviour of the target cell. Response: changes in gene expression, changes in activities of enzymes, transcription factors or other regulatory proteins, transporters, cytoskeleton etc. The process of converting the signal (primary messenger) into a cellular response: provides three examples of cellular examples of cellular activities that can be altered in response to a signalling molecule.

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

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6. True or false

a_______ Nuclear pore complexes are specialized so that some mediate import and others mediate export

b_______ Membrane-bound and free ribosomes, which are structurally and functionally identical, differ only in the proteins they happen to be making at a particular time.

c_______ Some proteins can be made as either free or membrane-bound proteins. They have the same mRNA but different splicing and poly-adenylation patterns

d_______ a protein that does not have a sorting signal will be tagged for destruction by ubiquitin

e_______ when the hydrophobic signal peptide emerges from the ribosome, it is bound by SRP, which causes a pause in protein synthesis. Synthesis resumes when the ribosome with a bound SRP then binds to the SRP receptor on the cytosolic surface of the rough ER.

f________ A protein cannot leave the ER unless it is correctly folded

g________ All of the glycoproteins and glycolipids in intracellular membranes have their oligosaccharide chains facing the cytosolic side, and all those in the plasma membrane have their oligosaccharide chains facing the outside of the cell.

1. In order for a hormone to cause a response, it must first bindto an appropriate receptor on its target cell. (Points: 1)
True
False

2. Disorders associated with the endocrine system can be caused byproblems with hormone production or lack of receptors for thehormones on the target cells. (Points: 1)
True
False

3. The levels of potassium and sodium in the body are regulatedprimarily by the hormone aldosterone. (Points: 1)
True
False

4. Nitric oxide is produced by cells lining the blood vessels; thischemical messenger regulates the contraction of smooth muscle inthe digestive tract as well as local blood flow in various tissuesof the body. (Points: 1)
True
False

5. Uptake of blood glucose by liver cells is stimulated by (Points:1)
ADH
prolactin
parathyroid hormone
glucagon
insulin

6. Which of the following is true regarding estrogen andprogesterone? (Points: 1)
They are secreted by the ovaries.
They are released during a female's reproductive years.
They regulate the menstrual cycle.
They stimulate the development of female secondary sexcharacteristics.
all of the above

7. Which of the following is not a symptom of diabetes mellitus?(Points: 1)
blurred vision
high sodium concentration in the blood and urine
excessive thirst
tingling in the feet or hands
fatigue

8. Which of the following is required in the diet in order foractive thyroid hormones to be produced? (Points: 1)
calcium
phosphorus
iodine
zinc
iron

9. Which of the following nonhormonal chemical messengers isimportant in local control of blood flow and blood clotting?(Points: 1)
prostaglandins
nerve growth factor
tumor angiogenesis growth factor
histamine
epidermal growth factor

10. If diabetes is left untreated, which of the following coulddevelop as a result? (Points: 1)
neural disorders
kidney failure
blindness
cardiovascular disorders
all of the above

11. The process by which the blastocyst becomes buried within theendometrial lining of the uterus is: (Points: 1)
fertilization.
implantation.
morphogenesis.
differentiation
embryonic development.

12. The placenta forms from embryonic tissue and (Points: 1)
bone marrow
amniotic fluid
embryonic disk
endometrium
yolk sac

13. Which of the following organs is not fully developed in a fetusand is therefore bypassed by the ductus aerteriosus? (Points:1)
liver
pancreas
heart
lungs
bladder

14. During puberty, the secretion of GnRH causes the secretion of________, which in turn stimulate(s) the production of sexhormones. (Points: 1)
LH and FSH
oxytocin and prolactin
insulin
growth hormone
oxytocin and growth hormone

15. Research on the aging process shows that wounds of the elderlyheal more slowly and that they are more susceptible to disease.These are problems associated with an aging ________ system.(Points: 1)
respiratory
immune
integumentary
digestive
endocrine

________________________________________

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BIO 1140 Lecture Notes - Signal Transduction, Cell Signaling, Plasmodesma

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