BIO 110 Lecture Notes - Signal Transduction, Cyclic Adenosine Monophosphate, Growth Factor

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22 Feb 2013

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Local and long-distance signaling: cells communicate by chemical messengers. Ligand or signal molecule: cells have receptor proteins that ligands bind to. On cell membrane or inside the cell. Fits a specific ligand: when a ligand and receptor protein bind, a ___________ ___________ in the receptor protein is induced and a response in the cell is generated. How do cell"s communicate: local signaling, direct contact: Animal and plant cells have cell junctions that directly connect the cytoplasm of adjacent cells: gap junctions (animal cells, plasmodesmata (plant cells) Animal cells may also communicate by cell-cell. Recognition: ligand is bound to the membrane of another cell. Plasmodesmata between plant cells (a) cell junctions (b) cell-cell recognition. When animal cells do not come in direct contact with each other they communicate using local regulators, messenger molecules that travel only short distances. Paracrine signaling a cell acts on nearby target cells by secreting signal molecules into the extracellular fluid: circular perfume example.

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

The insulin receptor is a
a. phosphatase.
b. kinase.
c. phosphodiesterase.
d. cAMP molecule.
e. G protein.

What do the following receptors all have in common: G protein-linked receptors, protein kinases, and ion channels?
Select one:
a. Conformational change once the ligand is bound
b. Ligand binding
c. Amplification of the signal
d. All of the above

Diacylglycerol
Select one:
a. activates G proteins.
b. hydrolyzes phosphatidyl inositol-bisphosphate.
c. is released from the cell as a paracrine-signaling molecule.
d. opens Ca2+ channels.
e. activates protein kinase C

Gap junctions
Select one:
a. permit metabolic cooperation among linked cells.
b. are present on few copies per cell.
c. contain membrane lined bridges.
d. are channels about 1. 5 mm in diameter.
e. allow large molecules and ions to pass rapidly between cells.

Smooth muscle cells in the airways relax while those in the blood vessels contract in response to the hormone epinephrine. What would you expect to be different in these two types of cells exposed to epinephrine?
Select one:
a. Presence of epinephrine receptors.
b. Exposure to epinephrine released by neighboring cells.
c. Activation of protein kinases.
d. Rate of metabolism.
e. Types of proteins expressed.

The second messenger IP3
Select one:
a. is released from the cell as a paracrine-signaling molecule.
b. hydrolyzes phosphatidyl inositol-bisphosphate.
c. activates protein kinase C.
d. opens Ca2+ channels.
e. activates G proteins.

sangriaskunk539

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

BIO 110 Lecture Notes - Signal Transduction, Cyclic Adenosine Monophosphate, Growth Factor

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