BI110 Chapter Notes - Chapter Module 21: Threonine, Hormone Response Element, Repressor

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2 Jun 2017

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A: the diffusion of water through a selectively permeable membrane cell"s plasma membrane. A: signals arrive in a chemical message but energy from the environment (heat and light) can also activate receptors. A: a sequence of biochemical reactions and events beginning with an environmental or chemical signal interacting with a cell and ending with a physiological response by that cell. They involve proteins (signal transmission or cell response) A: it usually binds to a protein receptor embedded in the membrane; however a few chemical signals such as steroid hormones, bind to their receptors inside the cell. A: when activated, it activates second messengers that transmit the signal further. A: a single molecule can activate many responses; therefore it can amplify the original stimulus as the signal is transmitted. Q: how does a cell change the functionality of a protein? (turn on/off) A: phosphorylation is the most common method (requires energy- bonds atp)

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

33 Different glycoproteins can have a diverse array of oligosaccharides. Which of the statements below for making glycoproteins on plasma membrane is true?

(a) Extensive modification of oligosaccharides occurs in the extracellular space.

(b) Initial oligosaccharide chains are made by addition of one sugar at a time onto the protein in the ER lumen.

(c) Each layer of Golgi membrane structures contains identical modification enzymes for modifying sugar chain on proteins.

(d) ER lipids can be modified by sugar chain, which can be used for sugar chain modification of the proteins.

34 In a multicellular organism, when a signal needs to be sent to most cells the signal most suited for this is a ___________.

(a) neurotransmitter.

(b) hormone.

(d) plasma membrane anchored ligands.

35 Typically, members of the steroid hormone receptor family __________________.

(a) are cell-surface receptors.

(b) do not undergo conformational changes by binding to their ligands.

(d) interact with signal molecules that diffuse through the plasma membrane

36 Which of the following statements about what happens when a G-protein-coupled receptor activates a hetero trimeric G protein is true?

(a) The Î² subunit exchanges its bound GDP for GTP.

(b) The GDP bound to the Î± subunit is phosphorylated to form bound GTP.

(d) It activates the Î± subunit and inactivates the Î²Î³ complex

37 Which of the following statements about signal transduction is false

(a) Ca2+ concentration in cytosol will increase when PLC (Phospholipase C) is activated by signal.

(b) Cyclic GMP is made in smooth muscle cells when they received NO signal.

(d) Ligand binding to RTK activates its enzyme activity then the activated RTK phosphorylates tyrosine residues on itself.

greywoodchuck816

1. Hormones are chemical signals that
A.
affect adjacent cells.
B.
work in prokaryotes.
C.
are autocrine signals.
D.
travel through circulatory systems.
E.
are paracrine signals.

Answer choice C

2. A universal feature of receptors is that they
A.
undergo structural (shape) changes when the signal molecule isbound.
B.
are protein kinases.
C.
are present in the plasma membrane.
D.
are ion channel proteins.
E.
do not undergo structural (shape) changes when the signal moleculeis bound.

Answer choice A

3. Which of the following statements about receptors and enzymes istrue?
A.
Most receptors and enzymes are nucleic acids.
B.
Both receptors and enzymes may be integral membrane proteins.
C.
Receptor ligands, like enzyme substrates, are altered during signaltransduction.
D.
Both receptors and enzymes are not specific for the molecules theybind.
E.
Receptors generally have enzymatic activity, whereas enzymes donot.

Answer choice B

4. Chemical signal transduction pathways
A.
use non-specific receptors.
B.
involve binding of the signal molecule to receptors.
C.
use receptors that are located only on the plasma membrane.
D.
use receptors that change the ligands they bind.
E.
all use G proteins.

Answer C

5. Adenylyl cyclase
A.
is located such that cAMP is made outside of cells.
B.
makes cAMP from ATP with the liberation of phosphate (Pi).
C.
is inactivated by activated G proteins.
D.
makes cAMP from ATP with the liberation of pyrophosphate(PPi).
E.
is directly activated by receptors.

Answer choice D

6. Which of the following statements is true?
A.
Glycogen phosphorylase in liver cells is always active.
B.
cAMP is referred to as a âfirst messenger.â
C.
Epinephrine directly activates adenylyl cyclase.
D.
cAMP is referred to as a âsecond messenger.â
E.
Adenylyl cyclase is a protein kinase.

Answer choice C

7. Which step of the signal transduction cascade that results inglucose release during the âfight-or-flightâ response does notdirectly involve a nucleotide?
A.
Phosphorylation of glycogen phosphorylase
B.
Activation of adenylyl cyclase
C.
Epinephrine binding to its receptor
D.
Activation of a G protein
E.
Inactivation of glycogen synthase

Answer choice A

8. The phosphorylation of proteins by ATP
A.
is catalyzed by enzymes known as âprotein kinases.â
B.
always stimulates the activity of an enzyme.
C.
is catalyzed by adenylyl cyclase.
D.
is catalyzed by the epinephrine receptor.
E.
is catalyzed by G proteins.

Answer choice A

9. Suppose the concentration of epinephrine in the blood stream ofan animal drops. The cyclic AMP concentration in liver cells wouldbe expected to _______ because _______ activity would_______.
A.
increase; adenylyl cyclase; increase
B.
decrease; protein kinase; decrease
C.
decrease; phoshodiesterase; decrease
D.
increase; protein kinase; increase
E.
decrease; adenylyl cyclase; decrease

Answer choice B

BI110 Chapter Notes - Chapter Module 21: Threonine, Hormone Response Element, Repressor

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