NUTR641_MOD_8_Quiz8__Basic_Concepts_of_Cellular_Transport_and_Signaling

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

https://canvas.liberty.edu/courses/318794/quizzes/1674764

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Score for this attempt: 70 out of 80 *

Submitted Oct 11 at 1:47am

This attempt took 78 minutes.

2 / 2 pts

Question 1

Phosphorylation of a tyrosine in the cyclin-dependent kinases (CDK)

inactivates the protein by:

inhibiting the binding of cyclin.

inhibiting the binding of ATP.

Correct!

inhibiting the binding of the "T loop".

preventing dissociation of the CDK/cyclin complex.

2 / 2 pts

Question 2

Peripheral membrane proteins:

are generally noncovalently bound to membrane lipids.

Correct!

are usually denatured when released from membranes.

can be released from membranes only by treatment with

detergent(s).

may have functional units on both sides of the membrane.

penetrate deeply into the lipid bilayer.

2 / 2 pts

Question 3

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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What kind of bond can link a prenyl anchor to a polypeptide?

an ester bond to an internal serine

an amide bond to a glycine

a thioester to a cysteine

an ester bond to the C-terminus

a thioether bond to a cysteine side chain

Correct!

2 / 2 pts

Question 4

Which statement is TRUE concerning the chloride-bicarbonate

exchanger?

This transporter is electrogenic.

The exchanger is a passive antiporter.

This protein is involved in carbon dioxide transport in the blood

stream.

The exchanger is a passive antiporter, and this protein is

involved in carbon dioxide transport in the blood stream.

Correct!

This transporter is electrogenic, and the exchanger is a passive

antiporter.

2 / 2 pts

Question 5

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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G protein–coupled activation of phospholipase C directly generates

which second messenger?

diacylglycerol

inositol-1,4,5-trisphosphate

calcium

both diacylglycerol and inositol-1,4,5-trisphosphate

Correct!

both inositol-1,4,5-trisphosphate and calcium

2 / 2 pts

Question 6

The ion channel that opens in response to acetylcholine is an example of

a _____ signal transduction system.

G-protein

ligand-gated

Correct!

receptor-enzyme

serpentine receptor

voltage-gated

2 / 2 pts

Question 7

Which step is NOT involved in neurotransmitter release at a synapse?

creation of a fusion pore

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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hemifusion induced by zipping and lateral tension on the

bilayers

v-SNARE binding to t-SNARE

pore widening and release of neurotransmitter

flippase-mediated movement of phosphatidylserine from the

inner to the outer leaflet

Correct!

2 / 2 pts

Question 8

Facilitated diffusion through a biological membrane is:

driven by a difference of solute concentration.

Correct!

driven by ATP.

endergonic.

generally irreversible.

not specific with respect to the substrate

2 / 2 pts

Question 9

The G protein involved in visual signal transduction is:

a leukotriene.

transducin.

Correct!

arrestin.

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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rhodopsin.

a GTP receptor.

2 / 2 pts

Question 10

Hormone-activated phospholipase C can convert phosphatidylinositol

4,5-bisphosphate to:

diacylglycerol + inositol triphosphate.

Correct!

diacylglycerol + inositol+ phosphate.

glycerol + inositol + phosphate.

glycerol + phosphoserine.

phosphatidyl glycerol + inositol + phosphate.

2 / 2 pts

Question 11

Ubiquitin is a:

component of the electron transport system.

protease.

protein kinase.

protein phosphorylase.

protein that tags another protein for proteolysis.

Correct!

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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2 / 2 pts

Question 12

The specificity of signaling pathways does NOT include:

flippase-catalyzed movement of phospholipids from the inner to

the outer leaflet.

Correct!

migration of signal proteins into membrane rafts.

phosphorylation of target proteins at Ser, Thr, or Tyr residues.

the ability to be switched off instantly by hydrolysis of a single

phosphate-ester bond.

the assembly of large multiprotein complexes.

2 / 2 pts

Question 13

Oncogenes that encode _____ are NOT known.

cytoplasmic G proteins and protein kinases

DNA-dependent RNA polymerases

Correct!

growth factors

secreted proteins

transmembrane protein receptors

2 / 2 pts

Question 14

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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FRAP experiments are generally used in membrane studies to examine:

transverse diffusion rates.

active transport rates.

lateral diffusion rates.

Correct!

both transverse diffusion rates and active transport rates.

both transverse diffusion rates and lateral diffusion rates.

2 / 2 pts

Question 15

Why is estrogen associated with carrier proteins in the blood?

Carrier proteins are necessary to import estrogen into cells.

Estrogen has only limited solubility in the bloodstream.

Correct!

Estrogen is very unstable in the blood.

The carrier proteins bind with estrogen to receptors.

2 / 2 pts

Question 16

Which statement concerning cyclin-dependent protein kinases is NOT

correct?

Each type of cell contains one specific form (isozyme).

Correct!

Their activity fluctuates during the cell cycle.

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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Their activity is regulated by changes in gene expression,

protein phosphorylation, and proteolysis.

Their activity is regulated by cyclins.

They can alter the activity of proteins involved in the

progression of cells through the cell cycle.

2 / 2 pts

Question 17

Which statement is TRUE for passive transport across a biological

membrane?

Passive transport is driven by a solute electrochemical gradient.

Correct!

Passive transport is driven by ATP.

Passive transport is irreversible.

Passive transport is driven by both a solute electrochemical

gradient ATP.

Passive transport is driven by a solute electrochemical gradient

and is irreversible.

2 / 2 pts

Question 18

The specificity of the potassium channel for K over Na is mainly the

result of the:

+ +

differential interaction with the selectivity filter protein.

Correct!

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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hydrophobicity of the channel.

phospholipid composition of the channel.

presence of carbohydrates in the channel.

presence of cholesterol in the channel.

2 / 2 pts

Question 19

Which feature of signal-transduction comes from high structural and

chemical complementarity between a signal molecule and its receptor?

specificity

Correct!

cooperativity

amplification

desensitization

integration

2 / 2 pts

Question 20

Which signaling mechanism is used most predominantly in plants?

cyclic-nucleotide dependent protein kinases

DNA-binding nuclear steroid receptors

G protein–coupled receptors

protein serine/threonine kinases

Correct!

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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protein tyrosine kinases

2 / 2 pts

Question 21

The effects of acetylcholine on the postsynaptic ion channel are mainly

due to:

cyclic nucleotide synthesis.

protein cleavage (proteolysis).

protein conformational changes.

Correct!

protein phosphorylation.

protein synthesis.

2 / 2 pts

Question 22

Calmodulin is a(n):

allosteric activator of calcium-dependent enzymes.

allosteric inhibitor of calcium-dependent enzymes.

calcium-dependent enzyme.

cell surface calcium receptor.

regulatory subunit of calcium-dependent enzymes.

Correct!

2 / 2 pts

Question 23

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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After membrane depolarization in neurons, export of potassium:

makes the value of V more negative.

decreases the concentration gradient for potassium.

is energetically favourable.

All of the answers are correct.

Correct!

None of the answers is correct.

2 / 2 pts

Question 24

Which statement is TRUE regarding lipid anchors?

Palmitoylations and prenylations both occur via thioester

linkages.

GPI anchors and prenylations are both attached to the C-

terminal end of the mature protein.

Correct!

Myristoylations and palmitoylations are both reversible

modifications.

Prenylations occur exclusively on the outside leaflet of the

plasma membrane.

2 / 2 pts

Question 25

Mutations are NOT part of the progression from normal to cancerous

cells in colorectal cancer in:

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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Abl involved in cellular signaling.

Correct!

KRAS and BRAF kinases involved in cellular signaling.

PI3K and PTEN involved in cellular signaling.

MMR involved in DNA repair.

CDC4 involved in ubiquitination.

2 / 2 pts

Question 26

Which statement is TRUE of gated ion channels?

Each channel can allow 10 million ions per second through the

membrane.

Correct!

The gating mechanism involves piston-like movement of the

transmembrane helices.

Each channel lets both positive and negative ions flow through

the pore.

Closing of the gate requires phosphorylation of the channel

protein.

Gated channels only respond to intracellular ligands.

2 / 2 pts

Question 27

Why are hydropathy plots NOT usually used to detect transmembrane

strands in porins?

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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The length of a transmembrane strand is typically shorter

than that of an helix.

Amino acids in transmembrane strands in porins may not be

exclusively hydrophobic.

Amino acid side chains project away from the polypeptide in a

sheet

Answers A and B are both correct.

Correct!

All of the answers are correct.

2 / 2 pts

Question 28

An electrogenic Na transporter:

catalyzes facilitated diffusion of Na from a region of high

Na concentration to one of lower Na concentration.

+ +

must catalyze an electron transfer (oxidation-reduction) reaction

simultaneously with Na transport.

must transport both Na and a counterion (Cl , for example).

+ –

transports Na against its concentration gradient.

transports Na without concurrent transport of any other

charged species.

Correct!

2 / 2 pts

Question 29

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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14/18

Choline-containing lipids are enriched in the outer leaflet of erythrocyte

plasma membranes. This includes:

cardiolipin.

phosphatidylinositol.

sphingomyelin.

phosphatidylcholine.

both sphingomyelin and phosphatidylcholine.

Correct!

2 / 2 pts

Question 30

ABC transporters are NOT known to facilitate moving:

cancer drugs out of cancer cells.

antibiotics out of bacteria.

membrane lipids from the inner leaflet to the outer leaflet.

chloride ions in the lung.

vitamin E into lipocytes.

Correct!

2 / 2 pts

Question 31

Scatchard analysis can provide information on:

enzyme cascades.

enzyme mechanisms.

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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gated ion channels.

protein phosphorylation.

receptor-ligand interactions.

Correct!

2 / 2 pts

Question 32

Which statement concerning cyclins is NOT correct?

They are activated and degraded during the cell cycle.

They are regulatory subunits for enzymes that catalyze the

phosphorylation of proteins.

They can become linked to ubiquitin.

They catalyze the phosphorylation of proteins.

Correct!

They contain specific amino acid sequences that target them for

proteolysis.

2 / 2 pts

Question 33

Which factor is NOT a shared feature of signaling by mammalian vision

and gustatory receptor pathways?

changes in cAMP levels

Correct!

GDP/GTP exchange

heterotrimeric G proteins

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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open/closing of ion channels

transmembrane receptors

2 / 2 pts

Question 34

In kidneys, what is the response when the atrial natriuretic factor (ANF)

binds to its receptor?

increased cAMP concentration in the cytosol

activation of protein kinase G (PKG)

stimulation of water and sodium excretion

Correct!

both increased cAMP concentration in the cytosol and

stimulation of water and sodium excretion

both increased cAMP concentration in the cytosol and

activation of protein kinase G (PKG)

2 / 2 pts

Question 35

Protein kinase A (PKA) is:

activated by covalent binding of cyclic AMP.

affected by cyclic AMP only under unusual circumstances.

allosterically activated by cyclic AMP.

Correct!

competitively inhibited by cyclic AMP.

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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noncompetitively inhibited by cyclic AMP.

Not yet graded / 5 pts

Question 36

Your Answer:

Describe the role of G proteins in olfactory sensory transduction

A sensory stimulant (like the smell of rain) interacts with the receptor, thus

triggering a conformational change. This change can ultimately result in

displacement of bound GDP by GTP on the G protein. This G protein is

now activated which activates either adenylyl cyclase or phospholipase C.

This stimulates the liganads opening the ion channels

Not yet graded / 5 pts

Question 37

Your Answer:

Distinguish between simple diffusion (SD), facilitated diffusion (FD),

and active transport (AT) across a membrane for the following questions.

(More than one may be true.)

(a) Which processes are energy dependent?

(b) Which processes need some kind of carrier protein(s)?

(d) Which processes can establish a concentration gradient?

(e) How much energy does it take to transport an uncharged substrate in,

if its starting inside concentration is 10-fold greater than outside?

Simple and facilitated diffusion are both passive and movement is along

the concentration gradient. Simple diffusion occurs from higher

concentration to lower concentration, making it energy independent.

A.) AT is energy dependent

B.) FD requires specific carriers (going in the opposite direction so carrier

protein is required.

C.) AT can be saturated by substrate

D.) AT can establish a concentration gradient (all forms require

concentration gradient to occur.

E.) -5704.82 J/mol

10/11/22, 1:49 AM

Quiz: Basic Concepts of Cellular Transport and Signaling: NUTR641: Nutritional Biochemistry I (B01)

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Quiz Score: 70 out of 80

NUTR641_MOD_8_Quiz8__Basic_Concepts_of_Cellular_Transport_and_Signaling

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