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MCDB 310 > Exam 2 Problem Roulette > Flashcards

Exam 2 Problem Roulette Flashcards

1
Q

Two sugars that differ only in their configuration about a single carbon atom are called?

A

Epimers

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2
Q

Which of the following bonds links the monosaccharides in amylose, causing this molecule to naturally form a coil?

A

Alpha 1 ->4

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3
Q

What is a lectin?

A

Proteins that bind specific carbohydrates

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4
Q

What describes a glycoprotein?

A

A transmembrane protein that is covalently linked to a unique series of carbohydrates that specifies the cell type

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5
Q

Which of the following are true about the reactions between monosaccharides and larger polysaccharides?

During starch synthesis, additional monosaccharides are added to amylose via a oxidative reduction reaction

Disaccharide formation proceeds via a condensation reaction that liberates water

A non-reducing sugar has no anomeric carbon available to react

In a glucose disaccharide, the reducing sugar exists in a stable anomeric configuration

Both amylose and amylopectin tend to adopt a coiled tertiary structure

The main factor that contributes to the stability of chitin is the acetylated amino group

A

-Disaccharide formation proceeds via a condensation reaction that liberates water
-A non-reducing sugar has no anomeric carbon available to react
-Both amylose and amylopectin tend to a adopt a coiled tertiary structure

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6
Q

Which molecule below is not a glycoconjugate

Heparan Sulfate

Lipopolysaccharides

Hyaluronate

DNA

Integrins

A

DNA

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7
Q

What statement about the position of the oxygen atom attached to C5 in monomeric Alpha-D-glucose is correct?

The C5 oxygen is on the same face of the ring as the C6 carbon.

The C5 oxygen is on the opposite face of the ring as the C6 carbon.

None of the other choices is correct

The C5 oxygen is part of an acetal functional group

The C5 oxygen is part of a hemiacetal functional group

A

The C5 oxygen is part of a hemiacetal functional group

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8
Q

Which of the following does NOT describe a general function of carbohydrates?

Metabolic energy source in biological systems.

Post-translational modifications of extra-cellular proteins.

Signaling hormone

Structural component of bacterial cell walls.

Headgroup component of certain membrane lipids.

A

Signaling hormone

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9
Q

Which of the following about cellulose and chitin is FALSE?

The strands stack very tightly, excluding the absorption of water

They are both linear homopolymers

They contain the same kind of glycosidic linkages

The higher order structures for both exclusively comprises parallel strands

A

The higher order structures for both exclusively comprises parallel strands

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10
Q

In which of the following locations would you expect to find a high concentration of peptidoglycans?

In starch granules

In the extracellular matrix

In the hard exoskeletons of certain insects

In eukaryotic cell membranes

In gram-positive bacterial cell walls

A

In gram-positive bacterial cell walls

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11
Q

Proteoglycans, Glycoproteins, and Glycolipids are collectively known as which of the following?

Glycans

Peptidoglycans

Dextrans

Glycoconjugates

Glycosaminoglycans

A

Glycoconjugates

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12
Q

Which of the following Weak Interactions is most important or most influential for homopolysaccharide folding?

Van der Waal’s interactions

Hydrophobic interactions

Hydrogen Bonding

Ionic interactions

A

Hydrogen Bonding

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13
Q

Which statement about glycogen is FALSE?

Glycogen is a linear storage molecule used by mammals

Glycogen contains (α1→6) linkages

Glycogen contains (α1→4) linkages

Glycogen is a homopolymer of glucose

Glycogen has many non-reducing ends for each reducing end

A

Glycogen is a linear storage molecule used by mammals

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14
Q

When two monosaccharides join to form a disaccharide which of the following is true?

An anhydride is converted to a hydride.

A water molecule is released as an additional product for this reaction.

An acetal is converted to an hemiacetal.

The resulting disaccharide is not a reducing sugar.

The resulting disaccharide is a reducing sugar.

A

A water molecule is released as an additional product for this reaction.

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15
Q

Some sugars, such as glucose, which can reduce metals such as iron or copper are called:

Metalloglycosides

Anomeric Sugars

Glycans

None of the above

Reducing Sugars

A

Reducing Sugars

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16
Q

An aldohexose that forms a five-membered ring is then called which of the following?

A glucopyranose

A pyranose

An aldopentose

A furanose

A

A furanose

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17
Q

Which of the following does NOT describe a lectin?

A toxin that reversibly binds to complex carbohydrates on the surface of eukaryotic cells

A plant protein with that specifically binds a fungal glycoconjugate

Viral proteins that adhere to sialic acid on the host cell surface

A protein that interacts with the extracellular matrix by hydrogen bonding to specific glycans

A polytopic membrane protein with N-linked glycosylation

A

A polytopic membrane protein with N-linked glycosylation

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18
Q

Starch and Cellulose are two of the most abundant polysaccharides in nature. They are both composed of glucose subunits, but with very different structures. Which linkage(s) below is/are present in Starch?

α1 →4 linkages

α1 →6 branches

β1ž→4 linkages

A and B only

B and C only

A

A and B only

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19
Q

From the abbreviated name of the compound Gal(alpha1->1beta)Glc, Which of the following is NOT true? (Gal = galactose, Glc = glucose)

the glucose residue is the beta anomer.

two anomeric carbons were linked to form this compound

the compound is a reducing sugar

there are no hemiacetal groups in this compound

C-1 of glucose is joined to C-1 of galactose by a glycosidic bond.

A

the compound is a reducing sugar

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20
Q

What term refers to the interconversion of the alpha and beta anomers of glucose in solution?

Mutarotation

Oxidation/Reduction

Glycosidation

Epimerization

Racemization

A

Mutarotation

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21
Q

Which of the following is a purine linked to a phosphate group and a sugar?

Thymidine

Cyclic 3’,5’-cytosine phosphate

Deoxycytidine

Deoxyguanylate

Uridine

A

Deoxyguanylate

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22
Q

Which of the following does NOT contribute favorably to the energetics of forming a DNA double helix?

Hydrogen bonds between pairs of nitrogenous bases

Ionic interactions involving the phosphoribose backbone

van der Waals interactions between stacked bases

Cooperativity of the two strands annealing

Bases are hydrophobic relative to the phosphoribose backbone

A

Ionic interactions involving the phosphoribose backbone

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23
Q

Which of the following describes a general biological function of nucleotides?

Donor of phoshoryl groups (phosphates) for post-translation protein modification (including regulation).

Component of many important enzyme cofactors

Building block of DNA and RNA

General energy-carrying molecule in biological systems

All these answers are functions of nucleotides.

A

All these answers are functions of nucleotides.

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24
Q

Which of the following structures is NOT a permanent change to chromosomal DNA?

Denaturation

Mutation

Thymine-Thymine (cyclobutane) dimer

Deamination

Depurination

A

Denaturation

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25
Q

DNA hairpins located exactly opposite each other and on different strands of DNA are called which of the following?

H-DNA

Inverted repeat

Palindrome

Cruciform

Mirror repeat

A

Cruciform

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26
Q

Which of the following is primarily responsible for holding the two DNA strands together in a helix?

Disulfide linkages

Hydrophobic interactions

Phosphodiester bonds

Hydrogen bonds

Glycosidic linkages

A

Hydrogen bonds

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27
Q

Which of the following is on the 3’ end of a DNA sequence?

Amino group

Carboxyl of a sugar

Hydroxyl of a sugar

Phosphate

Base

A

Hydroxyl of a sugar

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28
Q

Which of the following is NOT an example of DNA damage?

Cytosine deamination

Thymidine dimer formation

Guanosine depurination

Cytosine methylation

A

Cytosine methylation

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29
Q

Which of the following are most likely to lead to triplex DNA?

Cytosine deamination

Wobble base pairing

Low pH causing cytosine protonation

Palindromic sequences

High guanosine content

A

Low pH causing cytosine protonation

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30
Q

Which of the following is FALSE about phosphodiester linkages?

They join the 3’ hydroxyl of one nucleotide to the 5’ hydroxyl of the next.

They are more stable in RNA than in DNA

They form the backbone of double helical structure.

They are present in both DNA and RNA

They are negatively charged at neutral pH

A

They are more stable in RNA than in DNA

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31
Q

Nucleic acids are characterized by which of the following?

Ring resonance that causes absorption of light near 260 nm

Formation of helices by DNA but not by RNA

A-T rich regions melting at higher temperatures than G-C rich regions

Formation of a hairpin by a Palindrome on two strands

Sugar and phosphate residues located near the center of the molecule after refolding in aqueous media

A

Ring resonance that causes absorption of light near 260 nm

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32
Q

Which of the following is on the 5’ end of a DNA sequence?

Carboxyl of a sugar

Base

Amino group

Hydroxyl of a sugar

Phosphate

A

Phosphate

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33
Q

Which of the following is NOT a common feature of DNA binding proteins?

alpha helices fit perfectly in the major groove

DNA binding proteins can recognize specific DNA sequences that are visible within the major groove

Slide along the DNA until they find the correct binding site

Preferentially recognize single-stranded DNA

Tend to have a lot of arginines and lysines

A

Preferentially recognize single-stranded DNA

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34
Q

Which statement is FALSE?

Different fragments of DNA would be expected to have different melting temperatures

Depurination and deamination are non-enzymatic mutations

RNA and DNA both form Hairpin structures and double-helices

Partially denatured DNA could have G-C rich regions that have broken Hydrogen bonds while the A-T regions are intact

All of the statements above are TRUE

A

Partially denatured DNA could have G-C rich regions that have broken Hydrogen bonds while the A-T regions are intact

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35
Q

Which of the following statements about nucleic acid double-helices is FALSE?

RNA and DNA adopt essentially identical structures.

G-C base pairs are more stable than A-T base pairs.

Bases are stabilized in part by aromatic (pi-pi) stacking.

The major groove is large enough to accommodate protein secondary structure elements.

Negatively charge phosphates are solvent exposed on the outsides of the helix.

A

RNA and DNA adopt essentially identical structures.

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36
Q

Which of the following is NOT consistent with the Watson-Crick model for the DNA double helix?

Base stacking helps stabilize the double helix

The two strands run antiparallel to one another.

The composition of bases obeys Chargaff’s rules

Guanosine residues can form tetraplex structure.

The sequence of one strand provides a template for duplication of the second strand

A

Guanosine residues can form tetraplex structure.

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37
Q

You perform a Sanger sequencing reaction. The template strand is:

5’ ATCGAAC 3’

However, you make a mistake and forget to add any dGTP. What is the most likely outcome?

You will get a single band representing a 3-nucleotide product in the G lane.

You will get a single band representing a 7-nucleotide product in the G lane.

You will get two bands representing 1- and 5-nucleotide products in the G lane.

You will get a single band representing a 1-nucleotide product in the G lane.

You will get no bands in the G lane.

A

You will get a single band representing a 1-nucleotide product in the G lane.

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38
Q

Consider the following two segments of RNA. Which of the following describes a secondary structure that is likely to be formed?

5’ AUCGCG 3’

5’ CGCAGAU 3’

Bulge

These two segments are not expected to form base pair interactions

B-form double helix

Hairpin

Cruciform

A

Bulge

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39
Q

Which statement about transcription factor binding to its cognate DNA target is likely true?

The minor groove of non-distorted DNA can easily accommodate an alpha-helix for sequence recognition.

The transcription factor likely has a significant, positively charged region in its surface which can bind DNA in a NON sequence specific manner.

Charge-charge interactions directly between Asp/Glu residues and the phosphate backbone likely contribute to protein-DNA interactions.

Recognition of the base pairs by amino acids such as Leu/Ile likely contributes to binding at the correct sequence

A

The transcription factor likely has a significant, positively charged region in its surface which can bind DNA in a NON sequence specific manner.

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40
Q

What bonds are broken in order to partially Denature double-stranded DNA?

Hydrophobic

Didulfide

Glycosidic

Phosphodiester

Hydrogen

A

Hydrogen

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41
Q

Which of the following is NOT an example of RNA secondary structure?

Hairpin

Internal Loop

Palindrome

Cruciform

Bulge

A

Palindrome

42
Q

Which weak interaction is most important in maintaining DNA as a double-helix?

Hydrogen bonds

Van der Waal’s interactions

Ionic interactions

Phosphodiester linkages

Hydrophobic interactions

A

Hydrogen bonds

43
Q

Which of the following is a covalent bond that links elements of the DNA “backbone”?

Phosphodiester

Ether

Peptide

Glycosidic

Hydrogen

A

Phosphodiester

44
Q

What parts of DNA are considered the “backbone”?

Nucleoside base

Sugar

Phosphate

A and B

B and C

A

B and C

45
Q

Movement of water across membranes is facilitated by proteins called _____________, movement of water is allowed by ____________ amino acids in the pore, and selectivity is enforced by the presence of _____________ amino acids at the selectivity filter.

hydropermeases, polar, basic

annexins, polar, acidic

aquaporins, polar, basic

aquaporins, polar, acidic

aquaporins, hydrophobic, basic

A

aquaporins, polar, basic

46
Q

Which of the following principles is consistent with the physical properties of membranes?

Lipids in membranes generally move freely (fluidly), both laterally and across the membrane

Peripheral proteins associate non-covalently with the polar head groups of lipids

Integral proteins span the membrane and associate with only the acyl chains of phospholipids, which stabilizes the proteins in a hydrophobic environment

Proteins in membranes are spaced symmetrically between the two layers of the bilayer, but in a manner that varies between membrane types

A

Peripheral proteins associate non-covalently with the polar head groups of lipids

47
Q

Which of the following is FALSE concerning the lipids in membranes?

Since white blood cells and red blood cells are exposed to essentially the same environment, their membranes would have the same lipid constituents in the same relative proportions. Function, not location.

The inner leaflet and the outer leaflet of plasma membranes both contain phospholipids

Carbohydrate groups of glycolipids always face the extracellular surface of the plasma membrane

Flipases can alter the distribution of lipids on the outer versus inner membrane leaflets

A

Since white blood cells and red blood cells are exposed to essentially the same environment, their membranes would have the same lipid constituents in the same relative proportions. Function, not location.

48
Q

Which factor(s) affect the direction in which an ion moves through an ion channel in a membrane?

I. the concentration differential across the membrane

II. the size and shape of the channel

III. the ion selectivity of the channel.

IV. the voltage differential across the membrane

II and III

I and IV

I and II

All of these

I, III and IV

A

I and IV

49
Q

Which small molecule is NOT made during an amplification process in cell signaling?

diacylglycerol (DAG)

cAMP

Inositol 1,4,5-trisphosphate (IP3)

cGTP

Steroid hormone

A

Steroid hormone

50
Q

Which of the following proteins that we discussed in class can be studied using patch clamp electrophysiology:

Aquaporin

GPCR

ABC transporter

GLUT1

CFTR

A

CFTR

51
Q

Which of the following receptors that we discussed in class could be studied using patch clamp electrophysiology?

Estrogen receptor

Phospholipase C

Nicotinic acetylcholine receptor

Insulin receptor tyrosine kinase

GPCR

A

Nicotinic acetylcholine receptor

52
Q

Which of the following is NOT a major component of biological membranes?

Carbohydrates

All other choices are all major components of biological membranes

Polar Lipids

Cholesterol

Integral proteins

A

All other choices are all major components of biological membranes

53
Q

Lateral diffusion rates on cell surfaces can be measured by:

glucose transport measurements

FRAP experiments

single particle tracking of fluorescent lipids

patch clamp experiments

FRAP and single particle tracking of fluorescent lipids

A

FRAP and single particle tracking of fluorescent lipids

54
Q

Which of the following molecules is the least oxidized:

Fatty acid

Carboxylic acid

Glycogen

Glucose

Carbon dioxide

A

Fatty acid

55
Q

The fluidity of a lipid bilayer will be increased by which of the following?

Increasing the temperature

Substituting Stearic acid (18:0) for Linoleic acid (18:2)

Decreasing the number of unsaturated fatty acids

Decreasing the temperature

Adding alkyl side chains that are longer

A

Increasing the temperature

56
Q

Which of the following transport mechanisms permits solute transport down a concentration gradient AND requires a conformational change to translocate each substrate across the membrane?

Simple diffusion

Ion channel

Secondary active transport

Facilitated diffusion

Primary active transportv

A

Facilitated diffusion

57
Q

What is the purpose of the Hydropathy Index (or Plot)?

Predicts the charge required to open and close voltage-gate channels.

Predicts segments of globular proteins that would fold to the inside to avoid interactions with water.

Predicts if channels are Symports or Antiports based on delta E.

Predicts the number of solute molecules that pass through a membrane channel per unit of time.

Predicts that a segment of a protein may be transmembrane.

A

Predicts the number of solute molecules that pass through a membrane channel per unit of time.

58
Q

Which of the following cellular processes typically does NOT involve membrane fusion?

Fertilization of an egg by sperm

Endocytosis

You getting infected with a Fall flu virus

Glucose transport into blood from the intestinal lumen

Exocytosis (i.e. secretion)

A

Glucose transport into blood from the intestinal lumen

59
Q

Match the following cell signaling example with the feature it best exemplifies:

Hydrolysis of GTP by Gqa

Specificity

Modularity

Localization

Termination

Amplification

A

Termination

60
Q

A researcher is investigating a potential inhibitor of the GLUT1 glucose transporter protein.

They determine that the Vmax for transport is the same with and without the inhibitor present, but the KT for transport is 5 mM glucose without the inhibitor, and 50 mM glucose with the inhibitor.

Which statement is most likely true about this inhibitor?

None of these other statements is plausible

The inhibitor binds GLUT1 in a different location from glucose

The inhibitor binds GLUT1 only in the presence of glucose

The inhibitor binds covalently to GLUT1

The inhibitor binds GLUT 1 in the same location as glucose

A

The inhibitor binds GLUT 1 in the same location as glucose

61
Q

Which of the following membrane processes is responsible for steroid hormone signal transduction across the plasma membrane?

Primary active transport

Receptor enzymes

Gated ion channel

Simple diffusion

Carrier molecules

A

Simple diffusion

62
Q

____________ membrane proteins ___________________ and can be removed from the membrane without disrupting the membrane, while ______________ membrane proteins require detergents and/or organic solvents to remove from the membrane.

Peripheral
may have functional units on both sides of the membrane
integral

Integral
penetrate deeply into the lipid bilayer
peripheral

Integral,
are usually denatured when released from membranes,
peripheral

Amphitropic,
are generally noncovalently bound to membrane lipids,
peripheral

Peripheral,
are generally noncovalently bound to membrane lipids,
integral

A

Peripheral,
are generally noncovalently bound to membrane lipids,
integral

63
Q

Which statement about sterols is FALSE?

Cholesterol is the principal membrane sterol.

Sterols are soluble in water, but less so in organic solvents such as chloroform.

The sterol backbone is the basis for a number of hormones

Sterols are found in the plasma membranes of eukaryotic cells.

All sterols share a fused-ring structure with four rings.

A

Sterols are soluble in water, but less so in organic solvents such as chloroform.

64
Q

You have raised two groups of tadpoles: one group at 15° C, and the second group at 30° C. You then compare the lipid composition of the plasma membranes for the two groups of tadpoles. Which of the following statements best describes the membranes of these tadpoles:

The group raised at 15° C has more unsaturated fatty acids, and the group raised at 30° C has more saturated fatty acids.

The two groups of tadpoles have identical lipid compositions, but the membranes of the group raised at 30° C are less fluid.

The group raised at 30° C has more unsaturated fatty acids, and the group raised at 15° C has more saturated fatty acids.

The two groups of tadpoles have identical lipid compositions, but the membranes of the group raised at 15° C are less fluid.

A

The group raised at 15° C has more unsaturated fatty acids, and the group raised at 30° C has more saturated fatty acids.

65
Q

What group of lipids serves as the basis for the ABO blood group system?

Ether Lipids

Sphingomyelins

Glycerophospholipids

Triglycerides

Glycosphingolipids

A

Glycosphingolipids

66
Q

Which statement is FALSE regarding the Oleic acid hydrocarbon [18:1(Δ9)]?

It has a much lower melting point than steric acid (18:0)

All of the above are true statements

It can pack tighter together than steric acid due to the higher relative flexibility of its structure

It can be classified as an unsaturated lipid molecule

There is a single double bond between carbons 9 and 10

A

It can pack tighter together than steric acid due to the higher relative flexibility of its structure

67
Q

Triacylglycerols

Can sometimes be substituted with a carbohydrate group

Are usually planar molecules, which permits their tight packing in cells

Provide a means in which to store energy and act as insulators

Are composed of a glycerol backbone and 2 fatty acids plus a third group (usually an alcohol)

Are the main component of membrane lipids

A

Provide a means in which to store energy and act as insulators

68
Q

Match the following cell signaling example with the feature it best exemplifies:

Use of SH2 domains to bind phosphotyrosine residues

Amplification

Integration

Modularity

Termination

Specificity

A

Modularity

69
Q

Signal amplification is an important feature of many, but not all, signaling events. Which of the following signaling events do not include amplification?

A nuclear hormone receptor that turns gene expression off
Ligand binding triggers opening of a calcium channel
The insulin receptor signaling cascade

I and II only

I and III only

I only

All three signaling pathways include an amplification event

I, II, and III

A

I only

70
Q

Phospholipases

Can produce fatty acids by hydrolysis of an ester bond in a phospholipid

Are named according to the specific bond they hydrolyze and not by their substrates

Can cleave fatty acids from gangliosides by hydrolysis of diester linkages

A and B are both true statements

A and C are both true statements

A

A and B are both true statements

71
Q

Consider the membrane potential of a typical metabolizing cell. Which of the best mechanisms is the best strategy for the cell to export ammonium (NH4+)? (Assume the concentration of ammonium is equal inside and outside the cell).

Simple diffusion

H+/ammonium symport

H+/ammonium antiport

Uniport

Ion channel

A

H+/ammonium antiport

72
Q

Phospholipase C can use phosphatidylinositol 4,5-bisphosphate (PIP2) as a substrate to produce which of the following molecules that directly causes the release of intracellular calcium?

I. Adenosine 3’,5’-cyclic monophosphate (cAMP)

II. Diacylglycerol (DAG)

III. Inositol 1,4,5-trisphosphate (IP3)

IV. Protein Kinase C (PKC)

I only

IV only

II and III

II only

III only

A

III only

73
Q

Which of the following is NOT an example of signal termination?

GAPs strongly stimulate GTPase activity causing hydrolysis of the GTP bound to the trimeric G-protein

Estrogen production decreases below Kd of its receptor

The gate of the nicotinic acetylcholine receptor closes while nicotine remains bound

A cell takes up signaling peptides by endocytosis and sends them to the lysosome for degradation

Acetylcholine esterase hydrolyzes all of the acetylcholine in the gap junction

A

The gate of the nicotinic acetylcholine receptor closes while nicotine remains bound

74
Q

An incorrect feature of G-proteins (Guanine Nucleotide Binding Proteins) is that:

They include heterotrimeric proteins as a major subclass

They are kinases.

They inactivate themselves by hydrolyzing GTP.

They include low molecular weight proteins as a major subclass

They are active in their GTP bound state.

A

They are kinases.

75
Q

Which of the following are structurally most closely related to cholesterol?

Tocopherols, like Vitamin E

Steroid hormones

Eisosanoids

Phosphatidylinositols

Retinoids, like Vitamin A derivatives

A

Steroid hormones

76
Q

What specific class of enzymes hydrolyze the ester bonds of glycerophospholipids?

Protein Kinases

Sialidases

Phosphorylases

Phospholipases

Phosphatases

A

Phospholipases

77
Q

What is the abbreviated nomenclature for a polyunsaturated 22-carbon omega-3,6 fatty acid that contains no other double bonds?

22:2(Δ 16,19)

22:1(Δ 19)

22:2(Δ 13,19)

22:1( Δ 16)

22:2(Δ 13,16)

A

22:2(Δ 16,19)

78
Q

Which of the following does NOT describe signal termination?

beta-arrestin binds to a GPCR and prevents a trimeric G-protein from accessing its binding site on the GPCR

The pancreas stops secreting the insulin, and the level of this hormone in the blood stream drops below the binding constant of the receptor

Acetylcholine esterase hydrolyzes acetylcholine in the synaptic cleft

Phospholipase C is inactivated and enzymes convert the remaining diacylglycerol to phosphatidic acid

GAPs stimulate the trimeric G-protein’s GTPase activity, causing GTP hydrolysis

A

beta-arrestin binds to a GPCR and prevents a trimeric G-protein from accessing its binding site on the GPCR

79
Q

Which of the following are phospholipids that contain an ether-linked alkyl group?

Cerebrosides

Glycosphingolipids

Globosides

Plasmalogens

Sphingomyelins

A

Plasmalogens

80
Q

Which of the following statements is FALSE regarding the insulin receptor?

Insulin binding causes autophosphorylation on Tyr residues

Activated receptors can induce transcription

Several steps of the signaling cascade involve phosphorylation, and amplification of the first signal at each step, so there is no requirement for either class of G-protein

The receptor changes conformation upon binding of its ligand (insulin).

It is a member of the Receptor Enzyme class

A

Several steps of the signaling cascade involve phosphorylation, and amplification of the first signal at each step, so there is no requirement for either class of G-protein

81
Q

An example of signal termination is when:

Your eyes adjust to a brightened room

B-arrestin binds a receptor, leading it to be endocytosed

The concentration of the signaling molecule drops below the Kd of the receptor

All of these

The signal is amplified until there are no more enzymes in the cascade to phosphorylate

A

The concentration of the signaling molecule drops below the Kd of the receptor

82
Q

Which of the following is important in developing an electrochemical gradient?

Membrane Potential (Vm)

Concentration gradient

Ka, the Acid-Base Constant

A and B only

A, B and C are all important in developing an electrochemical gradient

A

A and B only

83
Q

What is the accepted minimum number of amino acids required for a portion of a protein to span the lipid bilayer of a membrane?

20

50

100

5

Varies with the size of the R-group, so there is no accepted minimum

A

20

84
Q

A process not involving the fusion of two membranes or two regions of the same membrane is:

fertilization of an oocyte by a sperm cell.

propagation of the membrane voltage potential in neurons

creation of pores between adjacent cells

entry of enveloped viruses into cells.

release of neurotransmitters at a synapse.

A

propagation of the membrane voltage potential in neurons

85
Q

What specific group of lipids have the following properties: long-chain (C14-C36) fatty acids bonded to long-chain (C16-C30) alcohols, chains are usually saturated and unsaturated?

Cerebrosides

Glycosphingolipids

Triacylglycerols

Globosides

Waxes

A

Waxes

86
Q

steroid hormone receptors are different than the other signal transduction mechanisms we talked about because:

Their response time is hours-to-days

The signal molecules pass through the plasma membrane

All of these

They don’t make use of second messengers

A

All of these

87
Q

We can calculate the energy required to move a charged solute, like bicarbonate, across a membrane using the transport formula, it relates the Transport Constant (GT) to some electrical measurements and the ratio of solute concentrations on either side of the membrane. Which of the following other constants and abbreviations is NOT in that formula?

Faraday’s Constant

Δψ, in volts

Gas Constant

Z, the charge of the ion

n, the number of ions moved

A

n, the number of ions moved

88
Q

Which of the following statements about receptor enzymes is FALSE?

Receptor enzyme signaling cascades may include G proteins

Some receptor enzymes have tyrosine kinase activity

Receptor enzymes may directly catalyze the synthesis of second messengers

Receptor enzymes are typically polytopic membrane proteins

Integral membrane adenylyl kinases are examples of receptor enzymes

A

Integral membrane adenylyl kinases are examples of receptor enzymes

89
Q

Which of the following can induce membrane curvature?

The ratio of saturated versus unsaturated fatty acids
Peripheral membrane proteins such as BAR domains
Monotopic membrane proteins such as caveolin

II only

II and III only

I, II, and III

III only

I only

A

II and III only

90
Q

Which of the following amino acids are likely to contribute to the ligand binding site of a glycerol transporter:

Ser, Asn

Trp, Tyr

Gly, Ala

Asp, Arg

Ile, Val

A

Ser, Asn

91
Q

Which of the following could describe the composition of globoside:

1 sphingosine, 2 fatty acids, 1 glucose

1 Sphingosine, 1 fatty acid, 1 glucose

1 sphingosine, 1 fatty acid, 2 glucose

1 sphingosine, 2 fatty acids, 2 glucose

A

1 sphingosine, 1 fatty acid, 2 glucose

92
Q

Many diverse signaling pathways use cAMP as a second messenger. This is an example of the following principle:

Modularity

Localization

Integration

Desensitization

Termination

A

Modularity

93
Q

Which of the following statements is FALSE concerning biological membranes?

Aquaporin is a good example of a protein involved in Passive Transport

The Chloride-bicarbonate exchanger is best classified as a Symport

The inner and outer leaflets of the plasma membrane have different lipids

One difference between Primary and Secondary Active Transport is the number of different molecules transported

The lipid composition of the plasma membrane is usually significantly different than any intracellular membrane

A

The Chloride-bicarbonate exchanger is best classified as a Symport

94
Q

Independently, both insulin and epinephrine signaling lead to an increase in blood glucose levels. However, if both signaling cascades are activated at the same time, insulin signaling decreases epinephrin signaling to prevent blood glucose levels from becoming too high. This is an example of:

Modularity

Specificity

Amplification

Termination

Integration

A

Integration

95
Q

Which of the following is NOT a feature that directly contributes to the Transition Temperature of lipids in membranes?

The relative concentration of saturated fatty acids

The relative concentration of sterols

The relative polarity of fatty acids

Only A and B above relate to the Transition Temperature of membrane lipids

A, B, and C above all relate directly to the Transition Temperature of membrane lipids

A

Only A and B above relate to the Transition Temperature of membrane lipids

96
Q

Which statement about membranes is FALSE?

Lipids can freely pass from one leaflet to another in membranes

The inner and outer leaflets of membranes differ in lipid and protein compositions.

The lipid:protein ratio varies between tissues and organisms.

Transport of many solutes requires the action of integral membrane proteins.

Individual lipids can move freely in a lateral direction in membranes.

A

Lipids can freely pass from one leaflet to another in membranes

97
Q

A cerebroside includes

A globoside with 3 or more esterified sugars

A phosphate group on carbon 3

A monosaccharide on ceramide

Sphingosine plus a long alcohol

A repeated disaccharide linked by a short peptide

A

A monosaccharide on ceramide

98
Q

Match the following cell signaling example with the feature it best exemplifies:

Cyclization of ATP to cAMP

Amplification

Localization

Specificity

Termination

Modularity

A

Amplification

99
Q

Adenylyl cyclase catalyzes the formation of cAMP in direct response to

An extracellular messenger

Hydrolysis of GTP by a bound G-protein

Binding of a GDP-bound G-protein

Binding of a GPCR

Binding of a GTP-bound G-protein

A

Binding of a GTP-bound G-protein

100
Q

Which of the following sphingolipids is not also a glycolipids

Ganglioside
Globoside
Cerebroside
Sphingomyelin

A

Sphingomyelin

101
Q

Which statement concerning membranes architecture is FALSE?

The inner and outer plasma membrane bilayers have an asymmetric distribution of phospholipids

Peripheral membrane proteins can be removed without damaging membrane integrity and without removing integral membrane proteins

Membranes are impermeable to simple diffusion of charged solutes

Carbohydrates are located only on the outer face of the plasma membrane

All internal membranes of Eukaryotic cells have the same relative proportions of the various phospholipids

A

All internal membranes of Eukaryotic cells have the same relative proportions of the various phospholipids

102
Q
A

MCDB 310 (3 decks)

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