Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOCHEM > more prac > Flashcards

more prac Flashcards

1
Q

In DNA the phosphate groups are on the outside of the helix. Why does this stabilize the structure?

hydrogen bonding with itself

ionic interactions with the solvent

covalent binding to the solvent

It does not stabilize the structure.

A

ionic interactions with the solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the cause of the overall negative charge of a molecule of DNA?

hydrogen bonding between base pairs

the sugars

the phosphate backbone

the antiparallel orientation of the DNA

A

the phosphate backbone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cell signaling and cell membranes are examples of functions performed by which biomolecule?

amino acid

nucleotide

simple sugar

fatty acid

A

fatty acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

If the equilibrium constant (Keq) is greater than 1, which direction will the reaction proceed?

spontaneously to reactants

neither direction

spontaneously to products

Not enough information is given to determine the direction of reaction.

A

spontaneously to products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Under what conditions could a biological reaction spontaneously proceed to reactants if the mc028-1.jpg?

Reactant concentrations are greater than product concentrations.

Product concentrations are greater than reactant concentrations.

Reactant concentrations are equal to product concentrations.

There are no conditions where this could happen.

A

Product concentrations are greater than reactant concentrations.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The interaction between an amino group and a carboxylate group is best characterized as

hydrogen bonds.

ionic interactions.

van der Waals interactions.

a covalent bond.

A

ionic interactions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The K+ ion concentration in a DNA sample is increased from 50 mM to 100 mM. The Tm will

increase.

remain the same.

decrease.

vary unpredictably.

A

increase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

During eukaryotic DNA condensation, nucleosomes are packed together to form

histones.

chromatin.

chromosomes.

genes.

A

chromatin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Polycistronic genes that contain a coding sequence for proteins that are only involved in one biochemical process are called

exons.

introns.

promoters.

operons.

A

operons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In the eukaryotic cell, the coding sequences on a gene are referred to as

exons.

operons.

introns.

promoter.

A

exons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When a gene sequence is cloned using mRNA, which enzyme is used to seal the single-strand gaps left behind in the second strand of DNA?

DNA methylase

restriction endonucleases

reverse transcriptase

DNA ligase

A

DNA ligase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When DNA is sequenced, which analytical technique is used to separate the chain-terminated DNA fragments?

blue-white screening

gel electrophoresis

antibiotic resistance

fluorescent labeling

A

gel electrophoresis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

This method of analyzing RNA transcripts relies on a predetermined collection of complementary DNA sequences.

plasmid cloning

viral transduction

RNA-seq

gene-expression microarrays

A

gene-expression microarrays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which method of analyzing RNA transcripts is considered to be an unbiased approach because it does not use a predetermined collection of complementary DNA sequence?

plasmid cloning

viral transduction

RNA-seq

gene-expression microarrays

A

RNA-seq

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Use the table below to determine how many possible RNA sequences could code for the dipeptide Pro-Ala.

1

16

8

64

A

16

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

All of the following are types of protein secondary structure EXCEPT

B-sheets.

a-helixes.

B-helixes.

B-turns.

A

B-helixes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which statement regarding protein secondary structures is correct?

B-strands allow a-helices to interact with one another.

Protein a-helices alternate with B-strands in stabilizing protein structure.

Protein a-helices and B-strands differ in that a-helices are stabilized by intrahelical hydrogen bonds, whereas B-strands are stabilized by hydrogen bonds across adjacent strands.

Protein a-helices are left handed, whereas B-sheets are right handed in arrangement.

A

Protein a-helices and B-strands differ in that a-helices are stabilized by intrahelical hydrogen bonds, whereas B-strands are stabilized by hydrogen bonds across adjacent strands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the minimum number of amino acids needed to make one turn of an a-helix?

3

4

6

7

A

4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How many B-turns or B-loops are required to construct a B-sheet composed of four antiparallel strands?

0

3

4

5

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The protein fold known as the Rossman fold is found in proteins that commonly bind

a-helices.

nucleotides.

cytochromes.

membranes.

A

nucleotides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

At the interface between subunits of a protein with quaternary structure, which of the following interactions between amino acid side chains would contribute to the stability of the dimer?

glutamate–aspartate.

leucine–aspartate.

glutamate–lysine.

phenylalaninelysine.

A

glutamate–lysine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In multi-subunit proteins, such as hemoglobin, the different subunits are usually bound to one another by all of the following EXCEPT

hydrogen bonds.

electrostatic interactions.

hydrophobic interactions.

peptide bonds.

A

peptide bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which gives rise to a favorable enthalpic (delta S) driving force for protein folding?

The lining up of hydrogen bonds as the protein folds.

The limiting of possible conformations as the protein folds.

The decrease in ordered water molecules as hydrophobic amino acids pack together.

The stabilization caused by favorable electrostatic interactions of amino acid side chains.

A

The decrease in ordered water molecules as hydrophobic amino acids pack together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

After centrifugation, there is a 10% decrease in activity and a 75% decrease in total protein. What is purification of the target protein?

  1. 28-fold
  2. 3-fold
  3. 6-fold
  4. 5-fold
A

3.6-fold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In tandem mass spectrometry, the first mass spectrometer

determines the nuclear spin of the atoms.

determines the mass of peptide subfragments.

uses bioinformatics to compare the masses of the peptides.

uses electrospray ionization to select peptide fragments.

A

uses electrospray ionization to select peptide fragments.

FIRST = spray

26
Q

In tandem mass spectrometry, the second mass spectrometer

determines the nuclear spin of the atoms.

determines the mass of peptide subfragments.

uses bioinformatics to compare the masses of the peptides.

uses electrospray ionization to select peptide fragments.

A

determines the mass of peptide subfragments.

SECOND = “sub”(fragments)

27
Q

During the production of polyclonal antibodies, how are the antigen-specific antibodies purified?

dialysis

gel electrophoresis

size exclusion chromatography

affinity chromatography

A

affinity chromatography

28
Q

In monoclonal antibody generation, the cells that produce the antibody in the animal are located in __________ cells.

heart

spleen

liver

red blood

A

spleen

29
Q

The part of the Western blot that contains the protein-specific recognition and facilitates the antigen-antibody interactions is the

SDS-PAGE gel.

primary antibody.

tertiary antibody.

filter membrane.

A

primary antibody.

30
Q

An enzyme that requires the coenzyme nicotinamide adenine dinucleotide belongs to which enzyme class?

transferases

isomerases

ligases

oxidoreductases

A

oxidoreductases

31
Q

All of the following are common catalytic reaction mechanisms in enzyme active sites EXCEPT __________ catalysis.

acid–base

covalent

metal ion

van der Waals

A

van der Waals

32
Q

When a nucleophile present in the enzyme attacks an electrophilic substrate to form an enzyme-substrate intermediate, this is an example of __________ catalysis.

covalent

acid–base

metal ion

hydrophobic

A

covalent

33
Q

The regulation of a biomolecule through the addition or removal of a molecular tag involves __________ reactions.

coenzyme-dependent redox

metabolite transformation

isomerization

reversible covalent modification

A

reversible covalent modification

34
Q

Which type of reaction does not change the molecular formula of the product compared with that of the substrate?

isomerization

condensation

reduction

hydrolysis

A

isomerization

iso = does not change

35
Q

Which type of interaction is more likely to be found between an enzyme and an irreversible inhibitor?

covalent bond

hydrogen bond

ionic interaction

van der Waals interaction

A

covalent bond

36
Q

A mixture of enzyme and inhibitor is run through a size-exclusion chromatography column. The activity of the enzyme is assessed before and after the chromatography. The enzyme has more activity after the chromatography step. Which of the following is true?

The enzyme was not eluted fully from the column.

The enzyme was denatured during chromatography.

The inhibitor is a reversible inhibitor.

The inhibitor is an irreversible inhibitor.

A

The inhibitor is a reversible inhibitor.

37
Q

An inhibitor that binds only to the ES complex and not free enzyme is known as a(n) __________ inhibitor.

irreversible

competitive

uncompetitive

mixed

A

uncompetitive

38
Q

A Lineweaver–Burk plot displays parallel lines for an enzyme in the absence and presence of increasing amounts of an inhibitor. The inhibitor in this experiment

binds both the free enzyme and the ES complex.

is competitive.

alters the Km but not the vmax.

is uncompetitive.

A

is uncompetitive.

39
Q

Which protein is part of the TNF receptor–activated programmed cell death signaling pathway?

FADD

TRAF2

NFκB-inducing kinase

IKK

A

FADD

40
Q

Phosphorylation of which of the following is necessary for the increased expression of antiapoptotic genes?

RIP

TNF receptor

FADD

IKK

A

IKK

41
Q

Which of the following is an energy conversion pathway?

urea cycle

citrate cycle

nitrogen fixation and assimilation

fatty acid degradation and synthesis

A

citrate cycle

42
Q

In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (delta G) of 23.8 kJ/mol. Under what conditions (encountered in erythrocytes) will the free-energy change (delta G) be negative, enabling the reaction to proceed to products?

The free-energy change will be negative if the concentrations of the two products are high relative to that of fructose 1,6-bisphosphate.

The reaction will not go to the right spontaneously under any conditions because the delta G is positive.

Under standard conditions, enough energy is released to drive the reaction to the right.

The free-energy change will be negative when there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products.

A

The free-energy change will be negative when there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products.

43
Q

In two turns of the citrate cycle, how many electrons are transferred from the citrate cycle intermediates to NAD+ and FAD?

4

8

12

16

A

16

44
Q

The primary function of the citrate cycle is to oxidize

glucose.

pyruvate.

acetyl-CoA.

citrate.

A

acetyl-CoA.

45
Q

Which of the following is a reactant in the net reaction of the citrate cycle?

CO2

H2O

GTP

CoA

A

H2O

46
Q

Which molecule in the net reaction of the citrate cycle contributes to the inhibition of pyruvate dehydrogenase?

FAD

H2O

H+

NADH

A

NADH

47
Q

Coenzyme A is derived from which of the following vitamins?

thiamine

pantothenic acid

riboflavin

niacin

A

pantothenic acid

48
Q

Which vitamin is the precursor to the coenzyme that functions as a reductant in the pyruvate dehydrogenase complex in the final step of the reaction?

thiamine

pantothenic acid

riboflavin

niacin

A

riboflavin

49
Q

How would a high NADH to NAD+ ratio be expected to affect the pyruvate dehydrogenase reaction?

The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an increase in pyruvate dehydrogenase activity.

The last step of the pyruvate dehydrogenase reaction is blocked, resulting in a decrease in activity.

The E1 subunit is phosphorylated by pyruvate dehydrogenase kinase, and the catalytic activity of pyruvate dehydrogenase decreases.

The pyruvate dehydrogenase phosphatase-1 enzyme would increase, resulting in pyruvate dehydrogenase activation at an accelerated rate.

A

The last step of the pyruvate dehydrogenase reaction is blocked, resulting in a decrease in activity.

50
Q

How would an increased level of acetyl-CoA be expected to affect the pyruvate dehydrogenase reaction?

The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an inhibition of pyruvate dehydrogenase activity.

The last step of the pyruvate dehydrogenase reaction would be blocked, resulting in a decrease in activity.

The E1 subunit would be phosphorylated by pyruvate dehydrogenase kinase, and the catalytic activity of pyruvate dehydrogenase would decrease.

The pyruvate dehydrogenase phosphatase-1 enzyme would increase, resulting in pyruvate dehydrogenase activation at an accelerated rate.

A

The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an inhibition of pyruvate dehydrogenase activity.

51
Q

The reaction catalyzed by __________is the most endergonic reaction in the citrate cycle.

fumarase

succinate dehydrogenase

malate dehydrogenase

aconitase

A

malate dehydrogenase

52
Q

The reaction catalyzed by __________ is likely to be reversible under cellular conditions according to the delta G.

malate dehydrogenase

citrate synthase

succinate dehydrogenase

a-ketoglutarate dehydrogenase

A

succinate dehydrogenase

REVERSIBLE SUCC

53
Q

A high concentration of which molecule would inhibit citrate synthase in the citrate cycle?

AMP

ADP

NAD+

ATP

A

ATP

54
Q

Which anaplerotic reaction balances the input of oxaloacetate with acetyl-CoA in the citrate cycle by converting pyruvate into oxaloacetate?

pyruvate carboxylase

malate dehydrogenase

malic enzyme

pyruvate kinase

A

pyruvate carboxylase

55
Q

The anaplerotic reaction catalyzed by pyruvate carboxylase requires which coenzyme?

niacin

biotin

riboflavin

thiamine

A

biotin

56
Q

Which citrate cycle intermediate is siphoned off the citrate cycle during starvation?

succinyl-CoA

malate

a-ketoglutarate

fumarate

A

malate

57
Q

Which citrate cycle metabolite is used as a precursor for heme biosynthesis?

succinyl Co-A

oxaloacetate

a-ketoglutarate

malate

A

succinyl Co-A

heme bio succ

58
Q

Predict the fate of a-ketoglutarate when it is not used in the citrate cycle.

cholesterol synthesis

heme synthesis

gluconeogenesis

amino acid synthesis

A

amino acid synthesis

59
Q

What is the location of the electron transport system protein called cytochrome c?

cytoplasm

mitochondrial matrix

inner mitochondrial membrane

intermembrane space

A

intermembrane space

cyto to space

60
Q

What would happen to a mutated ATP synthase enzyme where the proton binding aspartate residue on the c subunits was mutated to an alanine?

The enzyme would make ATP as normal in the presence of a proton gradient.

The enzyme would not make ATP in the presence of a proton gradient.

The enzyme would make ATP without the need for a proton gradient.

The rotor would rotate in response to a proton gradient, but no ATP would be made.

A

The enzyme would not make ATP in the presence of a proton gradient.

61
Q

What is the cellular location of eukaryotic thermogenin (or uncoupling protein)?

mitochondrial inner membrane

mitochondrial matrix

cytoplasm

both cytoplasm and mitochondrial matrix

A

mitochondrial inner membrane

BIOCHEM (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions