Brainscape's Knowledge GenomeTM

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


See full index

BIOCHEM > Second 50 > Flashcards

Second 50 Flashcards

1
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
2
Q

Less condensed, gene-rich chromatin is referred to as

nucleosomes.

histones.

heterochromatin.

euchromatin.

A

euchromatin.

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

Two identical copies of replicated DNA that remain attached until cell division are referred to as

telomeres.

centromeres.

kinetochores.

sister chromatids.

A

sister chromatids.

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

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

exons.

operons.

introns.

promoters.

A

operons.

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

The mixing and matching of novel genes in eukaryotic cells occurs through

operons.

exon shuffling.

promoter regions.

untranslated regions.

A

exon shuffling.

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

Deletions or insertions into the genome cause a polymorphism called

short tandem repeats.

variable number tandem repeats.

long tandem repeats.

single nucleotide polymorphism.

A

short tandem repeats.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
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
9
Q

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

gel electrophoresis

blue-white screening

antibiotic resistance

fluorescent labeling

A

gel electrophoresis

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

In the second temperature phase of PCR, why does the temperature vary from 55mc060-1.jpgC to 65mc060-2.jpgC?

different ionic strengths

different primer concentrations

G-C content

different amount of hydrogen bonds

A

G-C content

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

Identify the phase of PCR amplification where DNA is denatured and the strands are separated.

A

B

C

D

A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
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
13
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
14
Q

The chirality of naturally occurring amino acids in proteins is

R.

L.

D.

the same as glyceraldehyde.

A

L.

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

Using the pKas shown, what is the isoelectric point of the amino acid tyrosine?

<1.0

  1. 5
  2. 0
  3. 75
A

5.5

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

What are the three-letter and one-letter abbreviations for the amino acid tyrosine?

Tyo, T

Tyr, R

Tro, Y

Tyr, Y

A

Tyr, Y

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

Which linear sequence of bonded atoms can be found in the backbone of polypeptides?

C-N-N-C

C-C-N-C

N-C-C-C

C-O-C-N

A

C-C-N-C

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

The peptide bond

is most stable in the cis configuration.

has a mix of single and double bond characters.

can rotate around the carbonyl and N bond but not around the mc068-1.jpg-carbon and N bond.

can function as a weak acid and weak base.

A

has a mix of single and double bond characters.

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

The peptide bond is stronger than the ester bond. What structural feature of the peptide bond gives it additional bond strength?

Resonance structures give the peptide bond some double bond character.

The peptide bond is between carbon and nitrogen instead of carbon and oxygen atoms.

The peptide bond is more polar.

Peptide bonds can hydrogen bond.

A

Resonance structures give the peptide bond some double bond character.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
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
21
Q

Using the table below, determine the kind of gene mutation illustrated.
ATG_AAT_CAC –> ATG_AAG_CAC

missense mutation

nonsense mutation

frameshift mutation

silent mutation

A

missense mutation

22
Q

All of the following are types of protein secondary structure EXCEPT

B sheets

a-helixes

B-helixes

B-turns

A

B-helixes

23
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 are left handed, whereas B-sheets are right handed in arrangement.

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.

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.

24
Q

What is the minimum number of amino acids needed to make one turn of an mc074-1.jpg-helix?

3

4

6

7

A

4

25
Q

Which of the following statements about B-sheet structures is true?

The individual strands of all B-sheet structures are connected by turns, helices, or loops.

All amino acid side chains in antiparallel and parallel B-sheet structures point to one side of the sheet.

Parallel B-sheet structures have backbone amides that directly hydrogen bond between strands, whereas antiparallel B-sheets have hydrogen bonds that are offset.

All B-sheet structures form a spiraling backbone chain.

A

The individual strands of all B-sheet structures are connected by turns, helices, or loops.

26
Q

What is a difference between parallel and antiparallel B-sheet secondary structures?

Antiparallel B-sheets have a larger number of stabilizing H bonds between backbone amides than parallel B-sheets.

Parallel B-sheets require a larger loop connecting together the individual peptide strands in the sheet.

Parallel B-sheets are longer than antiparallel sheets.

Parallel B-sheets have amino acid side chains alternating up and down, whereas antiparallel side chains alternate down and up.

A

Parallel B-sheets require a larger loop connecting together the individual peptide strands in the sheet.

27
Q

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

0

3

4

5

A

3

28
Q

Which class of protein structures does the protein shown below fit into?

predominantly a-helical

predominantly B-sheet

intermixed a-helix and B-sheet

domains of a-helix adjacent to domains of B-sheet

A

predominantly B-sheet

29
Q

The common protein fold shown below is the __________ fold.

Greek key

Rossman

FERM domain

a/B barrel

A

a/B barrel

30
Q

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

a-helices.

nucleotides.

cytochromes.

membranes.

A

nucleotides.

31
Q

Protein tertiary structures

require the formation of disulfide bonds in order to achieve their native state.

are always irreversibly destroyed by the addition of denaturants, such as urea and salts, even when the denaturants are subsequently removed.

are often disrupted by the either very low pH or very high pH values as a result of alterations in the ionization states of acidic or basic amino acids.

are generally poorly defined and cannot be determined experimentally.

A

are often disrupted by the either very low pH or very high pH values as a result of alterations in the ionization states of acidic or basic amino acids.

32
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.

33
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.

34
Q

Which gives rise to a favorable enthalpic (mc084-1.jpgS) 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.

35
Q

Of the three proposed models of globular protein folding, which one describes the initial formation of all secondary structures, followed by the arrangement of those secondary structures into a final tertiary structure?

mutant globule

hydrophobic collapse model

framework model

nucleation model

A

framework model

36
Q

Why is the process of purifying proteins from cells considered challenging?

Proteins are insoluble.

The process is expensive and time consuming.

There is no way to determine the structure of the protein.

There are 10,000 to 100,000 proteins in one sample.

A

There are 10,000 to 100,000 proteins in one sample.

37
Q

When preparing to isolate proteins from plant cells, the first step in preparing the cell homogenate would be

sonication.

using a French press.

treatment with mild detergents.

enzymatic treatment.

A

enzymatic treatment.

38
Q

After centrifugation, the purity of the protein is determined by

absorbance measurements.

activity units.

total protein content.

specific activity.

A

specific activity.

39
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

40
Q

Calculate the specific activity when 500 mg of protein has an activity of 18,000 units.

0.28 units/mg protein

36 units/mg protein

9000 units/mg protein

13,000 units/mg protein

A

9000 units/mg protein

41
Q

The advantage of using a native PAGE gel compared with an SDS-PAGE gel is that the native PAGE gel

separates proteins only based on molar mass.

gives information on the charge or conformation of the protein.

results in a better separation of small proteins.

increases the resolution of large and small proteins.

A

gives information on the charge or conformation of the protein.

42
Q

Two-dimensional polyacrylamide gel electrophoresis separates proteins based on

pI and shape.

ligand affinity and molecular weight.

shape and ligand affinity.

pI and molecular weight.

A

pI and molecular weight.

43
Q

In isoelectric focusing, a protein with a pH below the pI would

migrate toward the anode.

migrate toward the cathode.

stop migrating.

migrate, but there is no way to determine the direction.

A

migrate toward the cathode.

44
Q

Which enzyme or reagent cleaves a peptide at the carboxyl side of a methionine residue?

trypsin

chymotrypsin

V-8 protease

cyanogen bromide

A

cyanogen bromide

45
Q

A polypeptide was digested by trypsin and chymotrypsin. Use the following information to determine the polypeptide sequence.

Trypsin Digest Chymotrypsin Digest
LMYK CE
MGFCE LMYKW
WDER DERMGF

ECFGMREDWKYLM

LMYKWMGFCEDER

LMYKWDERMGFCE

CELMYKWDERMGF

A

LMYKWDERMGFCE

46
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.

47
Q

Which technique ionizes polypeptides by releasing them from a small metallic capillary at high voltage?

ESI

MALDI

NMR

X-ray crystallography

A

ESI

48
Q

Which technique ionizes polypeptides by embedding the tryptic fragments into a light-absorbing matrix and exposing it to a laser?

ESI

MALDI

NMR

X-ray crystallography

A

MALDI

49
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.

50
Q

In solid-phase peptide synthesis, which reagent is used to remove the peptide from the solid resin support?

HF

DCC

Fmoc

PITC

A

HF

BIOCHEM (7 decks)

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