Brainscape's Knowledge GenomeTM

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


See full index

Genetics Tuskegee > Biochem Exam 2 > Flashcards

Biochem Exam 2 Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

A peptide built from three amino acids must have

A

three side chains

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

What happens soonest during the protein folding process?

A

Hydrophobic groups move to the protein interior

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

At a pH above its pKa, the e-amino group of lysine is

A

deprotonated and neutral

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

What is the N-terminal residue of the peptide AYSDG?

A

Alanine

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

In an alpha helix, each carbonyl group

A

is a hydrogen bond acceptor

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

Which of the following amino acids is generally absent from an alpha-helix?

A

Proline

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

Which of the following is most critical for maintaining the tertiary structure of a protein?

A

hydrophobic interactions

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

Three of the 20 amino acids that are incorporated into proteins are aromatic. They are:

A

tyrosine, phenylalanine, and tryptophan

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

The predominant non-covalent interaction seen in alpha-helices and beta-sheets is

A

hydrogen bonds

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

Which statement is FALSE about the classification of amino acids?

A

Glutamic acid and asparagine are negatively charged amino acids

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

Which of the following best describes the side chains of the nonpolar amino acids (glycine is not included)?

A

They are primarily neutral hydrocarbon structures

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

If an alpha-helical region of a protein contained 18 amino acid residues, how many helical turns would be present?

A

5

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

Which of the following forces stabilize protein primary structure at physiological pH?

A

covalent bonds

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

Which of the following statements about peptide bonds in FALSE. Peptide bonds are:

A

charged

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

Amino acid residues with nonpolar side chains are mostly located in the protein interior because

A

nonpolar groups cannot interact with water molecules

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

Which of the following statements about the peptide bond is FALSE?

A

It is a phosphodiester bond

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

Which of the following is FALSE with respect to beta-sheets?

A

Amino acid side chains protrude from one side of the beta-sheet

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

Which of the following statements about the alpha-helix and beta-sheet are TRUE?
1. They are both types of secondary structure.
2. They are both stabilized by hydrogen bonds between amino acid side chains.
3. The polypeptide backbone is fully extended in both structures.
4. They are both usually located in the interior of soluble globular proteins

A

1 and 4

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

A domain is:

A

a folded segment of polypeptide with a separate hydrophobic core

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

What is the primary driving force in the formation of protein tertiary structure?

A

The exclusion of non-polar substances from aqueous solution

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

What ultimately determines the unique three-dimensional structure of soluble globular proteins?

A

The sequence of the amino acid residues

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

A polypeptide that does not assume its proper three-dimensional structure

A

may be degraded, may re-fold, may accumulate

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

To dislodge a protein bound to a carboxymethyl column, you should add a solution containing

A

a higher concentration of cations

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

Hemoglobin’s oxygen-binding curve is sigmoidal because

A

O2 binding shifts hemoglobin to a high-affinity conformation

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

Respiring tissues release CO2, which leads to

A

a shift to the T state of hemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Calculate the fractional saturation for myoglobin when pO2 is a. 20 torr and b. 80 torr.

A

The fractional saturation at 20 and 80 torrs are 0.88 and 0.97, respectively, which indicate the myoglobin is 88% and 97% saturated with oxygen at these respective pressures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

A protein that consists of more than one polypeptide chain has

A

quaternary structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Which of the following statements is FALSE? In its interaction with hemoglobin, oxygen is:

A

a prosthetic group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Structurally, myoglobin and hemoglobin are very similar proteins. In which of the following levels of structure do they differ most?

A

Quaternary structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Which cytoskeletal proteins are constructed from globular protein subunits?

A

actin filaments and microtubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

The changes in cell shape that allow crawling are mainly the result of

A

actin filament assembly and disassembly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Which type of structural protein is exclusively extracellular?

A

collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Phalloidin, a peptide isolated from a poisonous mushroom, binds to F-actin but not G-actin. How does the addition of phalloidin affect cell motility?

A

cell mobility is impared

34
Q

The motor protein myosin has

A

two heads attached to a rigid neck lever

35
Q

Straight hair can be curled and curly hair can be straightened by exposing wet hair to a reducing agent, repositioning the hair with rollers, then exposing the hair to an oxidizing agent. What are the roles of the reducing and oxidizing agents?

A

The reducing agent breaks disulfide bonds; the oxidizing agent forms new disulfide bonds

36
Q

“Hard” keratins such as those found in hair, horn, and nails have a high sulfur content whereas “soft” keratins found in the skin have a lower sulfur content. Explain the structural basis for this observation.

A

Hard keratins have oxidized cysteine residues, which enhance stability through disulfide bonds

37
Q

Kinesin is known as a processive motor because

A

it remains attached to its track after each reaction cycle

38
Q

Which of the following amino acids has the most significant role in the molecular mechanisms of hemoglobin’s function?

A

histidine

39
Q

Is myosin a fibrous protein or a globular protein?

A

it’s both fibrous and globular

40
Q

Which of the following best describes the tertiary structure of myoglobin?

A

it contains heme, which is slotted into a hydrophobic pocket between alpha-helix E and alpha-helix F

41
Q

Which of the following statements about 2,3-bisphosphoglycerate (BPG) binding is FALSE?

A

BPG aids oxygen delivery to tissues by increasing the affinity of myoglobin for oxygen

42
Q

Which of the following statements about the structure of myoglobin is FALSE?

A

Myoglobin contains all three types of secondary structure

43
Q

A newly-identified protein has a sigmoidal curve in a graph of fractional saturation versus ligand concentration. What can be deduced about this protein?

A

The protein binds the ligand cooperatively

44
Q

Myoglobin and hemoglobin are both oxygen-binding proteins but have very different physiological roles. Which two of the following are the most important factors that contribute to their different functions?

A

Myoglobin is a monomeric protein, whereas hemoglobin is a tetrameric protien

Hemoglobin binds BPG which stabilizes the deoxy (T) state

45
Q

Which of the following statements most accurately explains why hemoglobin is able to deliver oxygen to myoglobin in the tissues?

A

Myoglobin has a hyperbolic oxygen binding curve, whereas hemoglobin has a sigmoidal oxygen binding curve

46
Q

Why is BPG essential for the delivery of O2 to the tissues?

A

BPG stabilizes the T state conformation of hemoglobin

47
Q

Which of the following is a role of histidine in myoglobin?

A

A histidine residue forms a hydrogen bond with oxygen

48
Q

The binding of one O2 to a molecule of hemoglobin results in:

A

An increased affinity for O2 in the remaining subunits (Which have not yet bound O2)

49
Q

Which of the following statements about the structure of myoglobin is TRUE?

A

A heme prosthetic group is tightly bound to myoglobin via coordination bond

50
Q

What is the fractional saturation of myoglobin at pO2 = 7.2 torr, if P50 = 2.8 torr?

A

0.72

51
Q

Proteins such as hemoglobin are known as ______ proteins since binding of a molecule to one site alter binding to other sites

A

allosteric

52
Q

During the formation of microfilaments, which of the following occurs?

A

ATP hydrolysis is catalyzed by F-actin

53
Q

The idea that binding of one molecule of oxygen to hemoglobin enhances further binding of oxygen to hemoglobin is called

A

cooperativity

54
Q

Proteins such as hemoglobin are known as _______ proteins since binding of a molecule of one site alter binding to other sites

A

allosteric

55
Q

When oxygen is bound to the heme group of myoglobin, it is coordinated between

A

E7 His; Fe2+ of heme

56
Q

Which allosteric effector has the greatest ability to stabilize the deoxy state of hemoglobin?

A

BPG

57
Q

What is the prominent type of secondary structure observed in myoglobin?

A

alpha-helices

58
Q

The individual hemoglobin subunits and myoglobin share what similar structures but have what different structures

A

secondary and tertiary; primary

59
Q

Which amino acid is critical for crosslinking of collagen trimers?

A

Lys

60
Q

In a muscle cell, what is the name for the bundles of myosin tails?

A

thick filaments

61
Q

Which of the following fibers is correctly paired with the protein that forms fibers

A

microfilaments: actin
microtubule: tubulin
extracellular support fibers: collagen
intermediate filaments: keratin

62
Q

Which of the following details the nucleotide-binding side when tubulin dimers assemble into microtubules?

A

the alpha site is bound to GTP; the beta site is bound to GDP

63
Q

Which of the following details the nucleotide-binding site when tubulin dimers assemble into microtubules

A

the alpha site is bout to GTP; the beta site is bound to GDP

64
Q

When a cell moves along a surface’ actin _____ occurs at the leading edge while _______ occurs at the trailing edge

A

polymerization; depolymerization

65
Q

While the composition of hemoglobin in adult humans is alpha2 beta 2, in the developing fetus, ______ is observed

A

alpha2 y2

66
Q

In a solution of high pH (<12), all of the acidic and basic sites in an amino acid are

A

deprotonated

67
Q

Parallel polypeptide chains in a beta-pleated sheet conformation are held together by

A

hydrogen bonding

68
Q

Which of the following would be a correct representation of a portion of a protein “backbone”?

A

the one with two peptide bonds on either side of an amino acid

69
Q

Which of the following best describes the peptide backbones in a beta-sheet?

A

highly extended

70
Q

Glycine, the simplest amino acid, is different from all of the other standard amino acids in that it

A

does not have a chiral center

71
Q

The first step in the folding of disordered polypeptide chains into stable proteins is the formation of:

A

secondary structural elements

72
Q

Which one of these characteristics is not true for the alpha helix?

A

there is a requirement for glycine every third amino acid residue

73
Q

Which of the following amino acids is most likely to be found on the interior of a protein (Use the Hydrophobic Scale from your textbook)

A

methionine

74
Q

Molecular chaperones assist proteins in the formation of

A

tertiary structure

75
Q

Which of the following amino acids would be classified as a polar neutral amino acid?

A

The amino acid that has a neutral charge

76
Q

What enzyme is required to form a new phosphodiester bond when inserting DNA into a plasmid?

A

ligase

77
Q

Which bond is unable to rotate?

A

peptide bond

78
Q

Which of the following has the most dramatic influence on the characteristics of an individual natural protein:

A

the amino acid sequence

79
Q

Which of the following is a palindromic sequence?

A

GAATTC

80
Q

Which of the following statements concerning the tripeptide Val-Ala-Gly is correct?

A

The C-terminal amino acid residue is Gly

Genetics Tuskegee (8 decks)

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