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Biochemistry > Finals quizes > Flashcards

Finals quizes Flashcards

1
Q

The information needed for the structure of a protein is contained in

A

primary structure

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2
Q

Which of the following pairs of amino acid is present at position 3 and 8, respectively of the protein hormone oxytocin?
a. Cysteine and arginine
b. Isoleucine and leucine
c. Isoleucine and histidine
d. Phenylalanine and arginine

A

Isoleucine and leucine

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3
Q

Which of the following amino acids is present in the insulin structure of both cows and pigs but not in human?
a. Isoleucine
b. Alanine
c. Threonine
d. Serine

A

Alanine

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4
Q

Which of the following is an incorrect characterization for the protein hemoglobin?
a. conjugated protein
b. simple protein
c. multimeric protein
d. globular protein

A

simple protein

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5
Q

In the tetrapeptide Phe-Gln-Trp-His, the C-terminal amino acid is

A

Histidine

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6
Q

When a disulfide bond is formed by two cysteine molecules, the amino acids containing this new linkage has been

A

oxidized

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6
Q

The protein found in milk?

A

casein

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7
Q

The pKa values of the alpha carboxyl groups of common amino acids are around

A

pH 2

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8
Q

The pKa values of the amino groups of common amino acids are around ___.

A

pH 9

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9
Q

The protein that transport fatty acids in blood?

A

serum albumin

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9
Q

In electrophoresis experiments

A

an electric field must be applied to the mixture to be separated

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10
Q

Which of the following statements regarding hydrogen bonding in secondary structures is TRUE?
a. a-helices only use intrachain hydrogen bonds and b-sheets can use either intrachain or interchain hydrogen bonds.
b. Both a-helices and b-sheets only use interchain hydrogen bonds.
c. a-helices can use either intrachain or interchain hydrogen bonds and b-sheets only use interchain hydrogen bonds.
d. Both a-helices and b-sheets only use intrachain hydrogen bond

A

a.
a-helices only use intrachain hydrogen bonds and b-sheets can use either intrachain or interchain hydrogen bonds.

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10
Q

Carnosine functions as an antioxidant in the skeletal muscles and a dipeptide made of:

A

alanine and histidine

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11
Q

The a-keratin chains indicated by the diagram below have undergone one chemical step. To alter the shape of the a-keratin chains–as in hair waving–what subsequent steps are required?

A

chemical reduction and then chemical oxidation

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12
Q

If an amino acid has an isoelectric point of 3.44, what will happen to the structure of amino and carboxyl group when it is placed in a solution at pH 10.5?

A

c.
the proton concentration is low (H+), and so the amino group will be uncharged while the carboxyl group is deprotonated.

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12
Q

Hydrophobic interactions may occur between the R groups of which of the following amino acids?
a. valine and asparagine
b. phenylalanine and tryptophan
c. arginine and histidine
d. tyrosine and glycine

A

phenylalanine and tryptophan

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12
Q

The non-amino acid portion of a conjugated protein is called a

A

prosthetic group

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13
Q

In sickle-cell anemia, which amino acid residue in hemoglobin structure is replaced?

A

glutamic acid

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13
Q

Which of the following is NOT a factor that tends to destabilize a-helices?
a. presence of a secondary amino acids in the protein
b. clusters of amino acids with stronger hydrogen bonds
c. clusters of amino acids with bulky R-groups
d. clusters of amino acids with similarly charged R-groups

A

b.
clusters of amino acids with stronger hydrogen bonds

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13
Q

Which group consists only of amino acids with carboxylate side chains?

A

aspartate and glutamate

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14
Q

Which of the following agents can disrupt hydrophobic interactions in a protein structure?
a. heavy metals
b. ethanol
c. detergent
d. Heat

A

c.
detergent

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14
Q

In a solution of high pH, all of the acidic sites in an amino acid are

A

deprotonated

15
Q

What happens when a protein is denatured?

A

Its secondary structure is disrupted but its primary structure remains intact.

15
Q

Which of the following is the most common function for fibrous proteins?

a.
structural roles

b.
carrier molecules

c.
enzymes

d.
transport molecules

A

a.
structural roles

15
Q

Which of the following amino acids is unlikely to be found in an a-helix due to its cyclic structure?
a. Tryptophan
b. Lysine
c. Phenylalanine
d. Proline

A

d.
Proline

16
Q

T or F
In zymogen activation, an inactive protein is converted to an active one by creating a cleavage.

A

TRUE

16
Q

A child with tall stature, loose joints, and detached retinas is found to have a mutation in collagen. Which of the following amino acids is the recurring amino acid most likely to be altered in mutations that distort collagen molecules?

A

glycine

16
Q

Penicillin causes inhibition of bacterial cell wall synthesis by interfering with the cross-linking of peptidoglycans. Which of the following enzymes is inhibited by this antibiotic?
a. pteridine
b. transpeptidase
c. transaminase
d. DNA gyrase

A

b.
transpeptidase

17
Q

Which of the following is a DNA gyrase inhibitor, thus disrupting bacterial DNA replication?
a. sulfanilamide
b. ciprofloxacin
c. tetracyclines

A

b.
ciprofloxacin

17
Q

Which of the following is an advantage of lowering the activation energy?
a. it allows reactions to proceed more quickly
b. it changes the optimum pH of the enzyme
c. it allows chemicals to react slowly
d. it allows reactions to proceed beyond the optimum temperature

A

a.
it allows reactions to proceed more quickly

17
Q

Which of the following extremophiles can thrive in a high salinity environment?
a. Cryophiles
b. Halophiles
c. Alkaliphiles
d. Thermophiles

A

b.
Halophiles

17
Q

All of the following statements about NAD+ are true, EXCEPT?
a. It is a cofactor to many dehydrogenase enzymes
b. It can be used to reduce pyruvate to lactate
c. It accepts hydride ions and becomes NADH when oxidizing substrates
d. It Is synthesized from the vitamin niacin

A

b.
It can be used to reduce pyruvate to lactate

17
Q

Which strategies below can be effective in preventing antibiotic resistance?

a. When an antibiotic is needed, do not consider a medication prescribed by someone else instead seek professional help from doctors.
b. When prescribed with antibiotics, only take it until you feel better so that you limit the number of doses you take.

A

a.
When an antibiotic is needed, do not consider a medication prescribed by someone else instead seek professional help from doctors.

17
Q

T or F
ACE inhibitors stop the activity of ACE, thus narrowing the passage of blood vessels.

A

TRUE

17
Q

Which of the following statements is FALSE?
a. Some coenzymes are prosthetic groups
b. Some metal ions are cofactors
c. All vitamins are cofactors

A

c.
All vitamins are cofactors

18
Q

An enzyme active site is a location in the enzyme where:

A

The actual catalysis occurs.

18
Q

Which of the following statements concerning the effect of temperature change on an enzyme-catalyzed reaction is incorrect?
a. none of the choices
b. An increase in temperature to the optimum temperature maximizes reaction rate.
c. An increase in temperature can increase the reaction rate by increasing the speed at which molecules move.

A

a.
none of the choices

19
Q

In which of the following is the pairing between enzyme type and enzyme function incorrect?
a. dehydrogenase - removal of water from substrate
b. oxidase - oxidation of a substrate
c. isomerase - conversion of one structural isomer into another
d. carbohydrases - hydrolysis of glycosidic bonds in carbohydrates

A

a.
dehydrogenase - removal of water from substrate

20
Q

Which of the enzymes does NOT exhibit linkage specificity?
a. lipase
b. amylase
c. peptidase
d. catalase

A

d.
catalase

20
Q

Which of the following enzymes cleaves the peptide bonds?
a. hexokinase
b. catalase
c. pepsinogen
d. phosphatase
e. chymotrypsin

A

e.
chymotrypsin

21
Q

ATP is a negative allosteric effector for glycogen phosporylase. This is an example of

A

a.
feedback inhibition

22
Q

Which of the following is NOT true about B vitamins?
a. They are usually water soluble
b. Niacin and riboflavin are examples
c. They are important in many metabolic reactions
d. They are usually fully active in the form when we eat them

A

d.
They are usually fully active in the form when we eat them

22
Q

Which of the following drugs acts as a noncompetitive inhibitor?
a. sulfanilamide
b. penicillin
c. lisinopril
d. CIPRO

A

d.
CIPRO

23
Q

Analyze each sentence and choose the correct answer.

(1) The B vitamins serve as precursors for enzyme cofactors.
(2) Allosteric enzyme actions are associated with the regulation of enzyme activity
(3) In a covalent modification, the addition of the phosphate group may only deactivate an enzyme.

a. Two of the three statements are true.
b. None of the statements is true.
c. Only one of the statements is true.
d. All three statements are true.

A

a.
Two of the three statements are true.

23
Q

A noncompetitive inhibitor

A

binds to the enzyme at a site other than the active site

24
Q

An enzyme that catalyzes the oxidation of only one kind of alcohol would be described as showing:
a. absolute specificity
b. group specificity
c. stereochemical specificity
d. linkage specificity

A

a. absolute specificity

25
Q

Can be synthesized in the body from methionine (both contain sulfur)
* Responsible for reducing the action of glutathione

A

Cysteine

25
Q

Storage and transport form of ammonia
Removal of ammonia from brain
Precursor of purines and pyrimidines

A

Glutamine

25
Q

proteins that act as a catalyst for biochemical reactions.

A

Enzymes

25
Q

essential component of collagen and is important for the proper functioning of joints and tendons.
* helps maintain and strengthen heart muscles.

A

Proline

26
Q
  • naturally-occurring, unbranched polymer in which the monomer units are amino acids
A

PROTEIN

27
Q
A
28
Q
A

Biochemistry (4 decks)

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