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BIOC MIDTERM PRACTICE POOL MCQs > ALL > Flashcards

ALL Flashcards

1
Q
  1. The central dogma of molecular biology describes how:
A

B. the message contained in the DNA is transcribed to mRNA and translated to protein.

Example sentence: The central dogma explains the flow of genetic information from DNA to protein.

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2
Q
  1. The function of a protein is determined by its:
A

A. three-dimensional shape.

Example sentence: A protein’s function is closely related to its unique three-dimensional structure.

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3
Q
  1. The sequence of what in a protein determines how it folds?
A

B. Amino acids.

Example sentence: The specific sequence of amino acids in a protein dictates its final folded structure.

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4
Q
  1. Why might a biochemist make a particular protein in the laboratory?
A

D. All the above.

Example sentence: Biochemists may produce proteins for various purposes such as research, medical applications, or industrial use.

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5
Q
  1. Proteins are polymers of:
A

D. amino acids linked together by peptide covalent bonds.

Example sentence: Proteins are composed of long chains of amino acids connected by peptide bonds.

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6
Q
  1. What level(s) of protein structure(s) are stabilized with PRIMARILY hydrogen bonds?
A

B. Secondary.

Example sentence: Secondary protein structures, like alpha helices and beta sheets, are mainly stabilized by hydrogen bonds.

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7
Q
  1. Which statement regarding hydrogen bonds is INCORRECT?
A

D. Hydrogen bonds stabilize the primary sequence of amino acids.

Example sentence: Hydrogen bonds play a crucial role in maintaining the secondary and tertiary structures of proteins.

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8
Q
  1. Which statement about protein secondary structure is CORRECT?
A

C. Turns, loops and coils connect beta strands and alpha helices together.

Example sentence: Secondary protein structures are connected by turns, loops, and coils.

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9
Q
  1. In proteins, supersecondary structures are:
A

B. structural features that have more than one secondary structural element.

Example sentence: Supersecondary structures are combinations of secondary structural elements in proteins.

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10
Q
  1. Which forms of the alpha-amino and alpha-carboxyl groups of alanine are most likely to occur at very high pH (for the free amino acid)?
A

B. NH2 and COO-.

Example sentence: At high pH, the amino and carboxyl groups of alanine are likely to be in their deprotonated forms.

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11
Q
  1. The amino acid pictured below:
A

A. is likely to be found in the hydrophobic core of a protein.

Example sentence: Hydrophobic amino acids are often located in the interior of proteins.

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12
Q
  1. Which one of the following statements about the amino acid (cysteine, at neutral pH) shown below is CORRECT?
A

D. It can be involved in forming a type of post-translational modification called disulfide bonds.

Example sentence: Cysteine residues can form disulfide bonds, a common post-translational modification.

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13
Q
  1. Amino acid side chain modification such as:
A

A. phosphorylation is commonly used to control enzyme activity, like an ON/OFF switch.

Example sentence: Phosphorylation of amino acid side chains can regulate enzyme activity.

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14
Q
  1. An alpha helix in a protein contains:
A

C. 3.6 amino acids per turn, does not normally contain proline and is often polar on one side and non-polar on the other side.

Example sentence: Alpha helices exhibit a characteristic structure with specific amino acid patterns.

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15
Q
  1. Which statement about beta turns is INCORRECT?
A

B. They connect individual polypeptides.

Example sentence: Beta turns facilitate changes in protein directionality within the same polypeptide chain.

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16
Q
  1. EDHWVNQYSAIT is an amino acid sequence that can form an alpha helix. Which residues are involved in forming a hydrogen bond with residue Q (underlined)?
A

D. H and T.

Example sentence: Specific amino acid residues in a sequence can interact through hydrogen bonding to stabilize protein structures.

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17
Q
  1. The four main classifications of amino acids, based on the properties of their side chains, are:
A

A. non-polar, polar uncharged, polar positively charged, polar negatively charged.

Example sentence: Amino acids can be categorized into different groups based on the nature of their side chains.

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18
Q
  1. The peptide bond in proteins is:
A

A. planar.

Example sentence: Peptide bonds exhibit a planar configuration due to partial double bond character.

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19
Q
  1. Which one of the following statements about protein structure is INCORRECT?
A

A. Beta-sheets are stabilized by hydrogen bonds between carbonyl oxygens and amino hydrogens from amino acids that are next to each other on the same beta-strand.

Example sentence: Beta-sheets are primarily stabilized by hydrogen bonds between adjacent strands, not within the same strand.

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20
Q
  1. What is the main driving force in protein folding?
A

C. Hydrophobic core formation.

Example sentence: The burial of hydrophobic residues drives the folding of proteins into their native structures.

21
Q
  1. An enzyme catalyzed reaction:
A

B. has a lower activation energy than the equivalent uncatalyzed reaction.

Example sentence: Enzymes lower the activation energy required for chemical reactions to occur.

22
Q
  1. Which statement about the role of enzymes in cellular metabolism is INCORRECT?
A

B. Enzymes ensure that all chemical reactions are at equilibrium.

Example sentence: Enzymes catalyze reactions in cells without altering the equilibrium state.

23
Q
  1. Pyridoxal phosphate (PLP) is present in the active site of glycogen phosphorylase, where it acts as a(n):
A

C. Coenzyme.

Example sentence: Pyridoxal phosphate functions as a coenzyme in the active site of certain enzymes.

24
Q
  1. What enables enzymes to bind to substrates very selectively?
A

A. The 3D geometry and chemical properties of the active site.

Example sentence: Enzymes exhibit specificity in substrate binding due to the unique features of their active sites.

25
Q
  1. Which effect below does NOT contribute to enzymatic catalysis?
A

B. Irreversible binding of substrates to the active site.

Example sentence: Irreversible binding of substrates would hinder enzymatic turnover and catalysis.

26
Q
  1. Enzymes usually bind BEST to:
A

C. the transition state of the reaction catalyzed.

Example sentence: Enzymes exhibit high affinity for the transition state of the reaction they catalyze.

27
Q
  1. The active site of an enzyme:
A

C. includes amino acid sidechains that specifically bind substrate through multiple weak interactions.

Example sentence: The active site of an enzyme contains residues that interact with the substrate through various non-covalent interactions.

28
Q
  1. Vmax is the maximum rate of reaction an enzyme can catalyze when:
A

A. saturated with substrate.

Example sentence: Vmax represents the maximum rate of an enzyme-catalyzed reaction under conditions of substrate saturation.

29
Q
  1. In enzyme kinetics, a progress curve:
A

B. shows the appearance of product or disappearance of substrate, over time.

Example sentence: Progress curves in enzyme kinetics provide information on the rate of product formation or substrate consumption.

30
Q
  1. Which one of the following statements about enzyme kinetics is INCORRECT?
A

B. The Vmax of a reaction will not change if more enzyme is added.

Example sentence: Increasing enzyme concentration can raise the Vmax of a reaction due to enhanced catalytic efficiency.

31
Q
  1. A Lineweaver-Burk plot for an enzyme-catalyzed reaction is shown below. The point labeled (y) on the plot corresponds to:
A

C. -1/Km

Example sentence: In a Lineweaver-Burk plot, the y-intercept corresponds to the reciprocal of Vmax.

32
Q
  1. Below is a plot that shows an enzymatic reaction with and without an inhibitor. The inhibitor used in the experiment above is a:
A

B. competitive inhibitor because it increases KM.

Example sentence: Competitive inhibitors compete with the substrate by binding to the active site and raising the apparent KM.

33
Q
  1. An enzyme-catalyzed reaction in the presence of a competitive inhibitor:
A

D. can achieve the same Vmax as the uninhibited enzyme if given enough substrate.

Example sentence: Competitive inhibitors can be overcome by providing higher substrate concentrations to reach the same maximum reaction rate.

34
Q
  1. In the presence of a non-competitive inhibitor, Vmax
A
35
Q

labeled (y) on the plot corresponds to:

A

C. Vmax.

Example sentence: The point labeled (y) on the plot corresponds to the maximum velocity of the reaction.

36
Q

Below is a plot that shows an enzymatic reaction with and without an inhibitor. The inhibitor used in the experiment above is a:

A

B. competitive inhibitor because it increases KM.

No additional information.

37
Q

An enzyme-catalyzed reaction in the presence of a competitive inhibitor:

A

D. can achieve the same Vmax as the uninhibited enzyme if given enough substrate.

No additional information.

38
Q

In the presence of a non-competitive inhibitor, Vmax will:

A

D. decrease, while KM will remain unchanged.

No additional information.

39
Q

Which statement about the glycogen phosphorylase enzyme is INCORRECT:

A

B. Glycogen phosphorylase is activated by directly binding to insulin.

No additional information.

40
Q

Myoglobin:

A

A. can bind one oxygen molecule.

No additional information.

41
Q

Proteins that show cooperativity:

A

C. Favour the R-state at high [S] (substrate concentration).

No additional information.

42
Q

The T-state of hemoglobin is stabilized by:

A

A. Binding of bisphosphoglycerate (BPG) between subunits.

No additional information.

43
Q

Hemoglobin displays a sigmoidal oxygen binding curve because the binding of oxygen:

A

C. to one subunit can change the conformation of the other subunits.

No additional information.

44
Q

2,3-bisphosphoglycerate (BPG):

A

D. binds allosterically to stabilize the T-state of hemoglobin.

No additional information.

45
Q

What connects allosteric control and cooperativity?

A

A. Both give rise to a sigmoidal activity curve.

No additional information.

46
Q

Which of the following is a chemical substance that activates a receptor?

A

A. Agonist.

No additional information.

47
Q

Which of the following is a chemical substance that prevents the activation of a receptor by an agonist?

A

A. Antagonist.

No additional information.

48
Q

Fill in the blank with the best option: Antagonist is to receptor as _______ is to enzyme.

A

A. Inhibitor.

No additional information.

BIOC MIDTERM PRACTICE POOL MCQs (2 decks)

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