ALL Flashcards
- The central dogma of molecular biology describes how:
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.
- The function of a protein is determined by its:
A. three-dimensional shape.
Example sentence: A protein’s function is closely related to its unique three-dimensional structure.
- The sequence of what in a protein determines how it folds?
B. Amino acids.
Example sentence: The specific sequence of amino acids in a protein dictates its final folded structure.
- Why might a biochemist make a particular protein in the laboratory?
D. All the above.
Example sentence: Biochemists may produce proteins for various purposes such as research, medical applications, or industrial use.
- Proteins are polymers of:
D. amino acids linked together by peptide covalent bonds.
Example sentence: Proteins are composed of long chains of amino acids connected by peptide bonds.
- What level(s) of protein structure(s) are stabilized with PRIMARILY hydrogen bonds?
B. Secondary.
Example sentence: Secondary protein structures, like alpha helices and beta sheets, are mainly stabilized by hydrogen bonds.
- Which statement regarding hydrogen bonds is INCORRECT?
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.
- Which statement about protein secondary structure is CORRECT?
C. Turns, loops and coils connect beta strands and alpha helices together.
Example sentence: Secondary protein structures are connected by turns, loops, and coils.
- In proteins, supersecondary structures are:
B. structural features that have more than one secondary structural element.
Example sentence: Supersecondary structures are combinations of secondary structural elements in proteins.
- 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)?
B. NH2 and COO-.
Example sentence: At high pH, the amino and carboxyl groups of alanine are likely to be in their deprotonated forms.
- The amino acid pictured below:
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.
- Which one of the following statements about the amino acid (cysteine, at neutral pH) shown below is CORRECT?
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.
- Amino acid side chain modification such as:
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.
- An alpha helix in a protein contains:
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.
- Which statement about beta turns is INCORRECT?
B. They connect individual polypeptides.
Example sentence: Beta turns facilitate changes in protein directionality within the same polypeptide chain.
- 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)?
D. H and T.
Example sentence: Specific amino acid residues in a sequence can interact through hydrogen bonding to stabilize protein structures.
- The four main classifications of amino acids, based on the properties of their side chains, are:
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.
- The peptide bond in proteins is:
A. planar.
Example sentence: Peptide bonds exhibit a planar configuration due to partial double bond character.
- Which one of the following statements about protein structure is INCORRECT?
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.
- What is the main driving force in protein folding?
C. Hydrophobic core formation.
Example sentence: The burial of hydrophobic residues drives the folding of proteins into their native structures.
- An enzyme catalyzed reaction:
B. has a lower activation energy than the equivalent uncatalyzed reaction.
Example sentence: Enzymes lower the activation energy required for chemical reactions to occur.
- Which statement about the role of enzymes in cellular metabolism is INCORRECT?
B. Enzymes ensure that all chemical reactions are at equilibrium.
Example sentence: Enzymes catalyze reactions in cells without altering the equilibrium state.
- Pyridoxal phosphate (PLP) is present in the active site of glycogen phosphorylase, where it acts as a(n):
C. Coenzyme.
Example sentence: Pyridoxal phosphate functions as a coenzyme in the active site of certain enzymes.
- What enables enzymes to bind to substrates very selectively?
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.
- Which effect below does NOT contribute to enzymatic catalysis?
B. Irreversible binding of substrates to the active site.
Example sentence: Irreversible binding of substrates would hinder enzymatic turnover and catalysis.
- Enzymes usually bind BEST to:
C. the transition state of the reaction catalyzed.
Example sentence: Enzymes exhibit high affinity for the transition state of the reaction they catalyze.
- The active site of an enzyme:
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.
- Vmax is the maximum rate of reaction an enzyme can catalyze when:
A. saturated with substrate.
Example sentence: Vmax represents the maximum rate of an enzyme-catalyzed reaction under conditions of substrate saturation.
- In enzyme kinetics, a progress curve:
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.
- Which one of the following statements about enzyme kinetics is INCORRECT?
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.
- A Lineweaver-Burk plot for an enzyme-catalyzed reaction is shown below. The point labeled (y) on the plot corresponds to:
C. -1/Km
Example sentence: In a Lineweaver-Burk plot, the y-intercept corresponds to the reciprocal of Vmax.
- Below is a plot that shows an enzymatic reaction with and without an inhibitor. The inhibitor used in the experiment above is 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.
- An enzyme-catalyzed reaction in the presence of a competitive inhibitor:
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.
- In the presence of a non-competitive inhibitor, Vmax
labeled (y) on the plot corresponds to:
C. Vmax.
Example sentence: The point labeled (y) on the plot corresponds to the maximum velocity of the reaction.
Below is a plot that shows an enzymatic reaction with and without an inhibitor. The inhibitor used in the experiment above is a:
B. competitive inhibitor because it increases KM.
No additional information.
An enzyme-catalyzed reaction in the presence of a competitive inhibitor:
D. can achieve the same Vmax as the uninhibited enzyme if given enough substrate.
No additional information.
In the presence of a non-competitive inhibitor, Vmax will:
D. decrease, while KM will remain unchanged.
No additional information.
Which statement about the glycogen phosphorylase enzyme is INCORRECT:
B. Glycogen phosphorylase is activated by directly binding to insulin.
No additional information.
Myoglobin:
A. can bind one oxygen molecule.
No additional information.
Proteins that show cooperativity:
C. Favour the R-state at high [S] (substrate concentration).
No additional information.
The T-state of hemoglobin is stabilized by:
A. Binding of bisphosphoglycerate (BPG) between subunits.
No additional information.
Hemoglobin displays a sigmoidal oxygen binding curve because the binding of oxygen:
C. to one subunit can change the conformation of the other subunits.
No additional information.
2,3-bisphosphoglycerate (BPG):
D. binds allosterically to stabilize the T-state of hemoglobin.
No additional information.
What connects allosteric control and cooperativity?
A. Both give rise to a sigmoidal activity curve.
No additional information.
Which of the following is a chemical substance that activates a receptor?
A. Agonist.
No additional information.
Which of the following is a chemical substance that prevents the activation of a receptor by an agonist?
A. Antagonist.
No additional information.
Fill in the blank with the best option: Antagonist is to receptor as _______ is to enzyme.
A. Inhibitor.
No additional information.
