Problem Set for Exam 1

What is the optimal angle formed by the three atoms, N, H, and O in a hydrogen bond between an amide (N-H) and a carbonyl oxygen (C=O)?

180°

Identify the hydrogen bond donors and hydrogen bond acceptors below.

A is donor, B is acceptor: C is acceptor, D is donor

Which of the following is FALSE regarding the activity of ATCase?

ATP favors the T state of ATCase

Which of the following best describes an antibiotic treatment containing an adjuvant and an antibiotic compound?

Amoxicillin inhibits β-lactamase, enabling clavulanic acid to inhibit glycopeptide transpeptidase

Which amino acid is charged at neutral pH? (pH = 7)

Asp

Rank the following molecular interactions from strongest to weakest.

Covalent bonds > Hydrogen bonds > Van Der Waals

Which of the following correctly describes the flow of genetic information

DNA is transcribed to RNA which is translated to Protein

Which of the following is not a function or property of lipids?

Determine in the size and shape of a cell

Which statement about an enzyme-catalyzed reaction is TRUE?

Enzymes decrease the activation energy of the conversion of the substrate to the product

In the catalytic triad of chymotrypsin, which statement is TRUE?

His57 acts to position the Ser195 hydroxyl group with respect to the peptide linkage of the substrate, so that serine side chain can attack the peptide bond. His57 also acts as a general base catalyst to accept the Ser195 hydroxyl proton during the nucleophilic attack

Which of the following conditions promote the release of oxygen from hemoglobin?

Increased 2,3-BPG concentration, Increased CO2 concentration, decreased pH

The substrate specificity pocket in chymotrypsin...

Is a binding site that recognizes the large hydrophobic side chain of the residue preceding the peptide bond to be hydrolyzed

Which amino acid side chain does not form hydrogen bonds?

Leu

Which of the following statements about the Bohr effect is TRUE?

Lower pH values and higher concentrations of CO2 favor the T state

Which of the following is FALSE regarding important properties of an effective drug?

Must be oxidized by cytochrome P450 enzymes to increase half-life and decrease rate of excretion

Which of the following is an example of tertiary protein structure?

Myoglobin which is composed of α-helices in its structure

Which of the following can be found within a prokaryotic cell?

Nucleoid

If the sulfhydryl groups of two Cysteines in a polypeptide chain are__________, they can form a___________.

Oxidized/disulfide bond

Which of the following is NOT correct concerning the oxygenation plot of protein X and Y shown below?

Protein X exhibits cooperative binding, whereas Y does not

Which of the following characteristics is not shared between both hemoglobin and myoglobin?

Quaternary structure

The main function of the oxyanion hole is to...

Stabilize the negatively charged ion formed during the transition state of the tetrahedral intermediate

Which of the following statements about the Michaelis constant KM is TRUE?

The Km is equal to the substrate concentration when the reaction rate is half its maximal value

Which of the following IS NOT assumed in Michaelis-Menten kinetics?

The Km is the concentration of enzyme when the rate is ½ Vmax

True or False: The trans conformation of the peptide bond is favored for most polypeptides

True

You have obtained the following data for enzyme activity measured in the presence of an inhibitor, identify the type of inhibition indicated.

Uncompetitive reversible inhibition

Many extracellular proteins are resistant to denaturation due to which of the following interactions?

disulfide bonds

Which of the following values would be most appropriate for comparing the efficiencies by which an enzyme catalyzes the same reaction with two different substrates?

kcat/Km

What best describes the reason why penicillin is an irreversible inhibitor of glycopeptide transpeptidase?

the inhibitor forms a covalent bond to a residue in the enzyme active site.

HA is a weak acid with a pKa = 5.5. What percent of the acid (HA) is present at pH 4.5? Henderson-Hasselbalch Equation = pH = pKa + log([A-]/[HA])

∼ 10%