BCH3023C Exam 1 Practice Questions

In deoxy hemoglobin (Hb), the FE (II) is coordinated to: A. Four nitrogens of heme, and the proximal His B. Four nitrogens of heme and to a water molecule C. Two nitrogens of heme and to three His residues in Hb D. Two nitrogens of heme and to three water molecules

A. Four nitrogens of heme, and the proximal His

Which of the following statement is INCORRECT? A. Hemoglobin and myoglobin are the two oxygen binding proteins B. Hemoglobin transports O2 in the blood C. Myoglobin stores O2 in muscles D. None of the above

A. Hemoglobin and myoglobin are the two oxygen binding proteins

Collagen contains large amounts of which ONE of the following? A. Inter-chain hydrogen bonds B. Intra-chain hydrogen bonds C. B-sheet D. a-helix

A. Inter-chain hydrogen bonds

Which ONE of the following amino acid substitutions most likely causes a change in a protein's tertiary structure? A. Isoleucine to arginine B. Arginine to lysine C. Valine to leucine D. Threonine to serine E. Asparagine to glutamine

A. Isoleucine to arginine

Which would be best to separate a protein that binds strongly to its substrate? A. Gel filtration B. Affinity chromatography C. Cation exchange D. Anion exchange E. Cation or anion exchange

B. Affinity chromatography

Which of the following describes the side chain of valine? A. Contains a sulfhydryl group B. Contains a branched chain hydrocarbon C. Contains an aromatic ring D. Doesn't have a side chain E. Contains an acidic side chain

B. Contains a branched chain hydrocarbon

Which of the following does not contribute to the tertiary structure of a protein? A. Hydrogen bonds between side chains of amino groups B. Hydrogen bonds between amine and carbonyl groups in the peptide backbone C. Disulfide bonds between cysteine residues D. Hydrophobic interactions between side chains of amino acids E. Salt bridges between ionized groups in side chains of amino acids

B. Hydrogen bonds between amine and carbonyl groups in the peptide backbone

The most important buffering system for maintaining proper blood pH is: A. The charges on the amino acids B. The bicarbonate buffer system of CO2, carbonic acid, and bicarbonate C. Phosphate groups of serum phosphoproteins D. None of the above E. All of the above

B. The bicarbonate buffer system of CO2, carbonic acid, and bicarbonate

In a regular alpha helix: A. Side chain residues point up and down the axis of the helix B. The helix is right-handed C. There are five residues per helical turn D. The oxygen of the carbonyl carbon in a peptide bond points out toward the exterior of the helix E. There are usually many proline residues present

B. The helix is right-handed

In proteins, the side chain R-groups of serene and asparagine generally form __ bonds with each other A. Covalent B. Ionic C. Hydrogen D. Hydrophobic E. Peptide

C. Hydrogen

Which is true regarding the orientation of the R-groups in beta structures? A. In the parallel beta sheet structures the amino acid R-groups are all on the same side of the sheet B. In the antiparallel beta sheet structure the R-groups on alternate strands are on the same side of the sheet C. In parallel and antiparallel sheets consecutive R-groups on each peptide strand are on alternate sides of the sheet D. Because of the free rotation around the alpha carbon, the R-groups can seek the least crowded region and are not restricted to a specific side of the sheet E. a and b

C. In parallel and antiparallel sheets consecutive R-groups on each peptide strand are on alternate sides of the sheet

Under which ONE of the following conditions would hemoglobin have the highest affinity for oxygen? A. High bisphosphoglycerate and high pH B. High bisphosphoglycerate and low pH C. Low bisphosphoglycerate and high pH D. Low bisphosphoglycerate and low pH E. Low bisphosphoglycerate and low pH and high CO

C. Low bisphosphoglycerate and high pH

An octapeptide composed of four repeating glyclalanyl units has: A. One free amino group on an alanyl residue B. One free amino group on an alanyl residue and one free carboxyl group on a glycyl residue C. One free amino group on a glycyl residue and one free carboxyl group on an alanyl residue D. Two free amino and two free carboxyl groups E. Two free carboxyl groups, both on glycyl residues

C. One free amino group on a glycyl residue and one free carboxyl group on an alanyl residue

Which of the following does not describe hemoglobin? A. Hemoglobin is an oxygen transport protein B. Hemoglobin is an allosteric protein C. Hemoglobin has quaternary structure D. Copper ions are important in hemoglobin's ability to bind oxygen E. Hemoglobin is composed, in part, of an iron containing heme group

D. Copper ions are important in hemoglobin's ability to bind oxygen

Disulfide bonds form ____. A. Before a protein folds into its native conformation B. Half way through the protein folding process C. Only between cysteine on the same polypeptide chain D. Only after the protein has been folded into its native conformation

D. Only after the protein has been folded into its native conformation

Chaperone proteins: A. Bind newly synthesized polypeptides and assist in proper folding B. Increase the rate of correct folding and prevent the formation of incorrectly folded intermediates C. Bind to unassembled protein subunits to prevent incorrect aggregation before they are assembled into a multisubunit protein D. Statements A, B and C

D. Statements A, B and C

Collagen is best described as A. an a-helical structural protein B. a coiled-coil found in hair C. a cross-linked globular protein D. a triple-helical fibrous protein

D. a triple-helical fibrous protein

Given the following 5 amino acids, which ONE of them is the most hydrophilic? A. serine B. asparagine C. methionine D. arginine E. glycine

D. arginine

The isoelectronic point of an amino acid is the point where: A. The pK of the carboxylic acid is the same as the amino group B. Sodium ions are attracted to the amino groups C. The solubility of the amino acid is maximized D. The amino acid racemizes E. The amino acid carries no net electrical charge

E. The amino acid carries no net electrical charge

Given the following 5 amino acids, which ONE has the bulkiest side chain? A. alanine B. valine C. tyrosine D. histidine E. tryptophan

E. tryptophan