Biochemistry (Chapter 3)

If gly has a positive charge in a buffer at pH 1 then gly-gly-gly in the same buffer should have which of the following charges?

+1

Gly Gln Ser Lys Met Thr Asp Asn Tyr. What is the net charge of this peptide at pH 7?

0

Which of the following groups of amino acid residues would be expected to have all of their side chains in charged state at physiological pH?

Arg; Asp; Lys

Which of the following is not a feature of collagen?

Beta-pleated sheet secondary structure

Which of the following describes the side chain of glutamine?

Contains an amide

Which of the following describes the side chain of phenylalanine?

Contains an aromatic ring

Which of the following describes the side chain of leucine?

Contains an branched chain hydrocarbon

Which of the following statements about cysteine is true?

Cysteine is two cysteine molecules covalently attached by a disulfide bridge.

Which of the following characterizes L-lysine?

Diamino monocarboxylic amino acid

Which of the following amino acids has more than one carboxyl group?

Glutamic acid

Amino acids are classified according to the nature of their side chain. All of the following amino acids are correctly classified EXCEPT:

Histidine: nonpolar and uncharged

Which of the following is responsible for the maintenance of protein secondary structure?

Hydrogen bonds

What is the nature of the usual linkage between nucleic acids and histones in nucleoproteins?

Ionic linkages between phosphoric acid of nucleic acids and basic amino acids of proteins.

Which of the following amino acid residues may participate in strong hydrophobic bonding?

Isoleucine

Which statement below is most correct regarding the alpha helical structure of polypeptide chains in proteins?

It is primarily dependent upon hydrogen bonding

Which amino acid contains a sulfur atom?

Methionine

Which of the following amino acids will terminate an alpha helical structure in globular proteins?

Proline

Which of the mutations would you expect to cause the most drastic alteration in the functional performance of a polypeptide chain?

Replacement of glutamate with lysine

To which of the following does protein tertiary structure refer?

The 3-D structure

Which of the following statements about protein structure is correct?

The folding of the polypeptide into a globular structure results in an interior enriched with hydrophobic amino acids

Which of the following amino acids would be considered the MOST polar?

Threonine

From the following list select an amino acid with a side chain having strong UV-absorbing power.

Tryptophan

Collagen is a protein whose conformation is characterized by

a triple helix.

The major functional groups present in collagen which are directly involved in the formation of crosslinks are

aldehydes derived from lysine

The primary structure of a protein refers to its

amino acid sequence

In a simple protein molecule in an aqueous solution the charged groups,

are almost all on the surface

The primary sequence of proteins is best described by the statement that proteins

are polymers formed by amide linkages between the carboxyl and alpha-amino groups of alpha-amino acids

Which amino acid possesses a guanidinium group in the side chain?

arginine

An amino acid containing an amide function in its side chain:

asparagine

The amino acid side-chain which most commonly interacts to form covalent bonds in proteins

contains a sulfhydryl group

Which of the following describes the side chain of serine?

contains an alcoholic group

The formation of a peptide bond between two amino acids

creates partial double-bond character among three atoms

Identify in the following list the covalent bond commonly found in proteins

disulfide bond

Which interaction may participate in the stabilization of tertiary structure by covalently linking different polypeptide chains

disulfide bond

The 3-D structures of a protein is maintained by

disulfide linkages; hydrophobic bonds; hydrogen bonds; ionic bonds (all of the above)

The peptide bond has all of the following characteristics EXCEPT

freedom to rotate.

All of the following amino acids are optically active EXCEPT

glycine

Which of the following amino acids predominates

glycine

Indicate the type of bond principally responsible for the secondary structure of proteins

hydrogen bonds

The major interaction in which the side chain of serine could participate is

hydrogen bonds

An essential element of the alpha-helical structure of proteins is

hydrogen bonds parallel to the axis

A major force that contributes to the conformation of proteins and in globular proteins, occurs primarily in their interior is

hydrophobic interactions.

Secondary structure of proteins

is maintained by hydrogen bonds

(CH3)2-CH-CH2-CHNH2-COOH:

leucine

The hydrophobic effect is generally thought to be the result of

minimization of the disruption of the normal structure of water by hydrophobic molecules

Cysteine can be converted to cystine by

oxidation

Identify in the following list the chemical bond responsible for forming the primary structure of proteins:

peptide bond

A peptide bond

planar and partial ionic

An amino acid found in large amounts in collagen is

proline

The alpha helix structure of a protein can be considered an example of:

secondary structure

Which of the following amino acids possesses an uncharged side-chain at pH 7.0?

serine

Amino acid side chains which may be involved in hydrogen bonding in proteins include

tyrosine.