MCB Chapter 3
How many essential amino acids are hydrophobic?
6
The protonated amino group of an amino acid will lose a proton when the pH approaches:
9
Naturally occurring proteins contain L amino acids. Which of the following is a possible reason for this phenomenon?
A small excess of L amino acids may have existed in the past.
Which of the following lists puts the amino acids in the CORRECT order of ascending numbers of carbon atoms in the side chain?
Ala < Pro < Phe
Which amino acid would be positively charged at physiological pH?
Arg
Which of the following statements is TRUE of an amino acid?
At pH 11, the amino group is deprotonated.
Asp is to Asn as _____ is to Gln.
Glu
Which of the following peptides can an adult human fully synthesize without relying on any essential amino acids?
Gly-Ser-Tyr-Glu-Gln
The side chain of Q has one more carbon than the side chain of:
N
_____ is an aliphatic amino acid, but it differs from others because its side chain is bonded to both the _____ and the _____ of the backbone.
Proline; nitrogen; α-carbon
The side chain of an amino acid is also known as the:
R group
For an amino acid with a side chain that is a methyl group, as the pH is raised from 1, which of the following statements is TRUE?
The carboxyl group is the first to lose a proton.
The side chain of an amino acid is also known as the:
Their side chains contain four carbon atoms.
Which of the following characteristics is TRUE for both valine and threonine?
They are both neutral at physiological pH (˜pH = 7).
Which of the following lists contain only amino acids with at least one ring structure in the side chain?
Trp; Phe; Tyr
The MOST common characteristic of a child suffering from kwashiorkor is:
a large, protruding belly. - edema
Which of the following is a nonessential amino acid?
alanine
amino acids
alpha carbon, dipolar or zwitterions
A child suffering from kwashiorkor has an inadequate intake of:
amino acids
10) For the peptide, Ala-Arg-Lys-Ala-Asn-Ser-Ala-Ser, what would be the expected charges at pH 1, 7, and 13?
b. +3, +2, -1
Which of the following is a symptom of kwashiorkor?
both lethargy and irritability
Pairs of sulfhydryl groups in close proximity may form _____ bonds.
disulfide
Four of the 20 amino acids begin with the letter "A." Of these, how many are nonessential amino acids?
four
Kwashiorkor is a particular form of malnutrition. The disease was first defined in the 1930s in:
ghana
Which of the following amino acids would contain an overall positive charge at pH 1?
leucine, methionine, glycine and lysine
The pKa of the carboxylic acid group of an amino acid is _____ than the pKa of the amino group.
lower
The only hydrophobic amino acid that does not contain a purely hydrocarbon side chain is _____.
methionine
Which of the following is an essential amino acid?
methionine
Which of the following statements is TRUE of L amino acids but not of D amino acids.
none of the above
An amino acid that can be synthesized by an organism is known as a(n) _____ amino acid.
nonessential
Essential amino acids must be:
obtained from diet
There are three amino acids that begin with the letter "T." Of these, how many are essential amino acids?
two
There are two amino acids that begin with the letter "L." Of these, how many are essential amino acids?
two
Which of the following pairs list the less-reactive amino acid first?
tyrosine, cysteine
