Of the 20 standard amino acids only ______ is not optically active . The reason is that it's side chain _____
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69%
Glycine, is the hydrogen
17%
Lysine ,contain only nitrogen
15%
Alanine ,is a simple methyl group
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The Sulphur containing side chain of cysteine is
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26%
Hydrophilic, highly reactive and capable of reacting with another cysteine
59%
Hydrophobic, highly reactive and capable of reacting with another cysteine
6%
Ampiphilic , highly reactive and not capable of reacting with another cysteine
9%
Ampiphilic , highly reactive and capable of reacting with another cysteine
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Which of the following statements about aromatic amino acids is correct?
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58%
On a molar basis, tryptophan absorbs more ultraviolet light than tyrosine.
25%
Histidine's ring structure results in its being categorized as aromatic or basic, depending on pH.
17%
All are strongly hydrophilic
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The peptide alanylglutamylglycylalanylleucine has:
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6%
a disulfide bridge.
59%
four peptide bonds
22%
five peptide bonds
7%
two free amino groups
7%
no free carboxyl group
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Electrophoretic separation at pH 6 of a sample of polypeptide 1 (mw 100) polypeptide 2 (mw 200) and polypeptide 3 (mw 400) would result in which of the following?
(Note: the isoelectric point of each polypeptide occurs at pH 6)
A. Polypeptide 1 would move the farthest
B. Polypeptide 2 would move the farthest
C. Polypeptide 3 would move the farthest
D. None of the polypeptides would move.
(Note: the isoelectric point of each polypeptide occurs at pH 6)
A. Polypeptide 1 would move the farthest
B. Polypeptide 2 would move the farthest
C. Polypeptide 3 would move the farthest
D. None of the polypeptides would move.
A polypeptide with a net positive charge at physiologic pH (~7.4) most likely contains amino acids with R groups of what type?
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18%
Acidic R groups
67%
Basic R groups
4%
Aromatic R groups
10%
Aliphatic R groups
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Three amino acid that are positively charged at neutral ph are
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12%
R, E, H
78%
K, R, H
9%
H , R, C
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During the formation of the peptide bond which of the following takes place?
A. Hydrogen atom is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
B. Hydrogen atom is lost from its carboxyl group of one amino acid and a hydrogen. atom is lost from its amino group of another amino acid
C. Hydroxyl group is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
D. Hydroxyl group is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid
E. None of them
A. Hydrogen atom is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
B. Hydrogen atom is lost from its carboxyl group of one amino acid and a hydrogen. atom is lost from its amino group of another amino acid
C. Hydroxyl group is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
D. Hydroxyl group is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid
E. None of them
In a highly basic solution, pH= 13. the dominant form of glycine is: "
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8%
NH3+-CH2-COO
14%
NH2-CH2-COOH
52%
. NH2-CH2-COO
20%
NH2-CH3 + -COO
6%
NH3+ -CH2-COOH
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The chirality of an amino acid results from the fact that it's alpha carbon:*
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71%
is bonded to four different chemical groups
14%
is in the L absolute configuration in naturally occurring proteins
6%
has no net charge
6%
is a carboxylic acid
3%
is symmetric
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Beneficial for skin, bone and tissue wound healing
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14%
Proline
77%
Leucine
9%
Asparagine
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Three most important glycogenic amino acids
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17%
Tyr ,phe , thr
77%
Gly ,Ala , ser
6%
Ile , val ,pro
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