BIOCHEMISTRY CONCEPTS AND
CONNECTIONS 2026 MOLECULAR
STRUCTURE AND FUNCTION TEST PAPER
QUESTIONS AND SOLUTIONS GRADED A+
◉ Protein biosynthesis uses only ________
.L-amino acids
R-amino acids
D-amino acids
S-amino acids
L-amino acids. Answer: L-amino acids
◉ All amino acids have a chiral α-carbon EXCEPT ________.
Tryptophan
Proline
Alanine
Glycine. Answer: Glycine
,A key feature of amino acids is that the α carbon is chiral. When a
carbon atom is bound to four unique groups, it creates a chiral
center (also known as a stereocenter).
◉ The side chain of ________ has a pKa in the physiological pH range
and is therefore often involved in proton transfer during enzymatic
catalysis
.Arg
His
Glu
Asp
His. Answer: His (histidine)
Histidine is an α-amino acid involved in the biosynthesis of proteins.
The structure of histidine includes an α-amino acid, a carboxylic acid
group, and an imidazole side chain. Histidine was initially thought to
be essential only for infants; however, it has since been found to be
essential for adults too.
◉ At physiological pH, the carboxylic acid group of an amino acid
will be ________, while the amino group will be ________, yielding the
zwitterion form.
deprotonated, protonated
protonated, protonated
, deprotonated, deprotonated
protonated, deprotonated. Answer: deprotonated, protonated
◉ Which of the following modified amino acids is incorporated
during translation rather than being modified post-translationally?
Selenocysteine
N-ε-acetyllysine
γ-carboxyglutamate
Phosphoserine. Answer: Selenocysteine
◉ Proteins have what charge on their carboxyl terminals at
physiological pH?Positive
Zero
Negative
Not enough information to determine. Answer: Negative
◉ If the R group of an amino acid is -CH3, then the name of this
compound is ________.
Alanine
Isoleucine
3-methyl amino acid
CONNECTIONS 2026 MOLECULAR
STRUCTURE AND FUNCTION TEST PAPER
QUESTIONS AND SOLUTIONS GRADED A+
◉ Protein biosynthesis uses only ________
.L-amino acids
R-amino acids
D-amino acids
S-amino acids
L-amino acids. Answer: L-amino acids
◉ All amino acids have a chiral α-carbon EXCEPT ________.
Tryptophan
Proline
Alanine
Glycine. Answer: Glycine
,A key feature of amino acids is that the α carbon is chiral. When a
carbon atom is bound to four unique groups, it creates a chiral
center (also known as a stereocenter).
◉ The side chain of ________ has a pKa in the physiological pH range
and is therefore often involved in proton transfer during enzymatic
catalysis
.Arg
His
Glu
Asp
His. Answer: His (histidine)
Histidine is an α-amino acid involved in the biosynthesis of proteins.
The structure of histidine includes an α-amino acid, a carboxylic acid
group, and an imidazole side chain. Histidine was initially thought to
be essential only for infants; however, it has since been found to be
essential for adults too.
◉ At physiological pH, the carboxylic acid group of an amino acid
will be ________, while the amino group will be ________, yielding the
zwitterion form.
deprotonated, protonated
protonated, protonated
, deprotonated, deprotonated
protonated, deprotonated. Answer: deprotonated, protonated
◉ Which of the following modified amino acids is incorporated
during translation rather than being modified post-translationally?
Selenocysteine
N-ε-acetyllysine
γ-carboxyglutamate
Phosphoserine. Answer: Selenocysteine
◉ Proteins have what charge on their carboxyl terminals at
physiological pH?Positive
Zero
Negative
Not enough information to determine. Answer: Negative
◉ If the R group of an amino acid is -CH3, then the name of this
compound is ________.
Alanine
Isoleucine
3-methyl amino acid
