MURPHY 301 Introduction to Biochemistry
Actual Exam Latest Update 2025 Questions
and Correct Answers Rated A+
The side chain of histidine has a typical pKa value in the range of 6.5-7.4.
However, when analyzing the pKa values in a particular protein, scientists
determined that one particular His residue has an unusually low pKa value
of 4.8. Which of the following statements correctly explain this anomaly?
1) The microenvironment around a residue can impact its pKa value.
2) A positively charged amino acid must be in close proximity to this
residue.
3) A negatively charged amino acid must be in close proximity to this
residue.
4) This residue must be located on the surface of the protein. - ANSWER-
Statement 1 and 2
The side chain of ________ has a pKa in the physiological pH range and is
therefore often involved in proton transfer during enzymatic catalysis. -
ANSWER-Histidine
All amino acids have a chiral α-carbon EXCEPT ________. - ANSWER-
glycine
Which of the following statements regarding Anfinsen's denaturing
experiments with ribonuclease A are valid?
,1) Exposing the denatured protein to air oxidation and then dialysis to
remove urea restored the protein to its original functionality.
2) Removing urea by dialysis and then allowing air oxidation of the
denatured protein restored the protein to its original functionality.
3) Denaturing the protein with both urea and β-mercaptoethanol yielded an
inactive protein.
4) Protein folding is determined by its primary sequence. - ANSWER-Only
statements 2, 3, and 4 are valid.
Which of the following statements about protein quaternary structure are
correct?
1) It involves a complex of two or more proteins interacting with each other.
2) The subunits of the structure can be either identical or different.
3) The interactions between subunits can give rise to indefinite growth of
polymeric complexes.
4) Most assemblies of protein subunits have one or more defined axis of
rotation. - ANSWER-All statements are correct.
In general, enzymes are what kinds of molecules?
proteins
minerals
carbohydrates
,lipids
nucleic acids - ANSWER-proteins
The basic building blocks of proteins are _______ - ANSWER-amino acids
All amino acids are composed what three things attached to it? - ANSWER-
central α-carbon that has an amine group
a carboxylic acid group
and an R group
All amino acids except _______ are chiral with the two isomer forms known
as the L-isomer and the D-isomer. - ANSWER-glycine
The ____ is the only isomer known to be incorporated into proteins. -
ANSWER-L-isomer
This ionic state, where the carboxylic acid is negative and the amine group
is positive, is known as the __________ state - ANSWER-zwitterionic state
What are the N-terminal and C-terminal residues for the following peptide
sequence?
Peptide sequence: EASY - ANSWER-E is the N-terminal residue; Y is the
C-terminal residue.
Ultimate source of energy for life on earth is:
A. Sun
B. Geothermal heat
, C. Carbohydrates
D. Fats
E. Other organisms - ANSWER-Sun
Which is not a common component of biomolecules?
A. Carbon
B. Hydrogen
C. Oxygen
D. Nitrogen
E. Chlorine - ANSWER-Chlorine
Which is a basic structural unit of living organisms?
A. Nucleus
B. Cell membrane
C. Tissue
D. Cell
E. Cytoskeleton - ANSWER-Cell
Which of the following is not an organelle?
A. Mitochondria
B. Chloroplast
C. Nucleus
D. Plasma Membrane
E. Golgi Complex - ANSWER-Plasma Membrane
Which of the following is not a role played by carbohydrates in living cells?
A. Energy source
Actual Exam Latest Update 2025 Questions
and Correct Answers Rated A+
The side chain of histidine has a typical pKa value in the range of 6.5-7.4.
However, when analyzing the pKa values in a particular protein, scientists
determined that one particular His residue has an unusually low pKa value
of 4.8. Which of the following statements correctly explain this anomaly?
1) The microenvironment around a residue can impact its pKa value.
2) A positively charged amino acid must be in close proximity to this
residue.
3) A negatively charged amino acid must be in close proximity to this
residue.
4) This residue must be located on the surface of the protein. - ANSWER-
Statement 1 and 2
The side chain of ________ has a pKa in the physiological pH range and is
therefore often involved in proton transfer during enzymatic catalysis. -
ANSWER-Histidine
All amino acids have a chiral α-carbon EXCEPT ________. - ANSWER-
glycine
Which of the following statements regarding Anfinsen's denaturing
experiments with ribonuclease A are valid?
,1) Exposing the denatured protein to air oxidation and then dialysis to
remove urea restored the protein to its original functionality.
2) Removing urea by dialysis and then allowing air oxidation of the
denatured protein restored the protein to its original functionality.
3) Denaturing the protein with both urea and β-mercaptoethanol yielded an
inactive protein.
4) Protein folding is determined by its primary sequence. - ANSWER-Only
statements 2, 3, and 4 are valid.
Which of the following statements about protein quaternary structure are
correct?
1) It involves a complex of two or more proteins interacting with each other.
2) The subunits of the structure can be either identical or different.
3) The interactions between subunits can give rise to indefinite growth of
polymeric complexes.
4) Most assemblies of protein subunits have one or more defined axis of
rotation. - ANSWER-All statements are correct.
In general, enzymes are what kinds of molecules?
proteins
minerals
carbohydrates
,lipids
nucleic acids - ANSWER-proteins
The basic building blocks of proteins are _______ - ANSWER-amino acids
All amino acids are composed what three things attached to it? - ANSWER-
central α-carbon that has an amine group
a carboxylic acid group
and an R group
All amino acids except _______ are chiral with the two isomer forms known
as the L-isomer and the D-isomer. - ANSWER-glycine
The ____ is the only isomer known to be incorporated into proteins. -
ANSWER-L-isomer
This ionic state, where the carboxylic acid is negative and the amine group
is positive, is known as the __________ state - ANSWER-zwitterionic state
What are the N-terminal and C-terminal residues for the following peptide
sequence?
Peptide sequence: EASY - ANSWER-E is the N-terminal residue; Y is the
C-terminal residue.
Ultimate source of energy for life on earth is:
A. Sun
B. Geothermal heat
, C. Carbohydrates
D. Fats
E. Other organisms - ANSWER-Sun
Which is not a common component of biomolecules?
A. Carbon
B. Hydrogen
C. Oxygen
D. Nitrogen
E. Chlorine - ANSWER-Chlorine
Which is a basic structural unit of living organisms?
A. Nucleus
B. Cell membrane
C. Tissue
D. Cell
E. Cytoskeleton - ANSWER-Cell
Which of the following is not an organelle?
A. Mitochondria
B. Chloroplast
C. Nucleus
D. Plasma Membrane
E. Golgi Complex - ANSWER-Plasma Membrane
Which of the following is not a role played by carbohydrates in living cells?
A. Energy source
