MURPHY 301 EXAM
MURPHY 301 EXAM INTRODUCTION TO BIOCHEMISTRY
QUESTIONS AND CORRECT ANSWERS GRADED 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. -Correct 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. -Correct Answer ✔Histidine
All amino acids have a chiral α-carbon EXCEPT ________. -Correct 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.
MURPHY 301 EXAM
,MURPHY 301 EXAM
3) Denaturing the protein with both urea and β-mercaptoethanol yielded an inactive
protein.
4) Protein folding is determined by its primary sequence. -Correct 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. -
Correct Answer ✔All statements are correct.
In general, enzymes are what kinds of molecules?
proteins
minerals
carbohydrates
lipids
nucleic acids -Correct Answer ✔proteins
The basic building blocks of proteins are _______ -Correct Answer ✔amino acids
All amino acids are composed what three things attached to it? -Correct Answer
✔central α-carbon that has an amine group
MURPHY 301 EXAM
,MURPHY 301 EXAM
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. -Correct Answer ✔glycine
The ____ is the only isomer known to be incorporated into proteins. -Correct Answer
✔L-isomer
This ionic state, where the carboxylic acid is negative and the amine group is positive, is
known as the __________ state -Correct Answer ✔zwitterionic state
What are the N-terminal and C-terminal residues for the following peptide sequence?
Peptide sequence: EASY -Correct 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 -Correct Answer ✔Sun
Which is not a common component of biomolecules?
A. Carbon
B. Hydrogen
C. Oxygen
MURPHY 301 EXAM
, MURPHY 301 EXAM
D. Nitrogen
E. Chlorine -Correct Answer ✔Chlorine
Which is a basic structural unit of living organisms?
A. Nucleus
B. Cell membrane
C. Tissue
D. Cell
E. Cytoskeleton -Correct Answer ✔Cell
Which of the following is not an organelle?
A. Mitochondria
B. Chloroplast
C. Nucleus
D. Plasma Membrane
E. Golgi Complex -Correct Answer ✔Plasma Membrane
Which of the following is not a role played by carbohydrates in living cells?
A. Energy source
B. Structural support
C. Intercellular communication
D. Both A and B
E. All roles are played -Correct Answer ✔All roles are played by carbohydrates in living
cells
Metabolism is best defined as the...
MURPHY 301 EXAM
MURPHY 301 EXAM INTRODUCTION TO BIOCHEMISTRY
QUESTIONS AND CORRECT ANSWERS GRADED 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. -Correct 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. -Correct Answer ✔Histidine
All amino acids have a chiral α-carbon EXCEPT ________. -Correct 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.
MURPHY 301 EXAM
,MURPHY 301 EXAM
3) Denaturing the protein with both urea and β-mercaptoethanol yielded an inactive
protein.
4) Protein folding is determined by its primary sequence. -Correct 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. -
Correct Answer ✔All statements are correct.
In general, enzymes are what kinds of molecules?
proteins
minerals
carbohydrates
lipids
nucleic acids -Correct Answer ✔proteins
The basic building blocks of proteins are _______ -Correct Answer ✔amino acids
All amino acids are composed what three things attached to it? -Correct Answer
✔central α-carbon that has an amine group
MURPHY 301 EXAM
,MURPHY 301 EXAM
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. -Correct Answer ✔glycine
The ____ is the only isomer known to be incorporated into proteins. -Correct Answer
✔L-isomer
This ionic state, where the carboxylic acid is negative and the amine group is positive, is
known as the __________ state -Correct Answer ✔zwitterionic state
What are the N-terminal and C-terminal residues for the following peptide sequence?
Peptide sequence: EASY -Correct 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 -Correct Answer ✔Sun
Which is not a common component of biomolecules?
A. Carbon
B. Hydrogen
C. Oxygen
MURPHY 301 EXAM
, MURPHY 301 EXAM
D. Nitrogen
E. Chlorine -Correct Answer ✔Chlorine
Which is a basic structural unit of living organisms?
A. Nucleus
B. Cell membrane
C. Tissue
D. Cell
E. Cytoskeleton -Correct Answer ✔Cell
Which of the following is not an organelle?
A. Mitochondria
B. Chloroplast
C. Nucleus
D. Plasma Membrane
E. Golgi Complex -Correct Answer ✔Plasma Membrane
Which of the following is not a role played by carbohydrates in living cells?
A. Energy source
B. Structural support
C. Intercellular communication
D. Both A and B
E. All roles are played -Correct Answer ✔All roles are played by carbohydrates in living
cells
Metabolism is best defined as the...
MURPHY 301 EXAM
