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FIRST PUBLISH OCTOBER 2024
Intro to Biochemistry (Murphy 301) CH
1 – 4 Questions and Answers
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. - Ans:✔✔-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. - Ans:✔✔-Histidine
All amino acids have a chiral α-carbon EXCEPT ________. - Ans:✔✔-glycine
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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. - Ans:✔✔-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.
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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. - Ans:✔✔-All
statements are correct.
In general, enzymes are what kinds of molecules?
proteins
minerals
carbohydrates
lipids
nucleic acids - Ans:✔✔-proteins
The basic building blocks of proteins are _______ - Ans:✔✔-amino acids
All amino acids are composed what three things attached to it? - Ans:✔✔-central α-carbon that has an
amine group
a carboxylic acid group
and an R group
Page 3/86
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All amino acids except _______ are chiral with the two isomer forms known as the L-isomer and the D-
isomer. - Ans:✔✔-glycine
The ____ is the only isomer known to be incorporated into proteins. - Ans:✔✔-L-isomer
This ionic state, where the carboxylic acid is negative and the amine group is positive, is known as the
__________ state - Ans:✔✔-zwitterionic state
What are the N-terminal and C-terminal residues for the following peptide sequence?
Peptide sequence: EASY - Ans:✔✔-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 - Ans:✔✔-Sun
Which is not a common component of biomolecules?
A. Carbon
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FIRST PUBLISH OCTOBER 2024
Intro to Biochemistry (Murphy 301) CH
1 – 4 Questions and Answers
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. - Ans:✔✔-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. - Ans:✔✔-Histidine
All amino acids have a chiral α-carbon EXCEPT ________. - Ans:✔✔-glycine
Page 1/86
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
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. - Ans:✔✔-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.
Page 2/86
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FIRST PUBLISH OCTOBER 2024
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. - Ans:✔✔-All
statements are correct.
In general, enzymes are what kinds of molecules?
proteins
minerals
carbohydrates
lipids
nucleic acids - Ans:✔✔-proteins
The basic building blocks of proteins are _______ - Ans:✔✔-amino acids
All amino acids are composed what three things attached to it? - Ans:✔✔-central α-carbon that has an
amine group
a carboxylic acid group
and an R group
Page 3/86
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FIRST PUBLISH OCTOBER 2024
All amino acids except _______ are chiral with the two isomer forms known as the L-isomer and the D-
isomer. - Ans:✔✔-glycine
The ____ is the only isomer known to be incorporated into proteins. - Ans:✔✔-L-isomer
This ionic state, where the carboxylic acid is negative and the amine group is positive, is known as the
__________ state - Ans:✔✔-zwitterionic state
What are the N-terminal and C-terminal residues for the following peptide sequence?
Peptide sequence: EASY - Ans:✔✔-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 - Ans:✔✔-Sun
Which is not a common component of biomolecules?
A. Carbon
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