ACS BIOCHEMISTRY FINAL|VERIFIED QUESTIONS AND CORRECT DETAILED
ANSWERS|RATED AND GRADED A+ NEW UPDATE| 2026/2027
pKa (chapter 3) - ANSWER✔ measure of the tendency of a group to give up a proton (acidity);
tendency decreases tenfold as pKa increases by one unit
thioester bond (1) - ANSWER✔ compounds with functional group C-S-CoA-C (eg, in acetyl-CoA)
zwitterion (3) - ANSWER✔ dipolar ion with both positive and negative groups but overall neutral
charge; can act as either an acid or base
Isoelectric point (pI) (chapter 3) - ANSWER✔ the characteristic pH at which the net electric charge is
zero
SDS - Sodium Dodecyl Sulfate (chap 3) - ANSWER✔ detergent used to unfold proteins and give them
uniform negative charge
SDS Page (3) - ANSWER✔ chromatography used to separate proteins based on mass. light proteins
travel fast than heavier ones
PCR - Polymerase chain reaction (3) - ANSWER✔ copies DNA multiple times to increase sample size
Isoelectric focusing (chapt 3) - ANSWER✔ procedure used to determine the isoelectric pt (pI) of a
protein. Protein migrates through gel until pH = pI (net charge = 0)
Two-Dimensional Electrophoresis (3) - ANSWER✔ combines isoelectric focusing and SDS
electrophoresis; separates proteins by both molecular weight and pI
specific activity (3) - ANSWER✔ number of enzyme units per mg of total protein (a measure of
enzyme purity)
, activity (3) - ANSWER✔ total units of a certain enzyme in a solution
Peptide bonds (chapter 4) - ANSWER✔ C-N bond with double bond character due to resonance (C-N
bond cannot rotate, and is planar)
Edman degredation (3) - ANSWER✔ used in the sequencing of polypeptides; labels and removes
ONLY the amino-residue from a polypeptide. carried out in a machine called a sequenator
φ in peptide bonding (chapter 4) - ANSWER✔ angle around the α-carbon - amide nitrogen bond
ψ in peptide bonding (chapter 4) - ANSWER✔ angle around the α-carbon - carbonyl carbon bond
Ramachandran Plot (4) - ANSWER✔ shows favoreable φ-ψ angle combinations. 3 main "wells" for α-
helices, β-sheets, and left handed α-helices
Levinthal's Paradox (4) - ANSWER✔ protein folding cannot be a completely random, trial and error
process
chaperonins (4) - ANSWER✔ elaborite protein complexes required for the folding of a number of
cellular proteins that do not fold spontaneously
Henderson-Hasselbach Equation (2) - ANSWER✔ pH = pKa + log([A-]/[HA])
which amino acids are not found in α-helices? (4) - ANSWER✔ glycine and proline. glycine is too
flexible, proline is too rigid to rotate.
which amino acids are commonly found in β turns? (4) - ANSWER✔ glycine, because it is small and
flexible, and proline because it forms cis conformation in tight turns.
β-mercaptoethanol (4) - ANSWER✔ breaks disulfide bonds
ANSWERS|RATED AND GRADED A+ NEW UPDATE| 2026/2027
pKa (chapter 3) - ANSWER✔ measure of the tendency of a group to give up a proton (acidity);
tendency decreases tenfold as pKa increases by one unit
thioester bond (1) - ANSWER✔ compounds with functional group C-S-CoA-C (eg, in acetyl-CoA)
zwitterion (3) - ANSWER✔ dipolar ion with both positive and negative groups but overall neutral
charge; can act as either an acid or base
Isoelectric point (pI) (chapter 3) - ANSWER✔ the characteristic pH at which the net electric charge is
zero
SDS - Sodium Dodecyl Sulfate (chap 3) - ANSWER✔ detergent used to unfold proteins and give them
uniform negative charge
SDS Page (3) - ANSWER✔ chromatography used to separate proteins based on mass. light proteins
travel fast than heavier ones
PCR - Polymerase chain reaction (3) - ANSWER✔ copies DNA multiple times to increase sample size
Isoelectric focusing (chapt 3) - ANSWER✔ procedure used to determine the isoelectric pt (pI) of a
protein. Protein migrates through gel until pH = pI (net charge = 0)
Two-Dimensional Electrophoresis (3) - ANSWER✔ combines isoelectric focusing and SDS
electrophoresis; separates proteins by both molecular weight and pI
specific activity (3) - ANSWER✔ number of enzyme units per mg of total protein (a measure of
enzyme purity)
, activity (3) - ANSWER✔ total units of a certain enzyme in a solution
Peptide bonds (chapter 4) - ANSWER✔ C-N bond with double bond character due to resonance (C-N
bond cannot rotate, and is planar)
Edman degredation (3) - ANSWER✔ used in the sequencing of polypeptides; labels and removes
ONLY the amino-residue from a polypeptide. carried out in a machine called a sequenator
φ in peptide bonding (chapter 4) - ANSWER✔ angle around the α-carbon - amide nitrogen bond
ψ in peptide bonding (chapter 4) - ANSWER✔ angle around the α-carbon - carbonyl carbon bond
Ramachandran Plot (4) - ANSWER✔ shows favoreable φ-ψ angle combinations. 3 main "wells" for α-
helices, β-sheets, and left handed α-helices
Levinthal's Paradox (4) - ANSWER✔ protein folding cannot be a completely random, trial and error
process
chaperonins (4) - ANSWER✔ elaborite protein complexes required for the folding of a number of
cellular proteins that do not fold spontaneously
Henderson-Hasselbach Equation (2) - ANSWER✔ pH = pKa + log([A-]/[HA])
which amino acids are not found in α-helices? (4) - ANSWER✔ glycine and proline. glycine is too
flexible, proline is too rigid to rotate.
which amino acids are commonly found in β turns? (4) - ANSWER✔ glycine, because it is small and
flexible, and proline because it forms cis conformation in tight turns.
β-mercaptoethanol (4) - ANSWER✔ breaks disulfide bonds
