Page 1 of 31
ACS BIOCHEMISTRY EXAM TEST EXAM||
QUESTIONS AND 100% CORRECT ANSWERS
WITH A GUARANTEED A+|| LATEST AND
COMPLETE UPDATE 2025 WITH VERIFIED
SOLUTIONS|| ASSURED PASS!!!
Henderson-Hasselbach Equation - ANSWER- pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis - ANSWER- Used in synthesis of a growing amino
acid chain to a polystyrene bead. FMOC is used as a protecting group on the N-
terminus.
Salting Out (Purification) - ANSWER- Changes soluble protein to solid
precipitate. Protein precipitates when the charges on the protein match the charges
in the solution.
Size-Exclusion Chromatography - ANSWER- Separates sample based on size with
smaller molecules eluting later.
Ion-Exchange Chromatography - ANSWER- Separates sample based on charge.
CM attracts +, DEAE attracts -. May have repulsion effect on like charges. Salt or
acid used to remove stuck proteins.
Hydrophobic/Reverse Phase Chromatography - ANSWER- Beads are coated with
a carbon chain. Hydrophobic proteins stick better. Elute with non-H-bonding
solvent (acetonitrile).
Affinity Chromatography - ANSWER- Attach a ligand that binds a protein to a
bead. Elute with harsh chemicals or similar ligand.
,Page 2 of 31
SDS-PAGE - ANSWER- Uses SDS. Gel is made from cross-linked
polyacrylamide. Separates based off of mass with smaller molecules moving faster.
Visualized with Coomassie blue.
SDS - ANSWER- Sodium dodecyl sulfate. Unfolds proteins and gives them
uniform negative charge.
Isoelectric Focusing - ANSWER- Variation of gel electrophoresis where protein
charge matters. Involves electrodes and pH gradient. Protein stops at their pI when
neutral.
FDNB (1-fluoro-2,3-dinitrobenzene) - ANSWER- FDNB reacts with the N-
terminus of the protein to produce a 2,4-dinitrophenol derivative that labels the
first residue. Can repeat hydrolysis to determine sequential amino acids.
DTT (dithiothreitol) - ANSWER- Reduces disulfide bonds.
Iodoacetate - ANSWER- Adds carboxymethyl group on free -SH groups. Blocks
disulfide bonding.
Homologs - ANSWER- Shares 25% identity with another gene
Orthologs - ANSWER- Similar genes in different organisms
Paralogs - ANSWER- Similar "paired" genes in the same organism
,Page 3 of 31
Ramachandran Plot - ANSWER- Shows favorable phi-psi angle combinations. 3
main "wells" for α-helices, ß-sheets, and left-handed α-helices.
Glycine Ramachandran Plot - ANSWER- Glycine can adopt more angles. (H's for
R-group).
Proline Ramachandran Plot - ANSWER- Proline adopts fewer angles. Amino
group is incorporated into a ring.
α-helices - ANSWER- Ala is common, Gly & Pro are not very common. Side-
chain interactions every 3 or 4 residues. Turns once every 3.6 residues. Distance
between backbones is 5.4Å.
Helix Dipole - ANSWER- Formed from added dipole moments of all hydrogen
bonds in an α-helix. N-terminus is δ+ and C-terminus is δ-.
ß-sheet - ANSWER- Either parallel or anti-parallel. Often twisted to increase
strength.
Anti-parallel ß-sheet - ANSWER- Alternating sheet directions (C & N-termini
don't line-up). Has straight H-bonds.
Parallel ß-sheet - ANSWER- Same sheet directions (C & N-termini line up). Has
angled H-bonds.
ß-turns - ANSWER- Tight u-turns with specific phi-psi angles. Must have gly at
position 3. Proline may also be at ß-turn because it can have a cis-omega angle.
, Page 4 of 31
Loops - ANSWER- Not highly structured. Not necessary highly flexible, but can
occasionally move. Very variable in sequence.
Circular Dichroism - ANSWER- Uses UV light to measure 2° structure. Can be
used to measure destabilization.
Disulfide-bonds - ANSWER- Bonds between two -SH groups that form between
2° and 3° structure.
ß-mercaptoethanol - ANSWER- Breaks disulfide bonds.
α-keratin - ANSWER- formed from 2 α-helices twisted around each other. "Coiled
coil". Cross-linked by disulfide bonds.
Collagen - ANSWER- Repeating sequence of Gly-X-Pro. 3 stranded "coiled coil".
Contains gly core.
Myoglobin 4° Structure - ANSWER- Symmetric homodimer,
Hemoglobin 4° Structure - ANSWER- Tetramer. Dimer of dimers. α2ß2 tetramer.
α/ß Protein Folding - ANSWER- Less distinct areas of α and ß folding.
α+ß Protein Folding - ANSWER- Two distinct areas of α and ß folding.
Mechanism of Denaturants - ANSWER- Highly soluble, H-binding molecules.
Stabilize protein backbone in water. Allows denatured state to be stabilized.
ACS BIOCHEMISTRY EXAM TEST EXAM||
QUESTIONS AND 100% CORRECT ANSWERS
WITH A GUARANTEED A+|| LATEST AND
COMPLETE UPDATE 2025 WITH VERIFIED
SOLUTIONS|| ASSURED PASS!!!
Henderson-Hasselbach Equation - ANSWER- pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis - ANSWER- Used in synthesis of a growing amino
acid chain to a polystyrene bead. FMOC is used as a protecting group on the N-
terminus.
Salting Out (Purification) - ANSWER- Changes soluble protein to solid
precipitate. Protein precipitates when the charges on the protein match the charges
in the solution.
Size-Exclusion Chromatography - ANSWER- Separates sample based on size with
smaller molecules eluting later.
Ion-Exchange Chromatography - ANSWER- Separates sample based on charge.
CM attracts +, DEAE attracts -. May have repulsion effect on like charges. Salt or
acid used to remove stuck proteins.
Hydrophobic/Reverse Phase Chromatography - ANSWER- Beads are coated with
a carbon chain. Hydrophobic proteins stick better. Elute with non-H-bonding
solvent (acetonitrile).
Affinity Chromatography - ANSWER- Attach a ligand that binds a protein to a
bead. Elute with harsh chemicals or similar ligand.
,Page 2 of 31
SDS-PAGE - ANSWER- Uses SDS. Gel is made from cross-linked
polyacrylamide. Separates based off of mass with smaller molecules moving faster.
Visualized with Coomassie blue.
SDS - ANSWER- Sodium dodecyl sulfate. Unfolds proteins and gives them
uniform negative charge.
Isoelectric Focusing - ANSWER- Variation of gel electrophoresis where protein
charge matters. Involves electrodes and pH gradient. Protein stops at their pI when
neutral.
FDNB (1-fluoro-2,3-dinitrobenzene) - ANSWER- FDNB reacts with the N-
terminus of the protein to produce a 2,4-dinitrophenol derivative that labels the
first residue. Can repeat hydrolysis to determine sequential amino acids.
DTT (dithiothreitol) - ANSWER- Reduces disulfide bonds.
Iodoacetate - ANSWER- Adds carboxymethyl group on free -SH groups. Blocks
disulfide bonding.
Homologs - ANSWER- Shares 25% identity with another gene
Orthologs - ANSWER- Similar genes in different organisms
Paralogs - ANSWER- Similar "paired" genes in the same organism
,Page 3 of 31
Ramachandran Plot - ANSWER- Shows favorable phi-psi angle combinations. 3
main "wells" for α-helices, ß-sheets, and left-handed α-helices.
Glycine Ramachandran Plot - ANSWER- Glycine can adopt more angles. (H's for
R-group).
Proline Ramachandran Plot - ANSWER- Proline adopts fewer angles. Amino
group is incorporated into a ring.
α-helices - ANSWER- Ala is common, Gly & Pro are not very common. Side-
chain interactions every 3 or 4 residues. Turns once every 3.6 residues. Distance
between backbones is 5.4Å.
Helix Dipole - ANSWER- Formed from added dipole moments of all hydrogen
bonds in an α-helix. N-terminus is δ+ and C-terminus is δ-.
ß-sheet - ANSWER- Either parallel or anti-parallel. Often twisted to increase
strength.
Anti-parallel ß-sheet - ANSWER- Alternating sheet directions (C & N-termini
don't line-up). Has straight H-bonds.
Parallel ß-sheet - ANSWER- Same sheet directions (C & N-termini line up). Has
angled H-bonds.
ß-turns - ANSWER- Tight u-turns with specific phi-psi angles. Must have gly at
position 3. Proline may also be at ß-turn because it can have a cis-omega angle.
, Page 4 of 31
Loops - ANSWER- Not highly structured. Not necessary highly flexible, but can
occasionally move. Very variable in sequence.
Circular Dichroism - ANSWER- Uses UV light to measure 2° structure. Can be
used to measure destabilization.
Disulfide-bonds - ANSWER- Bonds between two -SH groups that form between
2° and 3° structure.
ß-mercaptoethanol - ANSWER- Breaks disulfide bonds.
α-keratin - ANSWER- formed from 2 α-helices twisted around each other. "Coiled
coil". Cross-linked by disulfide bonds.
Collagen - ANSWER- Repeating sequence of Gly-X-Pro. 3 stranded "coiled coil".
Contains gly core.
Myoglobin 4° Structure - ANSWER- Symmetric homodimer,
Hemoglobin 4° Structure - ANSWER- Tetramer. Dimer of dimers. α2ß2 tetramer.
α/ß Protein Folding - ANSWER- Less distinct areas of α and ß folding.
α+ß Protein Folding - ANSWER- Two distinct areas of α and ß folding.
Mechanism of Denaturants - ANSWER- Highly soluble, H-binding molecules.
Stabilize protein backbone in water. Allows denatured state to be stabilized.
