Acs Biochemistry Exam With Correct
Answers (A+Graded)
Henderson-Hasselbach Equation
pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis
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)
Changes soluble protein to solid precipitate. Protein precipitates when the charges on the protein match
the charges in the solution.
Size-Exclusion Chromatography
Separates sample based on size with smaller molecules eluting later.
Ion-Exchange Chromatography
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
,Beads are coated with a carbon chain. Hydrophobic proteins stick better. Elute with non-H-bonding
solvent (acetonitrile).
Affinity Chromatography
Attach a ligand that binds a protein to a bead. Elute with harsh chemicals or similar ligand.
SDS-PAGE
Uses SDS. Gel is made from cross-linked polyacrylamide. Separates based off of mass with smaller
molecules moving faster. Visualized with Coomassie blue.
SDS
Sodium dodecyl sulfate. Unfolds proteins and gives them uniform negative charge.
Isoelectric Focusing
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)
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)
Reduces disulfide bonds.
Iodoacetate
Adds carboxymethyl group on free -SH groups. Blocks disulfide bonding.
Homologs
Shares 25% identity with another gene
Orthologs
Similar genes in different organisms
Paralogs
Similar "paired" genes in the same organism
Ramachandran Plot
Shows favorable phi-psi angle combinations. 3 main "wells" for α-helices, ß-sheets, and left-handed α-
helices.
Glycine Ramachandran Plot
Answers (A+Graded)
Henderson-Hasselbach Equation
pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis
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)
Changes soluble protein to solid precipitate. Protein precipitates when the charges on the protein match
the charges in the solution.
Size-Exclusion Chromatography
Separates sample based on size with smaller molecules eluting later.
Ion-Exchange Chromatography
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
,Beads are coated with a carbon chain. Hydrophobic proteins stick better. Elute with non-H-bonding
solvent (acetonitrile).
Affinity Chromatography
Attach a ligand that binds a protein to a bead. Elute with harsh chemicals or similar ligand.
SDS-PAGE
Uses SDS. Gel is made from cross-linked polyacrylamide. Separates based off of mass with smaller
molecules moving faster. Visualized with Coomassie blue.
SDS
Sodium dodecyl sulfate. Unfolds proteins and gives them uniform negative charge.
Isoelectric Focusing
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)
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)
Reduces disulfide bonds.
Iodoacetate
Adds carboxymethyl group on free -SH groups. Blocks disulfide bonding.
Homologs
Shares 25% identity with another gene
Orthologs
Similar genes in different organisms
Paralogs
Similar "paired" genes in the same organism
Ramachandran Plot
Shows favorable phi-psi angle combinations. 3 main "wells" for α-helices, ß-sheets, and left-handed α-
helices.
Glycine Ramachandran Plot
