BASI PILATES ACTUAL
EXAM PAPER 2026
QUESTIONS WITH
ANSWERS GRADED A+
Henderson-Hasselbach Equation - ANSWERS--pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis - ANSWERS--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) - ANSWERS--Changes soluble protein to solid precipitate.
Protein precipitates when the charges on the protein match the charges in the
solution.
Size-Exclusion Chromatography - ANSWERS--Separates sample based on size with
smaller molecules eluting later.
Ion-Exchange Chromatography - ANSWERS--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 - ANSWERS--Beads are coated with
a carbon chain. Hydrophobic proteins stick better. Elute with non-H-bonding solvent
(acetonitrile).
,Affinity Chromatography - ANSWERS--Attach a ligand that binds a protein to a bead.
Elute with harsh chemicals or similar ligand.
SDS-PAGE - ANSWERS--Uses SDS. Gel is made from cross-linked polyacrylamide.
Separates based off of mass with smaller molecules moving faster. Visualized with
Coomassie blue.
SDS - ANSWERS--Sodium dodecyl sulfate. Unfolds proteins and gives them uniform
negative charge.
Isoelectric Focusing - ANSWERS--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) - ANSWERS--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) - ANSWERS--Reduces disulfide bonds.
Iodoacetate - ANSWERS--Adds carboxymethyl group on free -SH groups. Blocks
disulfide bonding.
Homologs - ANSWERS--Shares 25% identity with another gene
Orthologs - ANSWERS--Similar genes in different organisms
Paralogs - ANSWERS--Similar "paired" genes in the same organism
Ramachandran Plot - ANSWERS--Shows favorable phi-psi angle combinations. 3
main "wells" for α-helices, ß-sheets, and left-handed α-helices.
Glycine Ramachandran Plot - ANSWERS--Glycine can adopt more angles. (H's for
R-group).
Proline Ramachandran Plot - ANSWERS--Proline adopts fewer angles. Amino group
is incorporated into a ring.
α-helices - ANSWERS--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 - ANSWERS--Formed from added dipole moments of all hydrogen
bonds in an α-helix. N-terminus is δ+ and C-terminus is δ-.
ß-sheet - ANSWERS--Either parallel or anti-parallel. Often twisted to increase
strength.
Anti-parallel ß-sheet - ANSWERS--Alternating sheet directions (C & N-termini don't
line-up). Has straight H-bonds.
, Parallel ß-sheet - ANSWERS--Same sheet directions (C & N-termini line up). Has
angled H-bonds.
ß-turns - ANSWERS--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.
Loops - ANSWERS--Not highly structured. Not necessary highly flexible, but can
occasionally move. Very variable in sequence.
Circular Dichroism - ANSWERS--Uses UV light to measure 2° structure. Can be
used to measure destabilization.
Disulfide-bonds - ANSWERS--Bonds between two -SH groups that form between 2°
and 3° structure.
ß-mercaptoethanol - ANSWERS--Breaks disulfide bonds.
α-keratin - ANSWERS--formed from 2 α-helices twisted around each other. "Coiled
coil". Cross-linked by disulfide bonds.
Collagen - ANSWERS--Repeating sequence of Gly-X-Pro. 3 stranded "coiled coil".
Contains gly core.
Myoglobin 4° Structure - ANSWERS--Symmetric homodimer,
Hemoglobin 4° Structure - ANSWERS--Tetramer. Dimer of dimers. α2ß2 tetramer.
α/ß Protein Folding - ANSWERS--Less distinct areas of α and ß folding.
α+ß Protein Folding - ANSWERS--Two distinct areas of α and ß folding.
Mechanism of Denaturants - ANSWERS--Highly soluble, H-binding molecules.
Stabilize protein backbone in water. Allows denatured state to be stabilized.
Temperature Denaturation of Protein - ANSWERS--Midpoint of reaction is Tm.
Cooperative Protein Folding - ANSWERS--Folding transition is sharp. More
reversible.
Folding Funnel - ANSWERS--Shows 3D version of 2D energy states. Lowest energy
is stable protein. Rough funnel is less cooperative.
Protein-Protein Interfaces - ANSWERS--"Core" and "fringe" of the interfaces. Core is
more hydrophobic and is on the inside when interfaced. Fringe is more hydrophilic.
π-π Ring Stacking - ANSWERS--Weird interaction where aromatic rings stack on
each other in positive interaction.
EXAM PAPER 2026
QUESTIONS WITH
ANSWERS GRADED A+
Henderson-Hasselbach Equation - ANSWERS--pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis - ANSWERS--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) - ANSWERS--Changes soluble protein to solid precipitate.
Protein precipitates when the charges on the protein match the charges in the
solution.
Size-Exclusion Chromatography - ANSWERS--Separates sample based on size with
smaller molecules eluting later.
Ion-Exchange Chromatography - ANSWERS--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 - ANSWERS--Beads are coated with
a carbon chain. Hydrophobic proteins stick better. Elute with non-H-bonding solvent
(acetonitrile).
,Affinity Chromatography - ANSWERS--Attach a ligand that binds a protein to a bead.
Elute with harsh chemicals or similar ligand.
SDS-PAGE - ANSWERS--Uses SDS. Gel is made from cross-linked polyacrylamide.
Separates based off of mass with smaller molecules moving faster. Visualized with
Coomassie blue.
SDS - ANSWERS--Sodium dodecyl sulfate. Unfolds proteins and gives them uniform
negative charge.
Isoelectric Focusing - ANSWERS--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) - ANSWERS--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) - ANSWERS--Reduces disulfide bonds.
Iodoacetate - ANSWERS--Adds carboxymethyl group on free -SH groups. Blocks
disulfide bonding.
Homologs - ANSWERS--Shares 25% identity with another gene
Orthologs - ANSWERS--Similar genes in different organisms
Paralogs - ANSWERS--Similar "paired" genes in the same organism
Ramachandran Plot - ANSWERS--Shows favorable phi-psi angle combinations. 3
main "wells" for α-helices, ß-sheets, and left-handed α-helices.
Glycine Ramachandran Plot - ANSWERS--Glycine can adopt more angles. (H's for
R-group).
Proline Ramachandran Plot - ANSWERS--Proline adopts fewer angles. Amino group
is incorporated into a ring.
α-helices - ANSWERS--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 - ANSWERS--Formed from added dipole moments of all hydrogen
bonds in an α-helix. N-terminus is δ+ and C-terminus is δ-.
ß-sheet - ANSWERS--Either parallel or anti-parallel. Often twisted to increase
strength.
Anti-parallel ß-sheet - ANSWERS--Alternating sheet directions (C & N-termini don't
line-up). Has straight H-bonds.
, Parallel ß-sheet - ANSWERS--Same sheet directions (C & N-termini line up). Has
angled H-bonds.
ß-turns - ANSWERS--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.
Loops - ANSWERS--Not highly structured. Not necessary highly flexible, but can
occasionally move. Very variable in sequence.
Circular Dichroism - ANSWERS--Uses UV light to measure 2° structure. Can be
used to measure destabilization.
Disulfide-bonds - ANSWERS--Bonds between two -SH groups that form between 2°
and 3° structure.
ß-mercaptoethanol - ANSWERS--Breaks disulfide bonds.
α-keratin - ANSWERS--formed from 2 α-helices twisted around each other. "Coiled
coil". Cross-linked by disulfide bonds.
Collagen - ANSWERS--Repeating sequence of Gly-X-Pro. 3 stranded "coiled coil".
Contains gly core.
Myoglobin 4° Structure - ANSWERS--Symmetric homodimer,
Hemoglobin 4° Structure - ANSWERS--Tetramer. Dimer of dimers. α2ß2 tetramer.
α/ß Protein Folding - ANSWERS--Less distinct areas of α and ß folding.
α+ß Protein Folding - ANSWERS--Two distinct areas of α and ß folding.
Mechanism of Denaturants - ANSWERS--Highly soluble, H-binding molecules.
Stabilize protein backbone in water. Allows denatured state to be stabilized.
Temperature Denaturation of Protein - ANSWERS--Midpoint of reaction is Tm.
Cooperative Protein Folding - ANSWERS--Folding transition is sharp. More
reversible.
Folding Funnel - ANSWERS--Shows 3D version of 2D energy states. Lowest energy
is stable protein. Rough funnel is less cooperative.
Protein-Protein Interfaces - ANSWERS--"Core" and "fringe" of the interfaces. Core is
more hydrophobic and is on the inside when interfaced. Fringe is more hydrophilic.
π-π Ring Stacking - ANSWERS--Weird interaction where aromatic rings stack on
each other in positive interaction.
