ACS BIOCHEMISTRY EXAM QUESTION WITH COMPLETE SOLUTIONS LATEST 2024.
Henderson-Hasselbach Equation - CORRECT ANSWER - pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis - CORRECT ANSWER - Used in synthesis of a growing
amino acid chain to a polystyrene bead. FMOC is used as a protecting group o...
Henderson-Hasselbach Equation - CORRECT ANSWER - pH = pKa + log ([A-] / [HA])
FMOC Chemical Synthesis - CORRECT 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) - CORRECT ANSWER - Changes soluble protein to solid
precipitate. Protein precipitates when the charges on the protein match the charges in
the solution.
Size-Exclusion Chromatography - CORRECT ANSWER - Separates sample based on
size with smaller molecules eluting later.
Ion-Exchange Chromatography - CORRECT 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 - CORRECT ANSWER - Beads are
coated with a carbon chain. Hydrophobic proteins stick better. Elute with non-H-bonding
solvent (acetonitrile).
Affinity Chromatography - CORRECT ANSWER - Attach a ligand that binds a protein to
a bead. Elute with harsh chemicals or similar ligand.
SDS-PAGE - CORRECT 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 - CORRECT ANSWER - Sodium dodecyl sulfate. Unfolds proteins and gives them
uniform negative charge.
Isoelectric Focusing - CORRECT ANSWER - Variation of gel electrophoresis where
protein charge matters. Involves electrodes and pH gradient. Protein stops at their pI
when neutral.ACS BIOCHEMISTRY EXAM QUESTION WITH COMPLETE SOLUTIONS LATEST 2024 DTT (dithiothreitol) - CORRECT ANSWER - Reduces disulfide bonds.
FDNB (1-fluoro-2,3-dinitrobenzene) - CORRECT 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.
Iodoacetate - CORRECT ANSWER - Adds carboxymethyl group on free -SH groups.
Blocks disulfide bonding.
Homologs - CORRECT ANSWER - Shares 25% identity with another gene
Orthologs - CORRECT ANSWER - Similar genes in different organisms
Paralogs - CORRECT ANSWER - Similar "paired" genes in the same organism
Ramachandran Plot - CORRECT ANSWER - Shows favorable phi-psi angle
combinations. 3 main "wells" for α-helices, ß-sheets, and left-handed α-helices.
Glycine Ramachandran Plot - CORRECT ANSWER - Glycine can adopt more angles.
(H's for R-group).
Proline Ramachandran Plot - CORRECT ANSWER - Proline adopts fewer angles.
Amino group is incorporated into a ring.
α-helices - CORRECT 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 - CORRECT 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 - CORRECT ANSWER - Either parallel or anti-parallel. Often twisted to
increase strength.
Anti-parallel ß-sheet - CORRECT ANSWER - Alternating sheet directions (C & N-
termini don't line-up). Has straight H-bonds.
Parallel ß-sheet - CORRECT ANSWER - Same sheet directions (C & N-termini line up).
Has angled H-bonds.
ß-turns - CORRECT 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.
Loops - CORRECT ANSWER - Not highly structured. Not necessary highly flexible, but
can occasionally move. Very variable in sequence. Disulfide-bonds - CORRECT ANSWER - Bonds between two -SH groups that form
between 2° and 3° structure.
Circular Dichroism - CORRECT ANSWER - Uses UV light to measure 2° structure. Can
be used to measure destabilization.
ß-mercaptoethanol - CORRECT ANSWER - Breaks disulfide bonds.
α-keratin - CORRECT ANSWER - formed from 2 α-helices twisted around each other.
"Coiled coil". Cross-linked by disulfide bonds.
Collagen - CORRECT ANSWER - Repeating sequence of Gly-X-Pro. 3 stranded "coiled
coil". Contains gly core.
Myoglobin 4° Structure - CORRECT ANSWER - Symmetric homodimer,
Hemoglobin 4° Structure - CORRECT ANSWER - Tetramer. Dimer of dimers. α2ß2
tetramer.
α/ß Protein Folding - CORRECT ANSWER - Less distinct areas of α and ß folding.
α+ß Protein Folding - CORRECT ANSWER - Two distinct areas of α and ß folding.
Mechanism of Denaturants - CORRECT ANSWER - Highly soluble, H-binding
molecules. Stabilize protein backbone in water. Allows denatured state to be stabilized.
Temperature Denaturation of Protein - CORRECT ANSWER - Midpoint of reaction is
Tm.
Cooperative Protein Folding - CORRECT ANSWER - Folding transition is sharp. More
reversible.
Folding Funnel - CORRECT ANSWER - Shows 3D version of 2D energy states. Lowest
energy is stable protein. Rough funnel is less cooperative.
Protein-Protein Interfaces - CORRECT ANSWER - "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 - CORRECT ANSWER - Weird interaction where aromatic rings
stack on each other in positive interaction.
σ-hole - CORRECT ANSWER - Methyl group has area of diminished electron density in
center; attracts electronegative groups
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller DoctorReinhad. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £10.63. You're not tied to anything after your purchase.
