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ACS BIOCHEMISTRY EXAM 2024 Questions and Verified Answers, 100% Guarantee Pass
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ACS BIOCHEMISTRY EXAM-.pdf file:///C:/Users/HP/Desktop/New%20folder/ACS%20BIOCHEMISACS BIOCHEMISTRY EXAM
1. Henderson-Hasselbach Equation
Answer pH = pKa + log ([A-] / [HA])
2. FMOC Chemical Synthesis
Answer Used in synthesis of a growing amino acid chain toa polystyrene bead. FMOC is used as
a protecting group on the N-terminus.
3. Salting Out (Purification)
Answer Changes soluble protein to solid precipitate. Proteinprecipitates when the charges on
the protein match the charges in the solution.
4. Size-Exclusion Chromatography
Answer Separates sample based on size with smallermolecules eluting later.
5. Ion-Exchange Chromatography
Answer Separates sample based on charge. CM at-tracts +, DEAE attracts -. May have
repulsion effect on like charges. Salt or acid used to remove stuck proteins.
6. Hydrophobic/Reverse Phase Chromatography
Answer Beads are coated with a car-bon chain. Hydrophobic proteins stick better. Elute with
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non-H-bonding solvent (acetonitrile).
7. Affinity Chromatography
Answer Attach a ligand that binds a protein to a bead. Elutewith harsh chemicals or similar
ligand.
8. SDS-PAGE
Answer Uses SDS. Gel is made from cross-linked polyacrylamide. Separatesbased off of mass with
smaller molecules moving faster.Visualized with Coomassieblue.
9. SDS
Answer Sodium dodecyl sulfate. Unfolds proteins and gives them uniform negativecharge.
10. Isoelectric Focusing
Answer Variation of gel electrophoresis where protein charge matters. Involves electrodes and
pH gradient. Protein stops at their pI when neutral.
11. FDNB (1-fluoro-2,3-dinitrobenzene)
Answer FDNB reacts with the N-terminus of theprotein to produce a 2,4-dinitrophenol
derivative that labels the first residue. Can repeat hydrolysis to determine sequential amino
acids.
12. DTT (dithiothreitol)
Answer Reduces disulfide bonds.
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13. Iodoacetate
Answer Adds carboxymethyl group on free -SH groups. Blocks disulfidebonding.
14. Homologs
Answer Shares 25% identity with another gene
15. Orthologs
Answer Similar genes in different organisms
16. Paralogs
Answer Similar "paired" genes in the same organism
17. Ramachandran Plot
Answer Shows favorable phi-psi angle combinations. 3 main"wells" for ±h-elices, ß-sheets,
and left-handed ±h-elices.
18. Glycine Ramachandran Plot
Answer Glycine can adopt more angles. (H's forR-group).
19. Proline Ramachandran Plot
Answer Proline adopts fewer angles. Amino group isincorporated into a ring.
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20. ±h-elices
Answer Ala is common, Gly & Pro are not very common. Side-chain inter- actions every 3
or 4 residues. Turns once every 3.6 residues. Distance betweenbackbones is 5.4Å.
21. Helix Dipole
Answer Formed from added dipole moments of all hydrogen bonds in an
±h-elix. N-terminus is ´+and C-terminus is ´-.
22. ß-sheet
Answer Either parallel or anti-parallel. Often twisted to increase strength.
23. Anti-parallel ß-sheet
Answer Alternating sheet directions (C & N-termini don't line-up).Has straight H-bonds.
24. Parallel ß-sheet
Answer Same sheet directions (C & N-termini line up). Has angledH-bonds.
25. 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.
26. Loops
Answer Not highly structured. Not necessary highly flexible, but can occasionallymove. Very
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