ACS BIOCHEMISTRY CERTIFICATION SCRIPT 2026 QUESTIONS WITH SOLUTIONS GRADED A+, Exams of Biochemistry

ACS BIOCHEMISTRY CERTIFICATION SCRIPT 2026 QUESTIONS WITH SOLUTIONS GRADED A+

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2025/2026

Available from 03/11/2026

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ACS BIOCHEMISTRY CERTIFICATIONACS BIOCHEMISTRY CERTIFICATION
SCRIPT 2026 QUESTIONS WITHSCRIPT 2026 QUESTIONS WITH
SOLUTIONS GRADED A+SOLUTIONS GRADED A+
Henderson-Hasselbach Equation.
Answer: pH = pKa + log ([A-] / [HA])
pI (isoelectric point).
Answer: pH at which the protein has no net charge.
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.
pH.
Answer: Measure of the acidity or basicity of a solution.
pKa.
Answer: The pH at which half of a given species is deprotonated.
Net charge of proteins.
Answer: Depends on solution pH relative to pKa values.
Salting Out (Purification).
Answer: Changes soluble protein to solid precipitate. Protein precipitates
when the charges on the protein match the charges in the solution.
Primary structure.
Answer: Amino acid sequence of a protein.
Secondary structure.
Answer: Alpha helices and beta sheets in proteins.
Tertiary structure.
Answer: 3D folding of a protein, involving hydrophobic core, H-bonds, and
salt bridges.
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14
pf15
pf16
pf17
pf18
pf19
pf1a
pf1b
pf1c
pf1d
pf1e
pf1f
pf20
pf21
pf22
pf23
pf24
pf25
pf26
pf27
pf28
pf29

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ACS BIOCHEMISTRY CERTIFICATIONACS BIOCHEMISTRY CERTIFICATION

SCRIPT 2026 QUESTIONS WITHSCRIPT 2026 QUESTIONS WITH

SOLUTIONS GRADED A+SOLUTIONS GRADED A+

  • Henderson-Hasselbach Equation. Answer: pH = pKa + log ([A-] / [HA])
  • pI (isoelectric point). Answer: pH at which the protein has no net charge.
  • 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.
  • pH. Answer: Measure of the acidity or basicity of a solution.
  • pKa. Answer: The pH at which half of a given species is deprotonated.
  • Net charge of proteins. Answer: Depends on solution pH relative to pKa values.
  • Salting Out (Purification). Answer: Changes soluble protein to solid precipitate. Protein precipitates when the charges on the protein match the charges in the solution.
  • Primary structure. Answer: Amino acid sequence of a protein.
  • Secondary structure. Answer: Alpha helices and beta sheets in proteins.
  • Tertiary structure. Answer: 3D folding of a protein, involving hydrophobic core, H-bonds, and salt bridges.
  • 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.
  • Quaternary structure. Answer: Assembly of multiple polypeptides into a functional protein.
  • Peripheral proteins. Answer: Loosely attached to membranes by ionic/H-bond interactions.
  • 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.
  • 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.
  • Integral proteins. Answer: Proteins that span the membrane, often with hydrophobic helices.
  • X-ray crystallography. Answer: Determines 3D structure without using electromagnetic radiation directly.
  • SDS. Answer: Sodium dodecyl sulfate. Unfolds proteins and gives them uniform negative charge.
  • Ramachandran Plot. Answer: Shows favorable phi-psi angle combinations. 3 main "wells" for α-helices, ß-sheets, and left-handed α-helices.
  • Dialysis. Answer: Separates small molecules from proteins via a semi-permeable membrane.
  • Glycine Ramachandran Plot. Answer: Glycine can adopt more angles. (H's for R-group).
  • Size exclusion chromatography. Answer: Technique where larger proteins elute first.
  • Ion-exchange chromatography. Answer: Separates proteins by charge; proteins bind based on pI.
  • SDS-PAGE. Answer: Technique that separates proteins by size, with smaller proteins migrating faster.
  • Km. Answer: Substrate concentration at which the reaction rate is half of Vmax.
  • 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.
  • Vmax. Answer: Maximum rate of an enzyme-catalyzed reaction.
  • Competitive inhibitor. Answer: Increases Km without changing Vmax.
  • Non-competitive inhibitor. Answer: Decreases Vmax without changing Km.
  • Uncompetitive inhibitor. Answer: Decreases both Km and Vmax.
  • Transition State Analog. Answer: Molecules that mimic the high-energy transition state and bind enzymes tightly.
  • Michaelis-Menten plot. Answer: A hyperbolic curve representing the rate of enzyme reactions.
  • Lineweaver-Burk plot. Answer: A double reciprocal linear plot (1/V vs. 1/[S]).
  • 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.
  • Carbonic anhydrase. Answer: Enzyme that uses Zn2+ to activate water for nucleophilic attack.
  • 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.
  • Serine protease. Answer: Enzyme with a catalytic triad (Ser-His-Asp) that hydrolyzes peptide bonds.
  • ß-turns.
  • Hemoglobin 4° Structure. Answer: Tetramer. Dimer of dimers. α2ß2 tetramer.
  • O2 Saturation Curves. Answer: Myoglobin: hyperbolic curve; Hemoglobin: sigmoidal curve (cooperativity).
  • Kinases. Answer: Add phosphate groups.
  • Phosphatases. Answer: Remove phosphate groups.
  • α/ß Protein Folding. Answer: Less distinct areas of α and ß folding.
  • Muscle Contraction. Answer: Myosin uses ATP hydrolysis to 'walk' along actin filaments.
  • 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.
  • Temperature Denaturation of Protein. Answer: Midpoint of reaction is Tm.
  • Coupled Reactions. Answer: Unfavorable reactions driven by coupling to favorable ones (ATP hydrolysis).
  • Cooperative Protein Folding. Answer: Folding transition is sharp. More reversible.
  • Folding Funnel. Answer: Shows 3D version of 2D energy states. Lowest energy is stable protein. Rough funnel is less cooperative.
  • Protein-Protein Interfaces. 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. Answer: Weird interaction where aromatic rings stack on each other in positive interaction.
  • σ-hole. Answer: Methyl group has area of diminished electron density in center; attracts electronegative groups
  • ΔG Calculations. Answer: ΔG = ΔG°' + RT ln([products]/[reactants]). Coupled ΔGs are additive.
  • Glycosidic Linkages. Answer: α(1→4) in starch; β(1→4) in cellulose.
  • Reducing Sugars. Answer: Sugars with free anomeric carbon.
  • Fe Binding of O2. Answer: Fe2+ binds to O2 reversible. Fe3+ has an additional + charge and binds to O2 irreversibly. Fe3+ rusts in O2 rich environments.
  • Glycoproteins. Answer: Carbohydrates linked to Asn (N-linkage) or Ser/Thr/Tyr (O-linkage).
  • Lactate. Answer: Produced by anaerobic glycolysis (regenerates NAD+).
  • Ka for Binding. Answer: Ka = [PL] / [P][L]
  • Pyruvate Dehydrogenase Complex. Answer: Converts pyruvate → acetyl-CoA (needs TPP, lipoate, FAD,

Answer: Heme is in high-spin state. H2O is bound to heme.

  • Unsaturated Fats. Answer: More fluid, lower melting points.
  • Na+/K+ Pump. Answer: Active transporter: pumps 3 Na+ out, 2 K+ in, against gradient.
  • LDL. Answer: Delivers cholesterol to tissues ('bad cholesterol').
  • R-State. Answer: Heme is in low-spin state. O2 is bound to heme.
  • O2 Binding Event. Answer: O2 binds to T-state and changes the heme to R-state. Causes a 0.4Å movement of the iron.
  • HDL. Answer: Removes cholesterol from tissues ('good cholesterol').
  • Chylomicrons. Answer: Transport dietary fats.
  • Hemoglobin Binding Curve. Answer: 4 subunits present in hemoglobin that can be either T or R -state. Cooperative binding leads to a sigmoidal curve.
  • Binding Cooperativity. Answer: When one subunit of hemoglobin changes from T to R-state the other sites are more likely to change to R-state as well. Leads to sigmoidal graph.
  • Homotropic Regulation of Binding. Answer: Where a regulatory molecule is also the enzyme's substrate.
  • Heterotropic Regulation of Binding. Answer: Where an allosteric regulator is present that is not the enzyme's substrate.
  • B-Oxidation. Answer: Takes place in mitochondria; fatty acids → acetyl-CoA + NADH + FADH2.
  • Transaminases. Answer: Transfer amino groups to α-ketoglutarate to form glutamate.
  • Hill Plot. Answer: Turns sigmoid into straight lines. Slope = n (# of binding sites). Allows measurement of binding sites that are cooperative.
  • Electron Transport Chain. Answer: NADH → Complex I → CoQ → Complex III → Cyt C → Complex IV → O2.
  • FADH2 Entry. Answer: Enters at Complex II.
  • pH and Binding Affinity (Bohr Affect). Answer: As [H+] increases, Histidine group in hemoglobin becomes more protonated and protein shifts to T-state. O2 binding affinity decreases.
  • Overall Reaction. Answer: O2 → H2O, generates proton gradient.
  • Uncouplers. Answer: Dissipate proton gradient, halt ATP production.
  • Chargaff's Rules. Answer: %A = %T, %G = %C.
  • DNA Forms. Answer: A-DNA, B-DNA (common form), Z-DNA (zigzag shape).
  • CO2 binding in Hemoglobin. Answer: Forms carbonic acid that shifts hemoglobin to T-state. O2 binding affinity decreases. Used in the peripheral tissues.
  • Melting Temperature (Tm).

Answer: Slope changes by factor of α. Slope becomes αKm/Vmax.

  • Sanger Method. Answer: Chain-termination with ddNTPs.
  • Uncompetitive Inhibition Graph Changes Km and Vmax. Results in vertical shift up and down. Y-intercept becomes α'/Vmax X-intercept becomes -α'/Km. Answer: Does not change slope.
  • Mixed Inhibition Graph Pivot point is between X-intercept and Y-intercept.. Answer: Allosteric inhibitor that binds either E or ES.
  • Non-Competitive Inhibition Graph. Answer: Form of mixed inhibition where the pivot point is on the x-axis. Only happens when K1 is equal to K1'.
  • Ionophore. Answer: Hydrophobic molecule that binds to ions and carries them through cell membranes. Disrupts concentration gradients.
  • PCR. Answer: Denaturation → Annealing → Extension.
  • Restriction Enzymes. Answer: Cut DNA at specific sequences.
  • Cloning. Answer: Inserting DNA fragments into vectors.
  • DNA Replication. Answer: DNA polymerase synthesizes 5'→3', needs primer.
  • Reverse Transcriptase. Answer: Retroviruses use it to synthesize DNA from RNA.
  • Transcription. Answer: RNA polymerase makes mRNA from DNA.
  • Translation.

Answer: mRNA codons translated into protein at ribosome.

  • Fatty Acid Synthesis. Answer: Occurs in cytosol; requires ATP, NADPH, and acetyl-CoA.
  • ΔGtransport Equation. Answer: ΔGtransport = RTln([S]out / [S]in) + ZFΔΨ
  • Photosynthesis. Answer: Light energy → ATP + NADPH.
  • Pyranose vs. Furanose Furanose is a 5-membered ring.. Answer: Pyranose is a 6-membered ring.
  • Mutarotation. Answer: Conversion from α to ß forms of the sugar at the anomeric carbon.
  • Anomeric Carbon. Answer: Carbon that is cyclized. Always the same as the aldo or keto carbon in the linear form.
  • α vs. ß sugars ß form has -OR/OH group on the same side as the -CH2OH group.. Answer: α form has -OR/OH group opposite from the -CH2OH group.
  • Starch. Answer: Found in plants. D-glucose polysaccharide. "Amylose chain". Unbranched. Has reducing and non-reducing end.
  • Pentose Phosphate Pathway. Answer: Generates NADPH and ribose-5-phosphate.
  • Amylose Chain. Answer: Has α-1,4-linkages that produce a coiled helix similar to an α-helix. Has a reducing and non-reducing end.
  • Primary protein structure. Answer: The level of protein structure that is stabilized primarily by hydrogen bonds between backbone atoms.
  • Iron atom in hemoglobin. Answer: The iron atom in hemoglobin binds oxygen reversibly.
  • Glycogen. Answer: Found in animals. Branched every 8-12 residues and compact. Used as storage of saccharides in animals.
  • Cellulose. Answer: Comes from plants. Poly D-glucose. Formed from ß-1,4-linkage. Form sheets due to equatorial -OH groups that H-bond with other chains.
  • Chitin. Answer: Homopolymer of N-acetyl-ß-D-glucosamine. Have ß-1,4-linkages. Found in lobsters, squid beaks, beetle shells, etc.
  • Primary regulatory enzyme of glycolysis. Answer: The primary regulatory enzyme of glycolysis is Phosphofructokinase-1 (PFK-1).
  • Coenzyme used by pyruvate dehydrogenase complex. Answer: TPP is a coenzyme used by the pyruvate dehydrogenase complex.
  • Glycoproteins. Answer: Carbohydrates attached to a protein. Common outside of the cell. Attached at Ser, Thr, or Asn residues.
  • Membrane Translayer Flip-Flop. Answer: Typically slow, but can be sped up with Flippase, Floppase, or Scramblase.
  • Membrance Fluidity. Answer: Membrane must be fluid. Cis fats increase fluidity, trans fats decrease fluidity.
  • Fate of lactate under aerobic conditions. Answer: Under aerobic conditions in human cells, lactate is oxidized to pyruvate.
  • Intermediate in glycolysis with high-energy phosphate bond. Answer: 1,3-Bisphosphoglycerate contains a high-energy phosphate bond.
  • Type I Integral Membrane Protein. Answer: Membrane protein with C-terminus inside and N-terminus outside
  • Cofactor carrying electrons in electron transport chain. Answer: NAD+ carries electrons in the electron transport chain.
  • Type II Integral Membrane Protein. Answer: Membrane protein with N-terminus inside and C-terminus outside
  • Molecule binding to Fe²⁺ in heme of hemoglobin. Answer: O₂ binds to the Fe²⁺ in heme of hemoglobin.
  • Type III Integral Membrane Protein. Answer: Membrane protein that contains connected protein helices
  • Type IV Integral Membrane Protein. Answer: Membrane protein that contains unconnected protein helices
  • Effect of 2,3-BPG on hemoglobin. Answer: 2,3-BPG decreases oxygen affinity of hemoglobin.
  • Bacteriorhodopsin. Answer: Type III integral membrane protein with 7 connected helices.
  • Bond linking two monosaccharides in maltose. Answer: Maltose is linked by an α(1→4) glycosidic bond.
  • Best method for separating proteins by size under native conditions. Answer: Gel-filtration chromatography is best for separating proteins by size under native conditions.
  • ß-Barrel Membrane Protein. Answer: Can act as a large door. Whole proteins can fit inside.
  • Commonly phosphorylated amino acid side chain. Answer: Serine is commonly phosphorylated.

Answer: Condensed form of DNA. Deeper major groove and shallower minor groove.

  • Type of enzyme for insulin receptor. Answer: The insulin receptor is a kinase.
  • B-form DNA. Answer: Watson-Crick model DNA. Deep, wide major groove.
  • β-oxidation. Answer: Produces Acetyl-CoA directly.
  • Mass spectrometry. Answer: Determines protein mass most precisely.
  • PCR. Answer: The extension step synthesizes DNA.
  • Z-form DNA. Answer: Left-handed helical form of DNA
  • Size-exclusion column. Answer: A protein elutes first if it is very large.
  • Inverted Repeat in DNA TTAGCAC|GTGCTAA AATCGTG|CACGATT Forms a cruciform.. Answer: Found in double-strands.
  • Mirror Repeat in DNA/RNA TTAGCAC|GTGCTAA Forms a hairpin. Answer: Found in single-strands.
  • SDS-PAGE. Answer: A 50 kDa protein migrates further than expected if it has a large carbohydrate group.
  • Transition state. Answer: The peak energy of the reaction.
  • DNA UV Absorbtion. Answer: Absorbs UV light at 260nm.
  • Restriction Enzyme. Answer: Cuts DNA at specific restriction sites.
  • Cation exchange chromatography. Answer: A protein with pI 6.8 will bind and elute last in a buffer of pH 5.0.
  • DNA Base-paring A-T base pairs have 2 H-bonds. Answer: G-C base pairs have 3 H-bonds
  • Transition state analog. Answer: Structurally similar to the transition state.
  • GPCR (G-protein coupled receptor). Answer: α-helical integral membrane proteins. Is a αßɣ heterotrimer.
  • ß-adrenergic receptor. Answer: Prototype for all GPCR's. Bind adrenaline/epinephrine to stimulate breakdown of glycogen.
  • Step 1 of Epinephrine Signal Transduction. Answer: Epinephrine binds to its specific receptor
  • Step 2 of Epinephrine Signal Transduction. Answer: Hormone complex causes GDP bound to α-subunit to be replaced by GTP, activating α-subunit
  • Step 3 of Epinephrine Signal Transduction. Answer: Activated α-subunit separates from ßɣ-complex and moves to adenylyl cyclase, activating it.
  • Transferases. Answer: Enzyme class that catalyzes the transfer of phosphate groups.
  • Step 4 of Epinephrine Signal Transduction. Answer: Adenylyl cyclase catalyzes the formation of cAMP from ATP
  • Western blot. Answer: Detects protein size and presence.