How is biochemistry different from organic chemistry?

Organic chemistry focuses on reaction mechanisms and synthesis in controlled conditions. Biochemistry applies that mechanistic thinking to aqueous, buffered, catalyzed reactions at 37°C, and adds thermodynamic and kinetic analysis of enzymes plus the logic of how pathways are regulated. You use orgo constantly, but the questions asked are different.

Do I actually have to memorize every enzyme and intermediate in glycolysis and the citric acid cycle?

Most intro courses expect the intermediates, the enzymes at regulated steps, and the energy yields. Sessions focus on learning the pathways as chemical logic — where carbons are lost, where phosphate is added, where oxidation occurs — because that structure makes recall more reliable than rote lists and handles questions your flashcards did not anticipate.

What math do I need for enzyme kinetics?

Algebra and logarithms. You need to rearrange the Michaelis-Menten equation, read double-reciprocal plots, and handle Henderson-Hasselbalch. Some courses show the steady-state derivation; understanding where the assumptions enter matters more than reproducing the algebra from scratch.

Can this help if I am behind after failing the first exam?

Sessions can start by diagnosing which specific ideas broke — often pKa reasoning or the standard-state free energy issue — and rebuilding from there before moving to new material. There is no guaranteed outcome, but working problems aloud tends to expose gaps faster than rereading notes.

Biochemistry

College Intro · Science

Biochemistry at the introductory college level asks you to explain how cells work using chemical reasoning: why a side chain is charged at pH 7.4, why an enzyme saturates, why glucose oxidation yields the ATP it does. It sits between organic chemistry and cell biology, borrowing mechanism and thermodynamics from one and physiological context from the other. Sessions with Evelyn Tutor are spoken, one-on-one, and built around working through problems out loud — deriving Henderson-Hasselbalch answers, reasoning through a Lineweaver-Burk plot, or tracing carbon atoms through the citric acid cycle — rather than listening to a lecture replay.

Start a session on Biochemistry

What this covers

Amino acid structures, pKa values, and predicting net charge and isoelectric point at a given pH; buffer calculations with Henderson-Hasselbalch
Protein structure from primary to quaternary: peptide bond geometry, Ramachandran-allowed conformations, the forces driving folding, and cooperative binding in hemoglobin vs. myoglobin
Michaelis-Menten kinetics: deriving and interpreting Km, Vmax, and kcat/Km, plus distinguishing competitive, uncompetitive, and mixed inhibition from kinetic data
Bioenergetics: standard-state vs. actual free energy change, reaction coupling through ATP hydrolysis, and reduction potentials in electron transport
Central metabolism — glycolysis, pyruvate oxidation, the citric acid cycle, oxidative phosphorylation, glycogen metabolism and fatty acid oxidation — with emphasis on committed steps and allosteric regulation
Enzyme mechanism and cofactor chemistry: catalytic strategies (acid-base, covalent, metal-ion), and what NAD+, FAD, coenzyme A, and thiamine pyrophosphate actually do chemically

Where learners get stuck

Treating Km as a direct measure of binding affinity in all cases: Intro courses introduce Km as 'the substrate concentration at half Vmax' and then loosely call it affinity. Km only approximates the dissociation constant when the catalytic step is slow relative to substrate release. Students who never see that assumption stated cannot explain why kcat/Km, not Km, is the right measure of catalytic efficiency.
Confusing ΔG°' with ΔG when judging whether a step in a pathway runs forward: Tables list standard free energies, so students conclude that steps with positive ΔG°' cannot occur. In a cell, mass action ratios far from standard state make those steps proceed readily — this is exactly why the aldolase reaction in glycolysis works. The fix is always writing out the concentration term, not memorizing which steps are 'irreversible'.
Deciding amino acid charge from the side chain name rather than comparing pH to pKa: Students memorize 'lysine is basic, positive' and then misassign charge at pH 11, or forget the alpha-amino and alpha-carboxyl groups contribute at the termini. Working the comparison explicitly — protonated below pKa, deprotonated above — every single time fixes this faster than any mnemonic.
Memorizing pathway intermediates as a list without tracking carbon count, redox state, or phosphorylation: Flashcards reward name recall, but exam questions ask which carbons appear as CO2, how many NADH per turn, or where a labeled atom ends up. Structures make sense as a sequence of chemical transformations — oxidation, isomerization, cleavage — and that framing is what makes them recallable under pressure.

What a session looks like

You talk through problems aloud while Evelyn asks the follow-up questions a study partner would. A typical session might start with a kinetics dataset you have to classify by inhibitor type, move into explaining why the answer is what it is, then check whether you can predict what happens to the plot if the inhibitor concentration doubles. For metabolism, you are asked to reconstruct a pathway segment from memory and justify each step's chemistry rather than recite it. Wrong answers get probed, not corrected outright — the aim is finding which assumption broke.

Helpful to know first

One year of general chemistry, including equilibrium, acids and bases, and thermodynamics (ΔG, ΔH, ΔS)
At least one semester of organic chemistry: functional groups, nucleophiles and electrophiles, resonance, and basic reaction mechanisms
Familiarity with logarithms and the ability to rearrange algebraic equations; calculus is not required for most intro courses
Introductory biology helps for cellular context but is not strictly necessary

Questions

How is biochemistry different from organic chemistry?: Organic chemistry focuses on reaction mechanisms and synthesis in controlled conditions. Biochemistry applies that mechanistic thinking to aqueous, buffered, catalyzed reactions at 37°C, and adds thermodynamic and kinetic analysis of enzymes plus the logic of how pathways are regulated. You use orgo constantly, but the questions asked are different.
Do I actually have to memorize every enzyme and intermediate in glycolysis and the citric acid cycle?: Most intro courses expect the intermediates, the enzymes at regulated steps, and the energy yields. Sessions focus on learning the pathways as chemical logic — where carbons are lost, where phosphate is added, where oxidation occurs — because that structure makes recall more reliable than rote lists and handles questions your flashcards did not anticipate.
What math do I need for enzyme kinetics?: Algebra and logarithms. You need to rearrange the Michaelis-Menten equation, read double-reciprocal plots, and handle Henderson-Hasselbalch. Some courses show the steady-state derivation; understanding where the assumptions enter matters more than reproducing the algebra from scratch.
Can this help if I am behind after failing the first exam?: Sessions can start by diagnosing which specific ideas broke — often pKa reasoning or the standard-state free energy issue — and rebuilding from there before moving to new material. There is no guaranteed outcome, but working problems aloud tends to expose gaps faster than rereading notes.