Biochemistry Summary - MCAT Biochemistry-Macromolecules, Kinetics, Thermodynamics, & The Plasma Membrane - Amino Acids & Proteins - Carbohydrates

Oct 13, 2026

Biochemistry Summary covers high-yield MCAT biochemistry topics spanning macromolecules and core chemistry foundations. It links monomer classes to their polymers and specifies the main bond types forming macromolecules. Amino acids and proteins are organized by primary, secondary, tertiary, and quaternary structure, including pH-dependent charge behavior and the concept of isoelectric point using pKa averaging. Carbohydrates are summarized by aldehyde/ketone classification, mono-/di-/polysaccharide definitions, stereochemical absolute configuration, and Haworth projection interpretation for anomeric orientation.

LanguageEnglish

CategoryPaper Templates

FormatPDF

Pages18

Reading Time6 min

AccessFree to download

Building blocks of macromolecules

Monomers to polymers and bond types

Amino acids and proteins

Amino acid structure and ionization

Protein structure levels

Isoelectric point (pI)

Carbohydrates

Monosaccharides, disaccharides, polysaccharides

Absolute configuration and Haworth projections

[MCAT-Prep.com](MCAT-Prep.com) Biochemistry Summary Note: Summaries are most helpful post-content review. MCAT Biochemistry-Macromolecules, Kinetics, Thermodynamics, & The Plasma Membrane | Building block | Polymerizes to form… | Chemical bonds | Macromolecule | | --- | --- | --- | --- | | Monomers | Dimer, trimer, tetramer, oligomers, etc . | Covalent* bonds | Polymer | | Amino acids | Dipeptide, tripeptide, tetra/oligopeptide, etc | Peptide bonds | Polypeptide, protein
(e.g. insulin, hemoglobin) | | Monosaccharides (‘simple sugars’**) | Disaccharide, tri/tetra/ oligosaccharide, etc . | Glycosidic bonds | Polysaccharide
(e.g. starch, glycogen) | | Nucleotides | Nucleotide dimer, tri/tetra/oligomer, etc . | Phosphodiester bonds | Polynucleotides, nucleic acids (e.g. DNA, RNA) | *There are exceptions. For example, in certain circumstances polypeptides are considered monomers and they may bond non-covalently to form dimers (i.e. higher orders of protein structure) . **Note that disaccharides are also sugars (i.e. sucrose is a glucose-fructose dimer known as ‘table sugar’; lactose is a glucose-galactose known as ‘milk sugar’) . MCAT Biochemistry Macromolecules: Summary I -Amino Acids & Proteins The current MCAT regularly has questions which require previous knowledge of the structures, features (including changes in charge with pH), 3- and 1-letter abbreviations of the 20 common protein-generating amino acids, etc. The 20 Standard Amino Acids . A red asterix * is used to indicate the 9 essential amino acids . Notice that if the acidic electrically charged amino acids are fully protonated, the overall charge would be +1 but if fully deprotonated, the overall charge would be-2. The opposite being true for basic amino acids: If fully protonated, the overall charge would be +2 but if fully deprotonated, the overall charge would be-1. These cases are different than for the average amino acid. Note the inset (in the red box) which shows the general structure for an amino acid in both the (1) un-ionized and (2) zwitterionic forms . For the latter, note the resonance stabilized carboxylate anion in red, the primary ammonium ion in blue, and the variable R group in green. MCAT prep • MCAT prep courses • MCAT practice tests MCAT-Prep.com The Only Prep You Need™ Page 1 of 18 [MCAT-Prep.com](MCAT-Prep.com) Biochemistry Summary Helpful Mnemonics for One-Letter Amino Acid Abbreviations: Alanine, aRginine, asparagiNe, asparDic acid [aspartic acid], Cysteine, Qutamine [glutamine], glutamEc acid [glutamic acid], Glycine, Histidine, Isoleucine, Leucine, Kysine [lysine], Methionine, Fenylalanine [phenylalanine], Proline, Serine, Threonine, tWyptophan [tryptophan], tYrosine, Valine Nonpolar Amino Acids = G A P V W L I M F or Gap V.W. Lymph (lymph is important in fatty acid transport think fatty acid tails are nonpolar) Polar Uncharged Amino Acids = S T Y C N Q or Stick Nick (stick like a “pole” think polar) Electric Amino Acids = D E H K R or Dee Hicker (dee hicker like deelectric think electric) To be more precise, for the Polar Charged Amino Acids: Dee Negative, Hicker Positive, D(-) E(-) H(+) K(+) R(+) General Principles of Proteins l Primary structure m Sequence of amino acids encoded by DNA and linked to each other through covalent bonds (including disulfide bonds) l Secondary structure m Orderly inter-or intramolecular hydrogen bonding of the protein chain m Usually organized in a stable a-helix or a β-pleated sheet l Tertiary structure m Further folding of the protein molecule onto itself m 3D shape (spatial organization) of an entire protein molecule l Quaternary structure m 2 or more protein chains bonded together by noncovalent bonds Levels of Protein Organization Page 2 of 18 MCAT BIOCHEMISTRY SUMMARY [MCAT-Prep.com](MCAT-Prep.com) Biochemistry Summary l Isoelectric point (pI) m pH at which a given amino acid will be neutral (have no net charge) m Average of

FAQs

How do monomers polymerize into major macromolecule classes in MCAT biochemistry?

Monomers form polymers through specific bond types: monomers polymerize via covalent bonds, amino acids via peptide bonds, monosaccharides via glycosidic bonds, and nucleotides via phosphodiester bonds.

What determines whether an amino acid is neutral, and how is isoelectric point (pI) calculated?

The isoelectric point is the pH where an amino acid has no net charge. It is calculated as the average of two pKa values: pI = (pKa1 + pKa2)/2.

How are carbohydrates classified and named in this summary?

Carbohydrates are described by carbonyl type (aldose vs ketose) and by size (triose, tetrose, pentose, hexose) using the number of carbons. The “-ose” suffix denotes sugar.

Oct 13, 2026

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