@drlorimarie: The Four Levels Of Protein Structure 🧬 Each level is held together by something different and that's what the MCAT tests. Primary — peptide bonds The amino acid sequence. Peptide bonds between the carboxyl of one amino acid and the amino group of the next. Encoded by your genes. Determines everything downstream. Secondary — backbone hydrogen bonds Alpha helices and beta sheets. Hydrogen bonds between the carbonyl O of one amino acid and the amide H of another. Backbone, not side chains. Tertiary — the hydrophobic effect + side chain interactions 3D folding of the whole polypeptide. Nonpolar side chains cluster inside, polar side chains face the surface. Stabilized by H bonds, ionic interactions, van der Waals, and disulfide bonds. Quaternary — assembly of multiple subunits Same stabilizing interactions as tertiary, but between subunits. Hemoglobin is the classic example with four subunits. When the MCAT asks how denaturation affects a protein, it's asking which level is being disrupted and which interactions break first. Save this for your next biochem review. #mcatprep #biochem #protein #premed #mcat

Dr. Lori Marie | MCAT Prep

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Sunday 21 June 2026 17:56:49 GMT