MCAT Basics (from MedSchoolCoach) Biomolecule Structure, Naming, And Function
Sep 16, 2025
Dive into the intricate world of biomolecules, starting with the structural differences between glucose and fructose. Unravel the complexities of glycosidic linkages and learn how fatty acids shape cell membrane architecture. Discover cholesterol's crucial role in membrane stability and the contrasting impacts of LDL and HDL on heart health. Explore the essential functions of steroids and nucleotides, along with the foundational structures of DNA and RNA. Finally, uncover the unique properties of sphingolipids and signaling molecules like eicosanoids.
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Starch And Glycogen Branching Patterns
- Plants store glucose as starch: amylose is unbranched alpha-1,4 chains while amylopectin is branched via alpha-1,6 linkages.
- Glycogen resembles amylopectin but has even more frequent alpha-1,6 branch points.
Fatty Acid Roles And Membrane Effects
- Fatty acids form triglycerides (glycerol + three tails) and phospholipids (glycerol, two tails, phosphate head).
- Saturated tails pack tightly; unsaturated tails kink and increase membrane fluidity.
Cholesterol As Membrane Thermostat
- Cholesterol acts bidirectionally: it prevents membrane stiffening at low temperatures and reduces fluidity at high temperatures.
- It wedges between phospholipids to space them at cold and increases van der Waals packing at heat.