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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Steroid Structure Enables Nuclear Signaling
- Steroids share a four-ring hydrocarbon backbone that makes them small and highly nonpolar.
- Their hydrophobicity lets them diffuse across membranes and alter transcription inside the nucleus.
Nucleotide Parts And Base Classes
- Nucleotides contain a nitrogenous base, a five-carbon sugar, and one or more phosphates.
- Purines are two-ring A/G and pyrimidines are one-ring C/U/T, and ribose has a 2' OH while deoxyribose lacks it.
ATP Phosphate Naming And Release Order
- ATP is adenosine plus three phosphate groups named alpha (closest), beta, and gamma (terminal).
- The gamma phosphate is lost first, then beta, leaving the more tightly held alpha phosphate last.