Overview
This lecture covers essential vocabulary and concepts on biomolecules, chemical bonds, water properties, macromolecule structure and function, and molecular biology basics for AP Biology Unit 1.
Chemical Bonds and Properties of Water
- Electronegativity is the attraction strength of an atom for electrons (oxygen > hydrogen).
- Covalent bonds involve electron sharing; hydrogen bonds are weak attractions between hydrogen and electronegative atoms.
- Polar molecules have unequal electron sharing and partial charges, enabling water interactions.
- Capillary action is water rising against gravity in thin tubes, caused by adhesion, cohesion, and surface tension.
- Cohesion is attraction between same molecules; adhesion is between different substances.
- Surface tension is strong cohesion at the liquid surface; meniscus is the liquid's curved surface in a container.
- Ice floats because it's less dense than water; freezing expands water molecules into a crystal structure.
- Water's high specific heat helps maintain homeostasis and climate stability; high heat of vaporization cools organisms and stabilizes environments.
Atomic Structure and Macromolecules
- Atomic mass unit (amu): proton/neutron = 1 amu.
- Valence electrons are in the atom's outer shell.
- Ionic bonds form when atoms transfer electrons, resulting in cations (positive) and anions (negative).
- Organic molecules contain carbon.
Macromolecule Types and Functions
- Carbohydrates: monomer is monosaccharide, polymer is polysaccharide; provide energy and structural support.
- Proteins: monomer is amino acid, polymer is polypeptide; functions include tissue building, enzymes, and cell communication.
- Nucleic acids: monomer is nucleotide, polymer is DNA/RNA; store and transmit genetic info.
- Lipids: built from glycerol and fatty acids; store energy, insulate, compose membranes; no true monomers.
Proteins: Structure and Function
- Proteins have primary (sequence), secondary (a-helix, b-sheet), tertiary (3D folding), and quaternary (multi-chain) structures.
- Peptide bonds connect amino acids.
- Protein denaturation disrupts bonds and function.
- R-group interactions determine folding and function.
- Four amino acid parts: hydrogen atom, amino group, carboxyl group, R group.
Nucleic Acids and Gene Expression
- DNA's sugar is deoxyribose (stable); RNA's is ribose (reactive).
- DNA is double-stranded; RNA is single-stranded.
- Nucleotides consist of a sugar, phosphate group, and nitrogenous base.
- Purines have two rings (A, G); pyrimidines have one ring (C, T, U).
- Codons (mRNA) and anticodons (tRNA) are three-base sequences.
- Transcription copies DNA into mRNA; translation builds protein from mRNA, tRNA, and ribosomes.
Lipids: Types and Properties
- Types: triglycerides, phospholipids, steroids, fats, oils, waxes.
- Saturated fats have single bonds (solid); unsaturated fats have double bonds (liquid, healthier).
- Cis fats are bent; trans fats are straight and unhealthy.
Elements in Biomolecules
- Proteins: C, H, O, N (sometimes S)
- Nucleic acids: C, H, O, N, P
- Carbohydrates: C, H, O
- Lipids: C, H, O (sometimes P)
- Nitrogen found in proteins/nucleic acids; phosphorus in nucleic acids/phospholipids; sulfur only in proteins.
Key Terms & Definitions
- Hydrolysis — breaking polymers by adding water.
- Dehydration synthesis — joining monomers by removing water.
- Dimer/trimer/polymer — molecule with 2/3/many monomers.
- Solvent — substance that dissolves solutes.
- Monomer — building block of polymers.
Action Items / Next Steps
- Review all vocabulary and definitions.
- Practice drawing and labeling protein and nucleic acid structures.
- Study the differences between carbohydrate, protein, nucleic acid, and lipid structure and function.