Bio exam #2

Proteins

• Amino acid: building block of proteins

• Peptide bond: covalent bond between amino acids

• Polypeptide: chain of <50 amino acids

• Protein: folded chain of >50 amino acids

• Primary structure: amino acid sequence

• Secondary structure: α‑helix or β‑sheet

• Tertiary structure: full 3D folding

• Quaternary structure: multiple polypeptides

• Denaturation: loss of protein shape/function

• Renaturation: regaining shape/function

Nucleic Acids

• Nucleotide: building block of DNA/RNA

• DNA: double‑stranded genetic material

• RNA: single‑stranded molecule for protein synthesis

• Transcription: DNA → mRNA

• Translation: mRNA → protein

• Phosphodiester bond: sugar ↔ phosphate

• Glycosidic bond: sugar ↔ base

• Hydrogen bond: base pairing

• Purine: double ring (A, G)

• Pyrimidine: single ring (C, T/U)

Cell Structure

• Plasma membrane: boundary of cell

• Cytoplasm: fluid interior

• Ribosome: protein synthesis

• Nucleoid: DNA region in prokaryotes

• Organelle: specialized cell structure

• Prokaryote: no nucleus

• Eukaryote: nucleus + organelles

• Surface area‑to‑volume ratio: limits cell size

Cell Membrane

• Phospholipid: amphipathic molecule

• Integral protein: embedded in membrane

• Peripheral protein: surface‑attached

• Cholesterol: regulates fluidity

• Glycoprotein: protein + carbohydrate

• Glycolipid: lipid + carbohydrate

• Selective permeability: controls entry/exit

Transport

• Diffusion: high → low concentration

• Osmosis: water diffusion

• Passive transport: no energy

• Facilitated diffusion: uses channels/carriers

• Active transport: requires ATP

• Endocytosis: cell takes in material

• Isotonic: equal solute

• Hypotonic: lower solute outside

• Hypertonic: higher solute outside