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Biology 219 – Human Physiology Biomolecules Clemens Text: Ch 2 A. Carbohydrates general formula: (CH2O)n e.g., glucose - C6H12O6 soluble in H2O (many polar –OH groups) major energy source for most cells; required by CNS 1. Monosaccharides (simple sugars) - energy metabolism: glucose + 6 O2 → 6 CO2 + 6 H2O + energy (→ ATP) - building blocks of polysaccharides and nucleotides ring structures: O pentoses (5C) ribose, deoxyribose hexoses (6C) glucose, galactose, fructose O 2. Disaccharides maltose = gluc–gluc; sucrose = gluc–fruc; lactose = gluc–galac 3. Polysaccharides - energy storage molecules starch (plants) glycogen (animals, stored in liver and muscle) - structural polysaccharides cellulose (plant fiber) chitin GAGs (connective tissues - EC matrix) B. Lipids mostly non-polar organic molecules rich in C-H and C-C bonds low solubility in H2O 1. Fatty acids - basic building blocks of lipids long-chain hydrocarbons with carboxyl end COOH saturated fatty acids: contain all C-C single bonds - hydrocarbon chains pack closely → more solid (e.g., animal fat) unsaturated fatty acids: contain C=C double bond(s) (monounsaturated, polyunsaturated) - “kink” in the chain → more liquid (e.g., vegetable oil) 2. Triglycerides (triacylglycerols) 3 fatty acids + glycerol - energy-rich molecules (= high in calories) ~ 2X more energy than carbohydrates per gram - insoluble in H2O - body fat (adipose tissue) functions for energy storage 3. Phospholipids 2 fatty acids + glycerol + phosphate group - amphipathic molecules - polar (head) and non-polar (tail) ends e.g., phosphatidylcholine (lecithin) - phospholipid bilayer forms the basic structure of the plasma membrane phospholipid heads contains charged/polar phosphate groups non-polar tails contain saturated and unsaturated fatty acids 4. Steroids cholesterol and derivatives; 4-ring structure - cholesterol is a component of the cell membrane - steroid hormones: cortisol, aldosterone, testosterone, estrogen 5. Eicosanoids modified fatty acids with a ring (e.g., prostaglandins) - function in intercellular signaling (paracrine agents) - vasomotor effects (constriction or dilation), inflammation, pain Biology 219 – Human Physiology C. Amino Acids and Proteins 1. Amino acids Clemens H H2N-C-COOH R contain amino group, carboxyl group, central C atom, H atom, R group - R groups are variable: non-polar, polar, acidic (neg. charged), basic (pos. charged) - 20 different R groups → 20 different amino acids in proteins 2. Peptides and polypeptides polymers of amino acids - chains formed by amino-carboxyl links - peptide bond - strong covalent bond joins adjacent a.a.s - R groups stick out from the chain 3. Proteins > 50 amino acids, complex 3-dimensionalstructure: primary (1°) structure - “linear” amino acid sequence (peptide bonds) secondary (2°) structure - simple coiling/folding of the chain, e.g., alpha helix (H bonds) tertiary (3°) structure - higher order 3-dimensional folding (R-group interactions) quaternary (4°) structure - interaction among multiple protein subunits D. Nucleotides and Nucleic Acids (DNA and RNA) - information molecules - store and transfer genetic information 1. Nucleotides - 3-part molecule, building blocks of DNA and RNA a. pentose sugar b. phosphate group c. nitrogenous base purines (double ring): adenine (A), guanine (G) pyrimidines (single ring): cytosine (C), thymine (T), uracil (U) 2. DNA - sugar = deoxyribose S-A T-S - double stranded, double-helix P P sugar-phosphate covalent bonds form “backbone” S-G C-S bases point inward P P - base pairing: A=T S-C G-S G≡C P P hydrogen bonds between complementary bases S-T A-S 3. RNA - sugar = ribose - mostly single stranded (higher-level structures in tRNA and rRNA) - base pairing: A=U, G≡C Classes of RNA messenger (mRNA) transfer (tRNA) ribosomal (rRNA) 4. Other nucleotides/ nucleotide derivatives ATP - energy “currency” molecule GTP, cAMP - regulatory and cell signaling molecules NADH, FADH2 - coenzymes, carriers of electrons and H in cellular respiration