Ch 2 - Biochemistry

INORGANIC COMPOUNDS lack carbon (with the exception of carbon dioxide) and tend to be simple, small molecules water, salts, most acids and bases

Water Important Properties: High heat capacity - prevents sudden change in body temp that could result from sun exposure, winter winds, vigorous exercise, etc Polarity/solvent properties - “universal solvent” allows chemicals to react in solution like blood plasma; also important in lubrication, saliva, serous fluids and synovial fluids Chemical Reactivity - hydrolysis reactions, water molecules added to bonds of foods or large molecules Cushioning - protective function, i.e. cerebrospinal fluid and amniotic fluid

Salts Most plentiful salts in body contain Ca and P, found in bones and teeth All salts in the body are electrolytes - dissociate into ions and conduct an electrical charge in solution Na and K ions are essential for nerve impulses Fe forms part of the hemoglobin molecules Ionic (electrolyte) balance is essential to homeostasis

Acids and Bases Acids - sour taste, release H+ ions, proton donors; hydrochloric acid, acetic acid, carbonic acid Bases - bitter taste, release OH-, proton acceptors; sodium hydroxide, bicarbonate Neutralization Rxn: Acid + Base --> Water + Salt pH scale, 0-14, 1 pH unit change = 10X change in [H+] Weak acids and bases are important buffers in body fluids

ORGANIC COMPOUNDS Carbon-containing compounds, large covalently bonded molecules Carbohydrates, Lipids, Proteins, and Nucleic Acids

Carbohydrates contain carbon, hydrogen, and oxygen; end in -ose usually in ratio of 1:2:1 (glucose is C6H12O6; ribose is C5H10O5) Glucose (blood sugar) is called the universal cellular fuel. 1 g carb= 4 Calories monosaccharide - one unit (simple sugars), single chain or single ring; glucose, fructose, galactose, ribose, deoxyribose disaccharide - double sugars; sucrose (glucose-fructose), lactose (glucose- galactose), maltose (glucose-glucose) polysaccharide - many sugars; long branching chains, used for storage (not sweet); starch (plants), glycogen (animals)

Carbohydrates

Dehydration synthesis and hydrolysis

Lipids most abundant lipids in body: fats, phospholipids, steroids carbon, hydrogen, and oxygen molecules (mostly C and H) building blocks: fatty acids and glycerol most are insoluble in water 1 g fat = 9 calories large amount of energy, insulation, protection saturated-animal fats, butter, lard, grease (solid at room temp) unsaturated-most plant oils, olive oil, fish oils (liquid at room temp)

Lipids Triglycerides (fats) - insulation and energy storage Phospholipids - main component in cell membranes Steroids - (cholesterol, Vit D, estrogen, cortisone) many functions - stimulate growth, develop repro organs, sexual function, anti-inflammatory, essential in brain function Waxes

Proteins building block = amino acids (C, H, O, N); amine group, acid group, and variable R-group (makes a.a. chemically unique) peptide = short chain of amino acids; polypeptide = long chain of a.a. Humans must have 20 different a.a., but can produce only 10, others must come from food Structure is VERY important for function - pH and temperature can affect shape Food sources: legumes, eggs, milk, fish, poultry, meat 1 g protein = 4 Calories

Protein Functions Over 50% of organic matter in body is protein structural or fibrous proteins (bones, ligaments, cartilage, tendons,skin) - collagen, keratin Globular or functional proteins: defense against infection - antibodies hormones - insulin, prolactin, nerve growth factor transport - hemoglobin histones - “spool” around which DNA winds ENZYMES - speed up chemical reactions in body, help break down molecules

Amino Acid Sequence One wrong a.a. sequence in the hemoglobin protein=mis-shapen RBC and severely limits function

Enzymes most end in -ase substrate = molecule the enzyme acts on active site = location where enzyme fits with substrate

Nucleic Acids made of nucleotides (pentose (5-C) sugar, phosphate group, nitrogen base); in all cells bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U) deoxyribonucleic acid (DNA) - double helix; genetic material; replicates itself; provides instruction for building every protein in body A- T, G-C ribonucleic acid (RNA) - single strand; makes proteins in the cell A-U, G-C

Adenosine Triphosphate (ATP) form of energy used by all cells modified nucleotide: adenosine base, ribose sugar, three phosphate groups when glucose is oxidized, energy is captured by ATP and stored high-energy phosphate bonds are hydrolyzed to release energy to do work