Introduction to Biochemistry Bicarbonate buffering system maintains blood at one critical pH Mad cow disease is caused by a misfolded protein Electrons found in the lowest available energy level ground state electrons move to higher excited Isotopes vary in the number of neutrons same number electrons chemically iden tical Half life radioactive decay Carbon 14 measures age of fossils and earth Radioisotopes radioactive iodine diagnoses and treats disease of thyroid gland tracer traces path of carbon dioxide in a metabolic pathway Energy is released when a bond is formed energy is supplied to break a bond Ionic transfer of electrons anion gains electrons cation loses electrons tions Covalent atoms share electrons forms molecule nonpolar shared equally diatomic molecules O2 symmetrical weak attrac polar shared unequally CO2 asymmetrical strong attractions Water is highly polar hydrogen bonding H O high specific heat resists changes in temperature and moderates climate marine biome most stable high heat of vaporization universal solvent all polar and ionic substances strong cohe sion tension transpirational pull cohesion tension water moves up without ex penditure of energy capillary action combined forces of cohesion and adhesion surface tension walk on water without breaking surface ice is LESS DENSE than water floats spring overturn is the cycling of nutrients in a lake The value of the pH is the negative log of the hydrogen ion concentration in moles per liter Human blood 7 4 As the H concentration increases the pH decreases Buffers resist changes in pH ex bicarbonate ion in human blood Isomers have same molecular formula but different structures Structural differ in covalent arrangement of atoms Geometric differ in spatial arrangement around double bonds Enantiomers mirror images of each other Organic compounds contain carbon Carbohydrates quick energy Monosaccharide glucose galactose fructose Disaccharide formed with dehydration synthesis condensation removal of H2O Maltose glucose glucose Sucrose glucose fructose Lactose glucose galactose Hydrolysis is the breakdown of a compound opposite of dehydration synthesis Polysaccharide cellulose plant structure cell wall starch plant storage amy lose amylopectin chitin animal structure exoskeleton glycogen animal storage Lipids fats oils waxes steroids energy storage phospholipids membrane hor mones 1 glycerol alcohol and 3 fatty acids hydrocarbon chain w carboxyl Saturated animals solid at room temp heart disease single bonds between carbon atoms Unsaturated plants liquid at room temp good dietary fats double bond w removal of H atoms Steroid four fused rings ex cholesterol plasma membrane of animal cells Proteins growth and repair defense catalyze chemical reactions fish poultry meat Amino acids carboxyl amine and variable groups joined by peptide bonds Structure 1 2 Primary linear sequence of amino acids ex sickle cell anemia substitution of one amino acid for another in hemoglobin Fred Sanger was the first to sequence a protein insulin Secondary hydrogen bonding within polypeptide molecule how it coils folds into alpha helix or beta pleated sheet ex fi brous proteins keratin makes up human hair mostly alpha helixes 3 4 Tertiary 3D shape of protein determines specificity Quaternary more than one polypeptide chain ex hemoglobin 4 chain each form heme group Protein folding problem form of molecule determines function chaperone proteins assist in folding other proteins Nucleic Acids carry heredity information repeating nucleotides phosphate 5 car bon sugar nitrogen Functional groups amino amine NH2 carboxyl acid COOH hydroxyl alcohol OH carbonyl aldehyde ketone COH sulfhydryl SH phosphate PO4 Law of conservation of energy energy cannot be created or destroyed only transferred first law of thermodynamics second law universe becomes more and more disordered greater entropy metabolism is the sum of all chemical reac tions in cells Enzymes are catalytic proteins that speed up reactions by lowering the energy of activation globular proteins that exhibit tertiary structure substrate specific in duced fit model lock and key reused after reaction named after substrate ends in ase catalyze reactions in both directions require assistance from cofac tors inorganic and coenzymes vitamins efficiency affected by pH and temp denature Competitive inhibition competes for same active site inhibitors reduce the productivity of enzymes by preventing the substrate from combining with the enzyme Noncompetitive inhibition enzyme contains more than one active site substrates do not resemble each other ex operon affects transcription via RNA polymerase Allosteric inhibition two active sites one for substrate and one for in hibitor ex Phosphofructokinase glycolysis prod pyruvic acid feedback inhibition metabolic pathway is switched off by end product prevents call from wasting energy resources