Ch. 2
ELECTRON ROLES
1) Covalent Bonds strongest; e- shared between atoms make molecule; double, single, triple bond
2) Ions gain or lose e- to gain charges
CATIONS: Na+ K+ Ca+ H+ Mg+2 ANIONS: Cl- HCO3- HPO42- SO42-
3) High-Energy Electrons e- capture energy from environment to transfer to atom; energy carriers; NADH & FADH2
4) Free Radicals unstable; unpaired e-, highly reactive, breakdown bonds, neutralized by antioxidants (Vit. A,E,C); Cause: UV or smoke
CHEMICAL BONDS
1) Covalent Bonds atoms share e-
Nonpolar Molecules even distribution of e- ; lipid soluble; EX) Oil
Polar Molecules Regions of partial charge; positive and negative end; water soluble; EX) water
2) Non-covalent Bonds facilitate reversible binding of molecules
IONIC BONDS electrostatic attraction; atoms gain or lose e-, opposite charges attract
HYDROGEN BONDS Weak bond; between H atom and O, N, or F atom; Responsible for water surface tension
VAN DER WAALS FORCES weak nonspecific attractions of e-
NONCOVALENT INTERACTIONS
allow protein to associate reversible with other molecules, creating enzymes and substrates or signal receptors
Solubility ability to dissolve in a solvent
Hydrophilic soluble in water; polar or ionic molecules
Hydrophobic not soluble in water/lipid soluble; non polar molecules
Solution solute dissolved in solvent (water)
Concentration = solute amount / volume of solution
PROTEIN INTERACTIONS
1) Enzymes 4) Receptors 7) Regulatory Proteins
2) Membrane transporters 5) Binding proteins
3) Signal Molecules 6) Immunoglobulins
Ligand any molecule or ion that binds to another molecule
Substrates ligands that bind to enzymes and membrane transporters
Binding Site Active site; specifity, affinity, competition, saturation, molecular complimentarity
Affinity degree to which a protein is attached to a ligand
Law of Mass action concentration of reactant = to reaction; equilibrium constant
ESSENTIAL FOR BINDING ACTIVITY
1) COFACTORS required for ligand binding at site
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Dissociation
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