Essay About Strong Acids And H2

Biochemistry Exam I Study Guide
Biochemistry Exam I Study GuideCHEMISTRY REVIEWChemical BondingElectrovalent or Ionic BondsValence electrons are transferred  from atom to anotherForms charged atoms (ions)Atom that loses electrons becomes a cation (+ positively charged)Atom that gains electrons becomes an anion (negatively charged)NaClNa+ has 1 valence electronCl- has 7 valence electronsNa’s valence electron is transferred to Cl to complete octet and becomes cation; Cl = anionBonds are formed by attraction on + and – chargesWeaker than covalent bondingBonds dissociate when dissolved in water (b/c water is a polar solvent; “like dissolves like”)Covalent BondsBonds that are formed when atoms share valence electronsCan be polar or nonpolarNonpolarShare electrons equallyi.e. H2 or O2PolarShare electrons unequallyCreates dipole – have + and – polarityElectrons are pulled toward the more electronegative atomi.e. H2OCoordinate CovalentBond formed when one atom provides both electrons in a shared pairi.e. NH3 has a lone pair of electrons that can partially contribute to make another bondHydrogen BondsWhen H forms polar bond with another atom it takes on a slight + charge (dipole), which makes it attracted to any nearby negatively charged atomsForms between adjacent H2OsAll life is due to Hydrogen bondingWater as a solventDissolves polar compounds due to its polar activityAmphipathic – chemical compound possessing both hydrophilic (lipophobic) and hydrophobic (lipophilic) propertiesHydrophilic/lipopobic compounds are dissolvable in waterHydrophobic/lipophilic compounds are not dissolvable in waterTonicityIf a cell is placed in a hypertonic solution, the cell shrinks as water moves outside of the cell due to increased solute concentration outside the cellIf a cell is placed in a hypotonic solution, the cell inflates and could potentially burst as water moves inside the cell due to the decreased solute concentration outside the cellIf a cell is placed in an isotonic solution, water is moving in and out of the cell as equal rates and is considered to be in equilibriumAcidsCompounds that release protons (H+) in a solutionProton “donors”Strong acids – acids that quickly and completely dissociate when placed in H2OHClH2SO4H3PO4Weak acids – acids that dissociate slowly when placed in H2O***regulators in changes of alkalinity/acidity in the human system***H2CO3 BasesCompounds that accepts protons (H+) or lowers H+ levels of a solution or releases hydroxyl ions (OH-)Proton “acceptors”Strong bases NaOHCa(OH)2Weak baseNH4OHBuffersSolution composed of a weak acid and its conjugate baseWhen small amounts of strong acids or bases are added to it, the pH only changes a little by combining with or releasing H+Important buffer systems (help regulate pH inside the body (pH = 7.4 ± 1.0))Hemoglobin bufferBicarbonate bufferH2CO3  ⬄ H+ + HCO3-weak acid             conj. BasePhosphate bufferProtein bufferDissociation constant (Ka)Ka = [H+] [A-]        OR        Ka = [product]           [HA]                                [reactant]pKa = -log KaHenderson-Hasselbalch Equation:pH = pKa + log [A-]        OR         pH = pKa + log [proton acceptor]                         [HA]                                      [proton donor]***if [A-] = [HA], then pH = pKa (b/c log (1) = 0)***Functional Groups[pic 1]Oxidation/Reduction ReactionsOIL RIG – “Oxidation is loss of electrons; Reduction is gain of electrons”                        (or addition of oxygen)                   (or removal of oxygen) 1o alcohols are oxidized to aldehydes2o alcohols are oxidized to ketonesAldehydes are oxidized to carboxylic acidsCarboxylic acids are reduced to aldehydesAldehydes/ketones are reduced to 1o/2o alcohols, respectivelyOther important chemical reactionsAcid + Alcohol = Ester                    Acid + Sulfhydryl group = ThioesterAcid + Amine = AmidePhosphoric Acid + Alcohol = PhosphoesterAMINO ACIDSGeneral Structurezwitterionic (dipolar) form predominates at a neutral pH[amino group carries slight (+) charge][carboxyl group carries slight (-) charge]can act as eitheran acid (proton donor)  and have negative chargeORa base (proton acceptor) and have a positive chargeAMPHOTERIC: both acidic and basicstandard amino acid has no net charge at pH=7 (if side chain R not polar)if R = acidic, net charge > 0if R = basic, net charge <0isoelectric pH (pI) – pH of a specific amino acid in which its net charge = 0if the charge of an amino acid is changed, the molecule can be activated or inactivated[pic 2]Main components:α-Carbon (chiral – central Carbon atom is bonded to four different groups)1o amino groupcarboxyl groupvariable side chain (R)StereoisomerismLevorotatory (L-) rotate light to the leftDextrorotatory (D-) rotate light to the rightOnly L-amino acids are used to make proteins in the human systemClassificationdifferent chemical properties of amino acids are due to the presence of difference side chains or R-groupsthey can be:polarnonpolararomaticpositively charged (acidic)negatively charged (basic)both the amino and the carboxyl groups can ionizecarboxyl group donates H+ more readily than the amino groupR-groups of some amino acids can ionizeNonpolar, aliphatic R groups (neutral) - VPGMAIL*glycine is the simplest amino acid; does not have a chiral center[pic 3]*One H-atom of glycine is replaced by methyl group (CH3) to make alanine*valine, leucine, and isoleucine are branched chain amino acids[pic 4]                Polar, Uncharged R-Groups GCAST[pic 5]*serine, threonine, and tyrosine contain a hydroxyl (OH-) group as their side chain ~ important for attachment of phosphate group in cellular signaling