Biochemistry I Spring/Summer 2024 Lecture Notes PDF

Biochemistry I Spring/Summer 2024 Lecture 2 March 5, 2024 Textbooks: Mark’s Basic Medical Biochemistry 5th Edition And Harper’s Illustrated Biochemistry 30th Edition Exam 1 Tuesday March 26 covering lectures 1-4, homework, reading Review: be able to calcul...

Biochemistry I Spring/Summer 2024 Lecture 2 March 5, 2024 Textbooks: Mark’s Basic Medical Biochemistry 5th Edition And Harper’s Illustrated Biochemistry 30th Edition Exam 1 Tuesday March 26 covering lectures 1-4, homework, reading Review: be able to calculate a molecular formula and calculate molecular weight. For example: Ibuprofen The S form is the more pharmacologically active form and the R form has no anti-inflammatory effect. Molecular formula: C13H18O2 molecular weight = 206.14 g mol-1 Atomic number Atomic weight Mass number Isotopes (C, H, O) Covalent vs Ionic Bonds Electronegativity  Chapter 4 acids, bases, and buffers Water: Dipolar molecule Metabolism Maintnance of pH generates CO2 Forms hydrogen bonds Lactic acid Solvent Ketone bodies Pyruvic acid Pure water pH = 7.0 Amino acids respiratory Water dissociates to A physiological proton and hydroxide pH = 7.4 is maintained- Acid- releases H+ Base- accepts H+ deviations are buffers life threatening Strong acid/strong base Weak acid/weak base Carbonic acid Bicarbonate Dissociation constant Ka phosphate Henderson-Hasselbalch hemoglobin kidney equation Buffer: mixture of weak acid and conjugate base Buffer is effective at pH = pKa ± 1  Water forms hydrogen bonds with itself and other molecules containing polar covalent bonds (amines, alcohols, ketones, etc) Hydrogen bond 1 picosecond 10-12 s lifetime Hydration shells H2O 1 nanosecond NaCl → Na+ + Cl- 10-9 s lifetime Also, HCO3-, K+, PO3-, SO42- Major electrolytes: see table 4.1 ATP Bicarbonate and inorganic anions/cations ECF: HCO3-, Na+ and Cl- ICF: HPO42-. K+ From table 4.1 Na+ ECF 145 mmol/L ICF 12 mmol/L 1000 mmol = 1 mol 145 mmol = 0.145 M Physiological [H+] = 10-7.4 M 3.98 × 10-8 M 3.6 million time more sodium than proton Physiological [H+] = 10-7.4 M 3.98 × 10-8 M 0.145 M 3.6 million times more sodium than proton 0.145 M/3.98 × 10-8 M ≈ 3.6 million Why is pH = 7.4 maintained? One primary reason is enzyme activity Temperature increase and/or pH < 7.4 or pH > 7.4  pH = -log [H+] Strong Acids 100% Dissociated 0.01 M 𝐻+ [𝐶𝑙−] Ka = [𝐻𝐶𝑙] Cl- is the conjugate base and the conjugate base of the strong strong acid HCl and is Exceedingly weak! HCl does not reform! Example pH of a 0.01 M solution of HCl in water is pH = -log (0.01) = 2, pOH = 12, so [OH-] = 10-12 Likewise, strong bases dissociate 100% in water and Kb is large. Kb>>1. The conjugate acid of a strong base is Exceeding weak! 𝑁𝑎+ [𝑂𝐻−] Kb = [𝑁𝑎𝑂𝐻] What’s the pH of a 0.01 M solution of NaOH? pH = 12 Weak acids and weak bases (most acids and bases in biochemistry are weak!) Weak acids and weak bases dissociate [OH-] acidic