4: Buffers, Polyprotic acids; Amphoteric Substances,
- Page ID
- 6094
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)
Reading & Problems: LNC p. 63-66, p. 72 prob. 12, 15-18, 20-29; Segel p. 92 prob. 25 a,d,f (note: pKa for ammonia is 9.26), 32, 34, 38a (here is the 
solution to 38a, but see if you can do it yourself first!), p. 93 prob. 40, 42 (if additional clarification is needed, read Segel p. 31- 41, 53-62)
I. Buffers - mixtures of conjugate acid and conjugate base at ±1 pH unit from pH = pKa. Resistant to changes in pH in response to small additions of H+ or OH-.
II. Polyprotic acids - dissociation of each H+ can be treated separately if the pKa values are different.
IV. Introduction to proteins - linear chains of amino acids connected by peptide bonds.
- Enzymes - protein catalysts, facilitate/enable most of the reactions in a cell.
- Binding - receptors mediate communication, O2 storage and transport (myoglobin, hemoglobin), antibodies for defense.
- Channels/pumps - proteins embed in cell membranes allow selective flow or transport of small molecules.
- Structure - collagen in connective tissue of animals, extensin in plant cell walls.
- Movement - dynamic assembly of cytoskeleton (actin filaments, microtubules), motor proteins provide directional movement of cells and subcellular components.
V. alpha amino acids - 20 different ones are used in protein synthesis. The properties page also links to 3-D structure views.
Contributors
Charles S. Gasser (Department of Molecular & Cellular Biology; UC Davis)