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Practical

Terms in this set (13)

pH
hydrogen ion concentration

pH = -log[H+]

based on moles per liter and a logarithmic scale
Ka
acid dissociation constant

Ka = [H+][A]/[HA]

the more hydrogen ions released when a given amount of acid is dissolved in water, the larger the Ka and the stronger the acid
pKa
numerical measure of the acid strength of a buffer

pKa = -logKa
Henderson-Hasselbalch equation
pH = pKa + log [A-]/[HA]

when the concentration of a weak acid = concentration of the conjugate base, pH = pKa (max buffering capacity)
Buffer problem equation
C1V1 = C2V2
general amino acid structure
Amino group, carboxyl group, and R-group bonded to the same carbon (alpha carbon)
R group
a functional group that defines a particular amino acid and gives it special properties

varies in structure, size, and charge
5 main amino acid classes
1. Nonpolar, aliphatic R groups
2. Aromatic R groups
3. Polar, uncharged R groups
4. Positively charged R groups
5. Negatively charged R groups
1. Nonpolar, aliphatic R groups
Hydrophobic

Glycine
Alanine
Proline
Valine
Leucine
Isoleucine
Methionine
Glycine (small side chain of H atom doesn't make big contribution to hydrophobic interaction, but its in this group bc lack of polar side chain
2. Aromatic R groups
Nonpolar + hydrophobic due to aromatic side chain

Phenylalanine
Tyrosine (+ can participate in H bonding via hydroxyl group)
Tryptophan
3. Polar, uncharged R groups
More water soluble than groups 1 + 2

Serine (polar hydroxyl group)
Threonine (polar hydroxyl group)
Cysteine (polar sulfhydryl group)
Asparagine (polar amide group)
Glutamine (polar amide group)
4. Positively charged R groups
Lysine
Histidine
Arginine
5. Negatively charged R groups
Aspartate
Glutamate

both have carboxyl group
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