7 - Polymers of Life (PL) Flashcards
(17 cards)
Properties of amino acids
-Have amine group and carboxylic acid group on the same carbon
-20 naturally occuring
-Bifunctional compounds
Formula for amine group
NH2
Define bifunctional compound
Compound with 2 functional groups
Define zwitterion
Dipolar ionic form of an amino acid, which is formed by donating a proton from the carboxyl group to the amino group
Define isoelectric point
pH value where the amino acid exists as a zwitterion
When an amino acid is below the isoelectric point
-Proton accepted from acid
-Forms positive ion in acidic solution
When an amino acid is above the isoelectric point
-Proton donated to OH- ion
-Forms negative ion in alkaline solution
Properties of amino acids in aqueous solutions
-Mostly zwitterions
-Very soluble in water (effectively ionic) - unless extra functional group, then neutral
-Buffer solution
-Can exist in 3 different forms, pH dependent
Define buffer solution
Adding small amounts of acid/alkali causes little change to the pH
Properties of proteins
-Condensation polymers
-Made by joining amino acid monomers with a peptide link
-Amine and carboxyl groups react
Define dipeptide
2 amino acids joined together
Define polypeptide chain
Many amino acids joined together
Primary protein structure
Amino acid sequence in the protein
Secondary protein structure
Regular local sub-structures, due to hydrogen bonding between main-chain peptide
Tertiary protein structure
3D structure of a single protein molecule, due to non-specific hydrophobic interactions and held in place by tertiary interactions
Quaternary protein structure
3D structure of a multi-subunit protein and how these subunits fit together, held by tertiary interactions
Examples of tertiary interactions
-Salt bridges (ionic)
-Hydrogen bonds
-Tight packing of side chains
-Disulfide bonds (covalent bonds)
