Amino Acids and Proteins Flashcards
What are the biological roles of proteins?
Transport, storage, enzyme catalysts, motion, skeletal support, immune protection, nerve impulse transmission, control of metabolism
What does a protein consist of?
either single or several polypeptide chains
what is an unbranched polypeptide chain?
polymer of amino acids linked by a peptide bond
what is the smallest functional protein?
tripeptide called thyrotropin-releasing hormone
how many amino acids are there?
20
what are the side chains on the amino acids?
acidic COOH, basic NH2, H and R
where do L-amino acids occur?
proteins
where do D-amino acids occur?
bacterial cell walls
what is electronegativity
the power of an atom to attract electrons towards itself
What makes R groups polar?
presence at pH 7 of full +ve or -ve charge in R group or partial charges in permanent dipole bonds in non-ionisable R groups
What makes R groups nonpolar ?
many nonpolar C-C and C-H bonds
Give an example of a nonpolar amino acid
alanine
Give an example of a polar amino acid
lysine
what does hydroxyproline do?
the OH group stabilises collagen fibre
what does Y-carboxyglutamate do?
carboxylation of Glu in prothromnin
