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
what does O-phospherine do?
phosphorlyation of serine is the most common form of regulation of protein activity
what is primary structure?
amino acid sequence
what is secondary structure?
arrangement in space of amino acids close to one another in a polypeptide chain
what is tertiary structure?
3D structure of all the atoms in a single polypeptide chain. interactions between R groups fold protein into a compact 3D shape
what is quaternary structure?
3D interaction of protein subunits in proteins with more than one polypeptide chain
