proteins Flashcards
what is the monomer of a protein?
an amino acid
how are proteins linked to DNA?
order of bases=amino acid order=protein which coded for a characteristic
what is the general structure of an amino acid?
R
H—- | ===O
N–C–C
H—- | —–OH
H
how many naturally occurring amino acids are there? give examples
20 eg. serine, glutamine, leucine
each with a different R group
what do 2 amino acids join together?
condensation reaction forms peptide bond, molecule of water produced
-OH and H removed
what is the primary structure of an amino acid?
-the specific order of amino acids in a polypeptide
-determined by DNA sequence of gene
bonds in primary structure
covalent bonds
what is the secondary structure?
-polypeptide sections twist and fold into shapes
-alpha helix and beta pleated sheet (flat)
bonds in secondary structure
hydrogen bonds form along polypeptide chain, due to attracting O and H charges
what is the tertiary structure?
-overall 3D shape of the polypeptide chain
-critical for how protein functions
bonds in tertiary structure
hydrogen bonds, ionic bonds, disulfide bonds, non polar hydrophobic interactions
what is the quaternary structure?
-shows how the individual sub units (polypeptide chains) are arranged to form a larger 3D structure
-shows position of any prosthetic groups
bonds in quaternary structure
hydrogen, van der Waals, forces between non polar side chains
what is a prosthetic group?
when proteins are accompanied by non protein molecules which make up the structure and help to carry out the role
what is a conjugated protein?
a globular protein with a non protein element called the ‘prosthetic group’
what is a globular protein+ examples
spherical soluble protein
eg. haemoglobin, insulin, enzyme
structure of haemoglobin
-quartnenary protein with 4 polypeptides-2 alpha helix, 2 beta pleated sheet
-prosthetic ‘haem’ group
function of haemoglobin
-transports oxygen
-‘haem’ group binds irreversibly to oxygen
structure of insulin
-spherical, compact, soluble
-complex shape, folds into tertiary shape
-has precise shape for receptors
function of insulin
-hormone that regulates blood glucose concentration
enzyme structure
-quartnernary protein
-contains 4 ‘haem’ prosthetic groups
enzyme function
-catalyses reaction
-interacts with hydrogen peroxide to speed up its breakdown
fibrous proteins meaning and examples
insoluble and strong proteins with structural role for support/protection
-collagen, keratin, elastin
collagen function
-connective tissue in skin, tendons, ligaments and nervous system
