proteins

what groups are found on an amino acid

amine group, carboxyl group, r group

what bonds are found between amino acids

peptide bonds

what elements to proteins contain

C,H,O,N,S

what enzyme catalyses polypeptide formation

peptidyl transferase

what is the first level of protein structure and what occurs

primary - the sequence in which amino acids are joined, peptide bonds

what is the second level of protein structure and what occurs

secondary: initial coiling

- alpha helix: hydrogen bonding

- beta pleated sheet: hydrogen bonding

what is the third level of protein structure and what occurs

tertiary - 3d structure, further folding and coiling, hydrophilic and hydrophobic interactions, hydrogen bonds, ionic bonds, covalent bonds (disulphide bridges) between r groups with sulfur atoms

which amino acid forms disulphide bridges

cystine

what is the fourth level of protein structure and what occurs

quaternary - different subunits join up to form one big protein, same interactions as tertiary

what is an example of a quaternary protein

haemoglobin - 4 subunits, heam groups containing iron

what are the three types of protein

globular, conjugated, fibrous

what is the structure of globular proteins

spherical, soluble in water eg insulin

what is the structure of conjugated proteins

globular with a prosthetic group eg haemoglobin, group attached by covalent bond

what is the structure of a fibrous protein

strands, insoluble in water, structural support eg collagen- connective tissue, keratin- hair, skin, nails elastin- walls of blood vessels

collagen

main component of connective tissue, made of 3 polypeptide chains, insoluble, high tensile strength but flexible, found in arteries tendons bones cartilage

elastin

found in body parts that need stretching eg skin alveoli arteries

keratin

impermeable waterproof and good protection against pathogens, acts as barrier in hair nails, multiple cysteine residues

what enzymes are used to hydrolysis proteins

endopeptidase, dipeptidase and polypeptidase

what’s the difference between endopeptidase and exopeptidase

endopeptidase hydrolyse internal bongs

exopeptidase hydrolyse bonds at the end of protein molecules