Biological Molecules 2

Amino acid

NH2- amine group

COOH- carboxyl group

variable R group

Peptide bond

Condensation between two amino acid

Dipeptides

Condensation of two amino acid

Polypeptides

Condensation of many amino acid

Protein

polymer of amino acid

Primary structure

initial sequence of amino acid

Secondary structure

hydrogen bonds form between chain leading to shape like alpha helix or beta pleated sheet

Tertiary structure

3D shape of protein from by further twisting and folding

Disulfide bridge

covalent bond between sulphur in cystene R group

Ionic bond

form between carboxyl and amino group that doesn’t involve peptide bond

Quaternary structure

several different polypeptide chain held together by bonds as the protein’s final 3D sturcture

Biuret test for protein

Add NaOH and CuSO4

Colour change from blue to purple

Enzyme

lowers activation energy of reacton when catalysts

Induced-fit model

the shape of the active site change slightly when enzyme binds with complementary substrates to form enzyme-substrate complex

Temperature

rate of reaction increase up to optimum temperature

rate of reaction decrease above the optimum temperature as the enzyme becomes denatured

pH

rate of reaction increase in optimum pH

OH ions distrupt bonds that hold enzyme’s tertiary structure, affecting the shape of active site

enzyme concentraton

rate of reaction increases as there are more active site for substrate to bind to

substrate concentraton is a limiting factor

substrate concentration

rate of reaction increases as there is a higher chance for collision

enzyme concentraton is a limiting factor

competitive inhibitor

compete with substrate to bind to the active site to block entry of substrate

non-competitive inhibitor

alternate the shape of the active site so substrate can no longer fit into active site