Proteins + Amino Acids

what is a protein?

large molecules made up of chains of amino acids

what is a dipeptide?

2 amino acids covalently joined by a peptide bond

what is a peptide bond?

covent bond formed between 2 amino acids

what is the primary structure of a protein?

order of amino acids in a polypeptide chain which are formed by peptide bond via condensation reaction

what is the secondary protein structure?

initial folding of polypeptide chain due to formation of hydrogen bonds into 2 3D shapes: a-helix, b-pleated sheet

describe structure of a-helix

polypeptide chain forms spiral

each amino acids forms hydrogen bonds with the amino acid 4 units along

describe the structure of b-pleated sheet

2 parts of the polypeptide chain lay side by sid, hydrogen bond formed between them

what are the 4 types of bond in a tertiary structure that can form between R groups of amino acids?

hydrogen bonds

disulfide bridge

hydrophobic interactions

ionic bond

what is quaternary structure of protein?

final 3D shape formed from more than one polypeptide chain

what are features of the globular structure?

spherical shape

water soluble due to hydrophilic R groups forming hydrogen bonds

may be conjugated

function depends on shape

easily denatures

what is a prosthetic group?

molecule/ion tightly bound to protein or enzyme required for for biological function

non-amino acid, non-protein

which bonds are found in primary structure?

none

which bonds are found in secondary structure?

hydrogen bonds

which structure is the final 3D folded shape?

tertiary structure

which bonds are found in quaternary structure?

hydrogen bond

disulfide bridge

ionic bonds

homophobic interactions

what are features of globular proteins?

elastin

recoil, does not have high tensile strength

what are features of fibrous proteins?

straight chain linear unbranched

insoluble

high tensile strength

why are fibrous proteins insoluble?

no OH groups to form hydrogen bonds

what are the differences between globular and fibrous proteins

globular - spherical, soluble, highly folded, no structural function

fibrous - linear straight chain, insoluble, have structural function

what are the similarities between fibrous proteins and globular proteins?

which bonds does heating proteins break

hydrogen bonds

which bonds do strong alkalis and acids break

hydrogen bonds and ionic bonds

what is denaturating?

irreversible disruption of protein structure by breaking bonds