Proteins Flashcards
what is the primary structure?
An exact sequence of amino acids in a polypeptide chain
what bonds are in the primary structure?
Peptide bonds- between the amine group and carboxyl of another
what reactions forms a peptide bond?
Condensation
what is the secondary structure?
Polypeptide chain folds into- Alpha helix’s and Beta pleated sheets
what bonds are in the secondary structure?
Hydrogen bonds- between hydrogen and oxygen (causes the coils and sheets)
what is the tertiary structure?
Further folding of the secondary into a 3D shape. Affected by R groups
what are the intermolecular bonds in the tertiary structure?
Ionic- between charged R groups
Hydrophobic- between NON polar R groups
Hydrophillic- between polar R groups
Disulfide bridges- between 2 sulfur atoms
what is the quaternary structure?
more than one polypeptide chain bonded with any bonds from the tertiary structure
what is a fibrous protein?
long, thin, strong, un reactive and INSOLUBLE structures
examples of fibrous-
Collagen, Elastin, Keratin
Collagen
Found in connective tissues- skin, muscles
Minerals bind to the protein- increasing rigidity
Elastin
Found in elastic connective tissue- large blood vessels
Allows tissues to adapt their shape
Keratin
Found in external structures- hair, nails
Either flexible or tough (rich in cysteine)
Provides impermeable barrier
what is a globular protein?
round, compact, SOLUBLE with hydrophobic and hydrophilic R groups
examples of globular-
Haemoglobin, Insulin, Pepsin
Haemoglobin
4 polypeptide chains with 4 prosthetic groups (haem) which includes Fe2+ and binds to oxygen
Insulin
2 polypeptide chains (alpha and beta) joined by sulphide bonds
Regulates blood glucose levels.
Pepsin
Single polypeptide chain of 327 amino acids
Breaks down proteins in the stomach
what is a conjugated protein?
protein with a non- protein attached to it (haemoglobin) joined by COVALENT (WEAK interactions)
what is a prosthetic group?
a non protein group
general structure of amino acid
R
|
H2-N--C--COOH
|
H
