3.1.4.1 Flashcards
Which monomer makes up proteins?
Amino acids
What is the general structure of an amino acid?
R
|
H2N ——– C ——- COOH
|
H
Label each group in an amino acid.
NH2 = amine group
COOH = carboxyl group
R = variable group
How many amino acids are there?
20
How are the 20 amino acids different?
Their ‘r’ group / side chain
How is a peptide bond formed?
A condensation reaction between two amino acids
How is a dipeptide formed?
By the condensation of two amino acids
How are polypeptides formed?
By the condensation of many amino acids
How are peptide bonds broken?
Hydrolysis by proteases
Describe the primary structure of a protein
Sequence of amino acids in the polypeptide chain joined by peptide bonds through condensation reactions
Order determined by genetic code
Position of amino acid determines the bonds formed between the amino acids to produce further levels of structure
Describe the secondary structure of a protein
The shape the primary structure folds or coils into
Alpha helix- spiral held by hydrogen bonds
Beta pleated sheet- polypeptide chains form layers with hydrogen bonds between them
Describe the tertiary structure of a protein
Further folding or coiling of the secondary structure to form a globular or fibrous molecule
Gives characteristic shape closely related to its function
Held by hydrogen bonds, ionic bonds, disulphide bridges or hydrophobic interactions
Describe the quaternary structure of a protein
When more than one polypeptide chain is involved in a protein.
Describe the test used for proteins
Add biuret reagent (equal amounts of copper sulphate and sodium hydroxide)
If protein present will turn from blue to purple
