Proteins Flashcards
What are proteins made up of ?
-Amino group
- carboxyl group
- variable group
- hydrogen
-central carbon
How do amino acids join to form a dipeptide?
- condensation reaction
-Water removed
-Peptide bond forms between OH of carboxyl and H or amine groups
What are proteins?
Polymers made up of amino acids(20 diff aa’s)
Primary structure of a protein.
The order of AAs in a polypeptide chain. Peptide bonds hold AAs together
Secondary structure of a protein.
1) The sequence of amino acids causes parts of a protein molecule to bend into alpha helix shape or fold into beta pleated sheets.
2) structure held in place by hydrogen bonds. These form between C-O groups of the carboxyl of an AA and the H in the amine group in another. Several form which provides strength
Tertiary structure of proteins.
The secondary structure gets further folded
To form a unique 3-D shape
Held in placed by ionic , hydrogen and disulphide bonds
Ionic and disulphide bonds form between the R groups of diff AAs
Disulphide only occur if AAs have a sulphur in their R groups
Quaternary structure of proteins
A protein made of more than 1 polypeptide
Eg haemoglobin is made of 4!
What does it mean for protein is denatured?
Bonds which hold the tertiary and secondary structure in shape break and therefore the unique 3-D shape is lost
Collapses back to secondary structure
Eg enzymes lose their unique active site shape
Conditions that denature proteins
Too high temperature(too much kinetic energy)
Too high /low pH( too many H+ or OH-)
Importance of primary structure
Exact sequence of AAs is what determines where the bonds form
This results in a diff 3D shape
Impact: enzymes will have a different shaped active site.( non functioning)
Carrier proteins have a diff binding site so no longer complementary
What causes a change in AA Sequence
Mutations; change in DNA , might then code for a diff aa leading to the primary structure changing
