Lecture 6 – Proteins
Function:
- Some proteins are enzymes, antibodies (defense against foreign invaders
such as bacteria or viruses), transporters.
- Proteins have plenty of functions. Strong role in homeostasis.
Structure:
- Polymers (1 protein is many monomers [amino acid] joined together to
make a macromolecule)
- Amino acid
Peptide bonds:
- Bonds in proteins, monomers joined together.
- A peptide bond is a chemical bond formed between two molecules when the
carboxyl group of one molecule reacts with the amino group of the other
molecule, releasing a molecule of water (H2O).
- C-N peptide bond – cannot rotate giving proteins specific structures.
Polypeptide relationship:
- Proteins are a polypeptide and a polypeptide is lots of amino acids joined
together with lots of peptide bonds.
- Polypeptide is an unbranched sequence of monomers.
- Proteins have specific sequences, which gives specifc structure and function.
Structure:
, - 3D shape (Fold)
- Sequence gives structure gives function.
- Must be properly folded to have function
- 4 levels of structure:
1) Primary – linear sequence of amino acids.
2) Secondary – Is stabilised by hydrogen bonds between peptide bonds.
Localised. Two forms – alpha helix or beta sheets (parallel [same] or
anti-parallel [opposite]).
Function:
- Some proteins are enzymes, antibodies (defense against foreign invaders
such as bacteria or viruses), transporters.
- Proteins have plenty of functions. Strong role in homeostasis.
Structure:
- Polymers (1 protein is many monomers [amino acid] joined together to
make a macromolecule)
- Amino acid
Peptide bonds:
- Bonds in proteins, monomers joined together.
- A peptide bond is a chemical bond formed between two molecules when the
carboxyl group of one molecule reacts with the amino group of the other
molecule, releasing a molecule of water (H2O).
- C-N peptide bond – cannot rotate giving proteins specific structures.
Polypeptide relationship:
- Proteins are a polypeptide and a polypeptide is lots of amino acids joined
together with lots of peptide bonds.
- Polypeptide is an unbranched sequence of monomers.
- Proteins have specific sequences, which gives specifc structure and function.
Structure:
, - 3D shape (Fold)
- Sequence gives structure gives function.
- Must be properly folded to have function
- 4 levels of structure:
1) Primary – linear sequence of amino acids.
2) Secondary – Is stabilised by hydrogen bonds between peptide bonds.
Localised. Two forms – alpha helix or beta sheets (parallel [same] or
anti-parallel [opposite]).
