Protein structure Flashcards
What are proteins made up of?
Amino acids
What are two amino acid held together by?
A peptide bond
What is the primary structure of a protein?
The order of amino acids
What is the secondary structure of amino acids?
- localised folding of polypeptide chains e.g. Alpha helix and Beta pleated sheet
- held together by hydrogen bonds which form between the H of the amine group and and the O of the carboxyl acid
Draw a amino acid and label it.
hd
What is the quaternary structure?
- only some proteins have a quaternary structure
* it mean they are made of more than 1 polypeptide chain
What is the tertiary structure?
- how the secondary structure is folded into a specific 3d shape
- different for each protein
What are used to determine the shape of a protein and why?
R groups are used to determine the shape.
• polar R groups are hydrophilic so move towards the edge of the protein
• non-polar R groups are hydrophobic and move towards the centre of the protein
How are polypeptide chains held together?
- hydrogen bonds
- Ionic bonds - attraction between + and - charges
- Disulphide bonds: whenever 2 molecules of amino acid cysteine come close together the sulphur atoms bond
Name a globular protein
Haemoglobin
Name a Fibrous protein.
Collagen
Describe Globular proteins.
- Roughly spherical
- Made up of 4 polypeptide chains
- soluble due to hydrophilic side chains on the outside and the hydrophobic R groups being contain within: useful to move around in liquid
- contains 4 haem groups that bind to oxygen
Describe Fibrous proteins.
- A long thin protein
- Insoluble
- Very strong
- structural
- Made up of 3 polypeptide chains that are coiled into alpha helixes that wound round each other
Describe how a polypeptide is formed.
More than 2 amino acids join together in a chain via condensation reaction reaction. Each reaction forms a peptide bond and releases a molecule of water.
