Proteins Flashcards
Name 7 types of Amino Acid
- Aliphatic
- Aromatic
- Uncharged Polar
- Other (Proline)
- Sulphur containing
- Acidic
- Basic
Explain an Aliphatic Amino Acid
R group is made up of straight or branched carbon chains
Explain an aromatic Amino Acid
R group contains Phenyl (benzene) groups
Explain an uncharged Polar Amino Acid
R group is uncharged but polar so has a localised charge making them capable of hydrogen bonding and hydrophilic
Explain Acidic Amino Acids
Contains COOH groups which can lose protons making them acidic
Explain Basic Amino Acids
Contain Nitrogen groups that resemble ammonia and can accept protons making them basic
Define Primary Protein Structure
The sequence of amino acid residues in a linear polypeptide chain
Define Secondary Protein Structure
The spatial arrangement of amino acid residues close to eachother in the linear polypeptide chain.
Name two structures created by arrangement of the secondary structure
The Alpha Helix and Beta Pleated sheets
What links amino acid residues in the secondary structure?
Hyrdogen Bonds
Define Tertiary Structure
The spatial arrangement of amino acid residues far apart in the linear polypeptide chain.
What forces hold the tertiary structure in place?
- Numerous, weak van der waals forces
- Hydrogen Bonds
- Rare but strong ionic interaction between oppositely charged ions
- Disulphide bridges, covalent bonds between sulphur ions in two cysteine residues
- Hydrophobic interactions, intra-polypeptide interactions which occur in an enviroment within proteins in which water is excluded. Cause the protein to coil up so the hydrophobic residues face inward and teh hydrophilic outward.
Define Quaternary Structure
The spatial arrangement of individual polypeptide chains in a multi-subunit protein
How does denaturation affect protein stucture?
It can disrupt or break bonds in the secondary and tertiary structures, changing the shape and function of the protein. However it is not strong enough to break peptide bonds so the primary structure is unaffected.
Name 6 causes of Denaturation
Heat Acid Solvents Crosslinking reagents (formaldehyde) Chaotropic agents (Urea) Disulphide bond reducers.
Name 4 effects of Denaturation
Improved Digestibility
Reduced water binding capability
Loss of biological activity
Decreased Solubility
Define a Glycoprotein
A compound composed of a protein and a carbohydrate. Glycosylation where a sugar molecule binds to an amino acid in the protein.
What are the 5 roles of Glycoproteins?
Protein Stabilisation Signalling Cell recognition Affects Solubility Protein Orientation
Define a metalloprotein
A protein molecule with a bound metal ion such as haemoglobin
Name 4 roles of metalloproteins
Transport
Enzymes
Signalling
Storage
Define a Lipoprotein
A protein bound covently or non-covently to lipids.
Whats the function of lipoproteins?
To transport not water soluble fats and cholestorol around the blood stream.
Define Co-operative binding
In a multi-subunit protein binding to one of the chains causes the shape of the others to alter making it easier for them to bind.
Name the 5 functions of globular Proteins
- Enzymes
- Hormones
- Transporters
- AMino acid stocks
- Structural
Name the 4 structural functions of fibrous proteins
Bone Matrices
Muscle Fibre
tendons
Connective Tissue
Compare the structures of Globular and Firbous proteins
Globular proteins are made up of interwoven polypeptide chains.
Fibrous proteins are made up of helixes formed from polypeptide chains wound round more helixes to form strong fibres and held together by H bonds.
Explain 4 Properties of Collagen
- Fibrous Protein
- Makes up 25% of our prtein
- High tensile Strength
- is made from a glycine-X-proline repeating unit
