PROTEINS Flashcards
What are the different levels of proteins?
Monomer - amino acids
Dimer - dipeptide
Polymer - polypeptide
Proteins are made from 1 or more polypeptides
What is the structure of an amino acid?
An amino group, and a carboxyl group, along with a hydrogen atom are connected to a carbon atom.
Alongside that, is a carbon containing R group
There are 20 differenet amino acids in all living things
How do (di/poly)peptides form?
A condensation reaction occurs.
This is between one of the hydrogen atoms on the 2nd amino acid’s amine group, and the oxygen + hydrogen atoms on the 1st amino acid’s carboxyl group
A peptide bond is formed between the carbon and nitrogen atoms across the peptide bonds, while a water molecule is produced
What is the test for proteins?
Add the test solution to a test tube, and add an equal volume of sodium hydroxide solution, as the solution needs to be alkaline
Also, add some copper (II) sulfate solution, and mix
The solution goes purple if peptide bonds are present
The NaOH/Cu(II)SO4 solution can be substituted by Biuret’s reagent
What is the pimary structure of a protein?
This is the chain of amino acids, the specific sequence in the polypeptide chain
What is the secondary structure in a protein?
Hydrogen bonds form between the amino acids. This causes the polypeptide chain to coil into an alpha helix, a complex 3D shape
What is the tertiary structure in a protein?
The alpha helixes fold and twist to produce more complex structures, with these structures being maintained by different types of bonds, depending on the protein’s primary structure:
disulfide - fairly strong, not borken easily
ionic - weaker than disulfide bonds, easily broken by pH changes
hydrogen - large in number but weak
What is the quartenary structure in proteins?
Larger proteins contain many individual polypeptide chains, and can be linked in various ways.
Also, non-protein groups (prosthetic) can be associated with the molecule.
