Protein Structure And Function Flashcards
What are proteins made up of?
Polypeptide chains made up of amino acids
What are the 4 main groups of an amino acid?
An amino group, a carboxyl group, a hydrogen atom and a side chain.
What is an amino acid called when it has been joined by a peptide bond to make a protein?
An amino acid residue
Name 3 basic amino acids and 2 acidic.
Basic - Lysine, Arginine, Histidine
Acidic - Aspartate and Glutamate
Which groups lies at the N terminal of a protein and which at the C terminal?
N - Amino group
C - carboxyl group
What is the basic principle regarding whether the ph of a solution is smaller / bigger that the pk of an amino group?
If an amino acid is BASIC then it is PROTONATED, if the ph of a solution is smaller than the pk value of the aa, it is positively charged. This is because the solution is forced to the right, so there are more H+ions.
If an amino acid is ACIDIC then it will be DEPROTONATED - negatively charged. the opposite of what you think it is.
Explain the four different sized structure of proteins.
Primary - amino acids arranged like beads on a string.
Secondary - a polypeptide backbone, an alpha helix structure.
Tertiary - 3D configuration of the alpha helix, starts to move a unique structure affecting its function.
Quarternary - A multiple peptide sub-unit - the largest
Where are peptide bonds formed? And what is produced in the process?
Formed between the N and C terminals, between the amino group of one aa and carboxyl group of the next. An H20 molecule is produced.
Describe 3 characteristics of peptide bonds.
PLANAR - all lie in the same plane
RIGID - They have partial double bond characteristics which make them less flexible.
TRANS CONFIRMATION - This means the bonds form on opposite sides.
What type of bonds stabilise the alpha helix structure?
Hydrogen bonds
What amino acid is a helix breaker and why?
PROLINE - Makes rotation impossible, stops formation.
What is it could when lots of alpha helixes are put together?
A Beta sheet
Name the two tertiary structures for a group of proteins and give an example of each.
Fibrous e.g. Collagen - 3 alpha helixes wrapped together.
Globular - a big bundle e/g/ myoglobin.
How would you know an amino acid is neutral? Example?
No negative or positive charges on the side chain. E.g. Serine, cysteine.
How would you know if an amino acid is acidic? Example?
There would be a negative charge e.g. A COO- group e.g Aspartic acid
