the folding and joining of a polypeptide by weak chemical bonds that give a 3D complex shape.
3 of 17
what is meant by a qauternary structure?
A protein that consists of more than one polypeptide e.g. haemoglobin.
4 of 17
which 4 elements are present in every amino acid?
Nitrogen, Hydrogen, Oxygen and Carbon.
5 of 17
what is the formula of the amino group?
NH2
6 of 17
what is the formula of the Carboxyl group?
COOH
7 of 17
when the carboxyl group ionises in solution which 2 ions are formed?
COO- and H+
8 of 17
write an equation to show the formation of a dipeptide by condensation of alanine (R group is CH3) and glycine (R group H) both are amino acids.
NH2CHCH3COOH+NH2CH2COOH = NH2CHCH3CONHCH2COOH
9 of 17
describe the biuret test for proteins?
The substance is warmed with a biuret solution if protein is present the a lilac/mauve colour will develop.
10 of 17
suggest why the proteins in cell membranes are globular rather than fibrous?
globular proteins need to be the right size to fit in the cell membrane if they were fibrous they would be too long.
11 of 17
Is an enzyme a globular or a fibrous protein?
A globular protein.
12 of 17
describe the structure of fibrous proteins?
They are made up of many polypeptides that bind together to form long fibres, they are physically tough and are insoluble in water
13 of 17
describe the structure of globular proteins.
They consist of one molecule, they are spherical or global in shape, they are soluble in water, they are biochemical rather than structual and have complex tertiary and quaternary structures.
14 of 17
Name 2 types of fibrous proteins?
Keretin and collagen
15 of 17
In cartilage the collagen rods are arranged in many different directions suggest an advantage of this.
The tangle of collagen rods make it less likely that the cartilage will tear.
16 of 17
In the cornea collagen rods are stacked in neat piles. Suggest the advantage of this.
The stacking of the collagen rods prevent light being scattered in all directions and the cornea has to be transparent.
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