proteins

Question 1

the elements that are present in amino acids and proteins

Answer 1

Nitrogen, carbon, hydrogen, oxygen and some times sulfur

Question 2

example of a role of a protein

Answer 2

haemoglobin transports oxygen around in the blood

Question 3

what are the monomers which form proteins called

Answer 3

amino acids

Question 4

what does the ‘R’ represent in the display formula of an amino acid

Answer 4

a carbon containing side chain

Question 5

where do amino acids differ

Answer 5

in their side chain

Question 6

what bond forms between two amino acids in a condensation reaction

Answer 6

peptide bond

Question 7

other than the bond what forms by the condensation of two amino acids

Answer 7

a dipeptide

Question 8

what parts of the amino acids react during a condensation reaction to form a dipeptide

Answer 8

the OH/hydroxyl group from one amino acid reacts with the hydrogen from the amine group of another to form the water molecule.

Question 9

how are polypeptides formed

Answer 9

the condensation of many amino acids.

Question 10

what is at each end of a peptide chain.

Answer 10

an amine group at one end and a carboxyl group at the other end.

Question 11

four levels of organisation of proteins structure

Answer 11

primary, secondary,tertiary, Quaternary

Question 12

describe the primary structure of a protein.

Answer 12

the sequence of amino acids in a polypeptide chain.

Question 13

describe the secondary structure of a protein.

Answer 13

the folding of a polypeptide into an alpha helix or beta pleated sheet.

Question 14

how is the structure maintained in the secondary structure of proteins.

Answer 14

hydrogen bonds between between the NH group of one amino acid and the c=o group of another.

Question 15

describe the tertiary structure of a protein.

Answer 15

the further folding of the polypeptide chain into a specific 3D complex shape.

Question 16

what determines how the polypeptide is folded in the tertiary structure of a protein.

Answer 16

the R group and the shape is held together between the R groups in different amino acids.

Question 17

three types of bonds between the R groups

Answer 17

Hydrogen bonds
ionic bonds- from between oppositely charged R groups
Disulphide bridges - covalent bonds which form between sulphur containing side chains.

Question 18

Why is the tertiary structure so important

Answer 18

the shape it forms determines how it reacts with other molecules e.g. active sites in enzymes

Question 19

what is quaternary protein structure

Answer 19

the structure of proteins which contains two or more polypeptide chains joined together.

Question 20

what is the chemical test for the presence of proteins

Answer 20

the biuret test - add biuret solution to the sample.
if the protein is present there will be a colour change from blue to lilac . If not present there will be no colour change.