Proteins and Enzymes

Question 1

What is a protein?

Answer 1

A polymer built up of one or more amino acids

Question 2

What is significant about an amino acids R group?

Answer 2

The R group is different in all amino acids

Question 3

What groups does an amino acid contain?

Answer 3

• An amine group- A carboxylic acid group- A r group- A hydrogen

Question 4

What is the bond called that forms between amino acids?

Answer 4

A peptide bond

Question 5

What reaction forms a dipeptide?

Answer 5

A condensation reaction

Question 6

What is a dipeptide?

Answer 6

Two amino acids joined by a peptide bond

Question 7

What is the primary structure of a protein?

Answer 7

The sequence of amino acids

Question 8

What is the secondary structure of a protein?

Answer 8

Coiling and folding of the polypeptide chain. A helixes and Beta pleated sheets

Question 9

What is a proteins tertiary structure?

Answer 9

Its final 3D shape, Extensive Coiling and folding of the polypeptide chain with Peptide bonds(primary), hydrogen bonds(secondary) and ionic bonds and disulphide bridges

Question 10

What is a proteins quaternary structure?

Answer 10

A protein made from multiple polypeptide chains

Question 11

What is the test for proteins called?

Answer 11

The biuret test

Question 12

How do you carry out the test for proteins?

Answer 12

Add the biuret reagent (Copper Sulphate), purple indicates protein present

Question 13

How do you answer a protein shape question?

Answer 13

The tertiary structure of the active/binding site is complimentary to the shape of the substrate and can form an enzyme-substrate complex/an antibody-antigen complex

Question 14

How do you answer a non-functional protein question? (mutation)

Answer 14

A change in the proteins primary structure causes changes in the proteins tertiary structure which changes the shape of the active site therefore the substate is no longer complimentary and cannot form an enzyme-substrate complex

Question 15

Why does the rate of enzyme catalysed reactions increase up to the optimum temperature?

Answer 15

As temperature increases molecules vibrate more therefore more collisions will take place with a higher percentage being successful and colliding with the activation energy therefore more enzyme - substrate complexes are formed

Question 16

What happens to enzymes as the pH increases/decreases away from the optimum?

Answer 16

enzyme rate of reaction decreases as the increase/decrease in OH- or H+ ions interact with the hydrogen and ionic bonds causing the tertiary structure to change and the active site will no longer be complimentary to the substrate and an enzyme-substrate complex won’t be able to form

Question 17

Why does rate of reaction increase as enzyme concentration increases?

Answer 17

more successful enzyme-substrate collisions will take place at a quicker rate therefore more enzyme-substrate complexes will form

Question 18

Why does rate of reaction increase as substrate concentration increases?

Answer 18

more successful enzyme-substrate collisions will take place at a quicker rate therefore more enzyme-substrate complexes will form

Question 19

How do competitive inhibitors work?

Answer 19

They have a similar shape to the substrate and can bind to the active site, preventing enzyme-substrate complexes from forming

Question 20

How do non-competitive inhibitors work?

Answer 20

They bind to the enzyme at an alternative location to the active site which changes the shape of the active site so that enzyme-substrate complexes can no longer form