FOUNDATION-enzymes

Question 1

what is an enzyme?

Answer 1

• proteins that help speed up metabolism (the chemical reactions in the body)
• reduce activation energy-minimum energy required for reaction to take place

Question 2

how does temperature affect enzymes?

Answer 2

• as temp increases so does kinetic energy of molecules increasing rate of ESC formed
• any temp above optimum causes damage to active site and thus denaturation of enzyme

Question 3

what is the optimum temperature for enzymes?

Answer 3

37 degrees Celsius

Question 4

how does pH affect enzyme acitivity?

Answer 4

• optimum pH varies depending on where enzyme is in body (eg pepsin works in stomach- high HCl pH=1-2)
• non optimal pH leads to denaturation-different conc on H+ ions alters tertiary structure of active site

Question 5

what is the affect of increased substrate concentration on enzyme activity?

Answer 5

• increase in substrate concentration=increase in enzyme activity
• up until the a point where all active sites are used up=Vmax

Question 6

what is non-competitive inhibition?

Answer 6

• inhibitor competes with substrate to bind to enzymes active site (has same complementary active site)
• prevents substrate from binding

Question 7

how do you lessen the affect of competitive inhibition?

Answer 7

increase substrate concentration

Question 8

what is non-competitive inhibition?

Answer 8

• substance binds to allosteric site on enzyme

- changes shape (conformational change) of binding site so substrate can no longer bind (no longer complementary shape)

Question 9

which type of inhibition is reversible and which is irreversible?

Answer 9

• reversible- competitive inhibition (ionic forces)

- irreversible - non-competitive (covalent forces)

Question 10

what is negative feedback inhibition?

Answer 10

• end product binds to enzyme at start of pathway
• stops metabolic pathway and stops more products being produced

-eg glucose-6-phosphate inhibits hexokinase to decrease the rate of glycolysis

Question 11

The active site of an enzyme differs from an antibody-antigen binding site in that the enzyme active site

a. Contains modified amino acids
b. Catalyses a chemical reaction
c. Is complementary to specific ligand
d. Contains amino acids without side chains

Answer 11

b