enzymes

Question 1

enzyme + substrate =

Answer 1

enzyme substrate complex (ESC)

Question 2

As temperature moves away from the optimum, why does the rate of reaction decrease?

Answer 2

• temp too low: there is a reduction in energy available for the reaction
• temp too high: the bonds holding the enzyme in a specific 3D shape have been broken (denatured). The shape of the active site is altered so that the substrate no longer fits into the active site

Question 3

enzyme optimum pHs

Answer 3

• a functional enzyme in the stomach will have an optimum pH of around pH 2
• a functional enzyme in the small intestine will have an optimum pH of around pH 8

Question 4

As pH moves away from the optimum, why does the rate of reaction decrease?

Answer 4

-in either direction, the enzyme begins to denature and the rate of reaction falls

Question 5

can enzyme activity be restored to normal when conditions are brought back to the optimum after being too high?

Answer 5

no, once denatured, the functional shape of the enzyme’s active site is destroyed and the enzyme can no longer catalyse the reaction.

Question 6

amylase

Answer 6

starch to maltose

Question 7

protease

Answer 7

protein to amino acids

Question 8

lipase

Answer 8

lipid (fat/oil) to glycerol and fatty acids

Question 9

intracellular enzymes

Answer 9

enzymes that work inside cells e.g. enzymes involved in respiration or photosynthesis

Question 10

extracellular enzymes

Answer 10

enzymes that work outside cells e.g. digestive enzymes

Question 11

digestive enzymes

Answer 11

• produced by specialised cells in glands and tissues, e.g. salivary glands, stomach lining, pancreas, intestinal lining.
• secreted from the cells, e.g. into the mouth, stomach or small intestine, where they come into contact with the food molecules

Question 12

commercial uses of enzymes

Answer 12

• biological washing powders to digest food stains
• production of sugar syrups
• manufacturing pharmaceuticals
• making ethanol from plants
• wine and beer production.

Question 13

Why are the digestive enzymes of a human extracellular?

Answer 13

the food molecules are too big to cross the membrane into the cells for digestion so enzymes need to be secreted into the gut to digest these molecules, allowing their products to be absorbed and used by cells

Question 14

treating an enzyme with another enzyme

Answer 14

-breaks the bonds between the amino acids in the enzyme, altering its specific shape and resulting in loss of function

Question 15

pH change effect

Answer 15

• the pH scale is logarithmic so even a change of 1 or 0.5 can be devastating to enzyme activity
• pH change causes changes in electric charge on proteins that could interfere with protein-protein interactions