4.2 Enzyme Activity (Inhibitors etc.)

Question 1

For enzymes to catalyse a reaction, what must happen

Answer 1

enzymes have to come into contact with the substrate, and the enzyme must be complementary shape to the substrate

Question 2

What factors affects enzyme activity

Answer 2

internal pH, temperature; these can cause changes in the shape of the active site.

Question 3

How can factors affecting enzyme action be investigated

Answer 3

by measuring the rate of reactions they catalyse

Question 4

How does temperature affect enzyme activity

Answer 4

The increased temperature causes more kinetic energy, which causes the particles to collide more often, increasing rate of reaction.

Question 5

What’s the temperature coefficient in a reaction

Answer 5

a measure of how much the rate of reaction increases with every 10 degree increase in temp.

Question 6

What causes enzymes to denature

Answer 6

The proteins that make up the enzymes are held together by bonds that vibrate; as the temp increases the vibrations will increase too, until eventually they’ll weaken and break, causing the tertiary structure of the proteins to change.

When an enzyme is denatured, the active site changes shape so no longer complementary to the substrate; therefore no reactions will be able to be catalysed.

Question 7

How are enzymes adapted to extreme environments

Answer 7

enzymes adapted to cold have more flexible structures, particularly at the active site, making them less stable than enzymes that work at normal temps; smaller temp changes will denature them.
Thermophiles are organisms that are adapted to working in hot, humid areas; their enzymes will be more stable because of an increases number of bonds, particularly hydrogen bonds and sulfur bridges, in their tertiary structure; the shapes of these enzymes and active sites are more resistant to change as the temp changes.

Question 8

How does pH affect enzyme activity

Answer 8

Hydrogen bonds and ionic bonds between amino acid R-groups hold proteins in their precise 3D shape; these bonds result from interactions between the polar and charged R-groups, which make up the primary structure.

Question 9

What does a change in pH refer to

Answer 9

a change in hydrogen ion concentration. The more hydrogen ions, the lower the pH (more acidic) and vice versa. The active site is at its right shape at a certain hydrogen ion conc. This is the optimum.

Question 10

What’s renaturation

Answer 10

When the pH returns back to the optimum, the protein will go back to its normal shape and catalyse the reaction again.