Enzymes

Question 1

Catalyst

Answer 1

Chemical substance that increases the rate of reaction without being changed or used up.

Question 2

Enzymes

Answer 2

Proteins that function as biological catalysts, used in digestion or building up larger molecules. They are produced intercellularly in ribosomes. They work intercellularly in respiration or extracellularly in digestion.

Question 3

Lock and key model

Answer 3

Enzymes work on reactions by fitting onto the active site of the substrate. Enzymes and substrates are complementary to each other, and fit to form enzyme-substrate complexes. Enzymes then leave forming products.

Question 4

Properties of enzymes

Answer 4

They are all proteins. They can be reused. They are specific to one substrate: they can only catalyse one chemical. They denature at high temperatures and unsuitable PHs, due to hydrogen bonds breaking down - this is irreversible. They work best at a particular PH and temp.

Question 5

Effect of temperature

Answer 5

Rate of reaction increases with temperature as enzymes gain more kinetic energy and collide more often. The peak on a graph is the optimum temperature: temp. that rate of reaction is highest at. After optimum temperature is reached, enzymes become denatured. Less ES complexes are formed, rate of reaction gradually decreases to a stop. Human enzymes usually have an optimum temp. of 37.

Question 6

Effect of PH

Answer 6

There is a small range of of PH that an enzymes can work at. Rate of reaction increases as you get closer to optimum PH - the peak on a graph is the optimum PH -rate of reaction is highest - beyond optimum PH - denatured. less ES complexes - rate of reaction decreases.