7. Energy and Metabolism

Which of the following are examples of the functions of enzymes?

a) A lactase enzyme breaking down lactose sugar in the small intestine.

b) A DNA polymerase enzyme synthesizing new strands of DNA.

c) A lipase enzyme breaking down fats (lipids) in the small intestine.

d) A helicase enzyme unraveling DNA so it can be replicated.

e) All of the above.

Which characteristics are likely associated with an enzyme isolated from a human stomach where conditions are strongly acidic.

a) An enzyme that functions properly at 70 degrees Fahrenheit and at a neutral pH.

b) An enzyme that functions properly at 98 degrees Fahrenheit and at an acidic pH.

c) An enzyme that functions properly at 98 degrees Fahrenheit and at a neutral pH.

d) An enzyme that functions properly at 70 degrees Fahrenheit and at an acidic pH.

Enzymes usually function best at an optimal pH and temperature. The following graph shows the effectiveness of two enzymes at various temperatures. (c) From what you know about enzyme structure, explain why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40°C (140°F).

Enzymes usually function best at an optimal pH and temperature. The following graph shows the effectiveness of two enzymes at various temperatures. (b) One of these enzymes is found in humans and the other in thermophilic (heat-loving) bacteria. Which enzyme would you predict comes from which organism?

Enzymes usually function best at an optimal pH and temperature. The following graph shows the effectiveness of two enzymes at various temperatures. (a) At which temperature does enzyme A perform best? Enzyme B?