Enzymes HL1

What is an active site?

• The part of an enzyme that binds only to the product molecules

• The sequence of amino acids responsible for the catalytic activity of enzymes.

• The sequence of amino acids responsible for the structure of an enzyme

• The specific area responsible for the activity of all proteins

According to the induced fit model of enzyme function, which of the following statements is correct?

• Active sites on enzymes are specific to a single substrate.

• The shape of the active site can be changed by the binding of an allosteric inhibitor.

• The binding of the substrate changes the shape of the active site slightly.

• Competitive inhibitors can change the shape of enzymes.

The graph shows the results of an investigation into the activity of turnip peroxidase. The accumulation of the product of the reaction catalysed by the enzyme is shown at different pH values. Based on the data in the graph, what is most probably the optimum pH for turnip peroxidase?

• Between 3 and 5

• Between 10 and 11

• Between 7 and 8

• Between 9 and 10

The graph shows the effect of substrate concentration on the rate of an enzyme-catalysed reaction with and without an inhibitor. What do the curves J, K and L on the graph indicate?

• Competitive inhibitor J, Noncompetitive inhibitor K, Normal enzyme activity L

• Competitive inhibitor K, Noncompetitive inhibitor L, Normal enzyme activity J

• Competitive inhibitor L, Noncompetitive inhibitor J, Normal enzyme activity K

• Competitive inhibitor L, Noncompetitive inhibitor K, Normal enzyme activity J

Tags

NGSS.HS-PS1-5

Three flasks were prepared for an analysis of the activity of amylase. At time zero, each of the substances indicated in the diagrams was added.

Which flask(s) could provide support for the hypothesis that heat denatures enzymes?

• Flasks I and II after 15 minutes

• Flasks II and III after 15 minutes

• Flasks I and III after 15 minutes

• Flask III at time zero and again after 15 minutes

Isoleucine will inhibit the reaction pathway shown below when the concentration of isoleucine exceeds the cell requirements. Which enzyme does isoleucine inhibit?

• Enzyme E1

• Enzyme E2

• Enzyme E3

• Enzyme E5

Pancreatic gland cells produce and secrete large amounts of digestive enzymes. Which organelles would you expect to be present in higher than normal amounts in such cells?

• Free ribosomes and Golgi apparatus

• Rough endoplasmic reticulum and lysosomes

• Rough endoplasmic reticulum and Golgi apparatus

• Free ribosomes and lysosomes