Exam #2 In-Class Questions

Question 1

A researcher mutated a critical domain on the Na+/K+ -ATPase gene. When expressed in cells, the mutated protein was unable to form the E-P intermediate in the reaction cycle of the enzyme. Which of the following amino acids was most likely altered in the mutant protein?

a. Asparagine
b. Aspartate
c. Glutamate
d. Alanine
e. Tryptophan

Answer 1

b. Aspartate

Question 2

A 60 year old man arrived to the emergency room complaining of chest pain, shortness of breath and swelling of the legs. Echocardiography results showed evidence of congestive heart failure. The attending physician immediately started him on Digitalis. Which ion transporter/channel is the primary target of this drug?

a. Sodium calcium exchanger
b. Sodium potassium ATPase
c. Sodium channel
d. Plasma membrane calcium ATPase
e. Sarcoplasmic Reticulum Calcium ATPase

Answer 2

b. Sodium potassium ATPase

Question 3

During his summer vacation in Hawaii, Dr. OshKosh was bit on his left arm by a puffer fish as he was swimming in the beautiful blue waters. His entire arm was immediately numb. Which type of transport protein was impacted by the toxin in the puffer fish?

a. sodium channels
b. potassium channels
c. calcium channels
d. chloride channels
e. water channels

Answer 3

a. sodium channels

Question 4

Which step in the function of the K+ channel is controlled by the ball and chain mechanism?

a. activation
b. voltage
c. potassium-binding
d. inactivation

Answer 4

d. inactivation

Question 5

A patient’s enzyme deficiency has led to a decrease in cytosine triphosphate (CTP) causing a roadblock in gene expression. Levels of dihydroorotate remain normal. Which of the following enzyme is most likely defective?

a. ATCase
b. IMP synthase
c. UMP synthase
d. Dihydroorotase
e. Ribonucleotide reductase

Answer 5

c. UMP synthase