Return to Blog Homepage

PCAT Biological Processes – Enzyme Catalyst

  • by Sam
  • Oct 24, 2017
  • PCAT Question of the Day

An enzyme catalyst is kept in a solution buffered to the pH that maximizes activity for those enzymes found in the blood. The enzyme catalyzes a reaction that produces an acid whose pKa is 4.5. In this buffer solution, the acid product will be:

A) Primarily deprotonated

B) Primarily protonated

C) Protonated and deprotonated in roughly equal amounts

D) Not formed

 

Click for Explanation

The blood has a pH around 7.4, making it somewhat basic. If this enzyme is in a solution buffered to a point to maximize enzymes found in the blood, then the buffer solution will have a pH of 7.35 to 7.45.

 

When an acid is in a solution whose pH is higher than its pKa, the acid is deprotonated, making choice (A) the correct answer.

 

B: The acid would be protonated if the buffer solution had a pH that was below 4.5

C: The acid would have equal concentrations of the acid and conjugate base form if the buffer had a pH of around 4.5

D: There’s no reason for us to assume the product wouldn’t form

Related Post

Submit a Comment

Search the Blog

Free Consultation

Interested in our Online MCAT Course or one of our One-on-One MCAT Tutoring packages? Set up a free consultation with one of our experienced Academic Managers!

Schedule Now

Popular Posts

Free MCAT Practice Account

Need great MCAT practice?

Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.

Learn More

Sign-up for our newsletter!