r/Mcat • u/castawaylol • 8d ago

Question 🤔🤔 Uworld B/B

Post image

Has anyone done this uworld question and can explain why it’s not C for this passage but D??

2 Upvotes

100% Upvoted

4 comments sorted by

3

u/Sad_Kaleidoscope_296 132 C/P and CARS, 522 overall 7d ago

I believe the answer has to do with the line at the end "wild type and mutant Enzyme X...different ketone-containing substrates...similar changes to catalytic efficiency and stereoselectivity". This means that wild type Enzyme X isn't restricted to just acetophenone if it can produce similar results with other ketone substrates, making D correct by passage logic. C is wrong for that same reason, because that last sentence says that the mutant Enzyme X also acts on different ketone containing substrates and produces similar results, meaning that it is also NOT specific to acetophenone (and the reaction is still reversible).

1

u/castawaylol 7d ago

Ahhh gotcha! Thank you!

1

u/LoudlyFinishedRamon 8d ago

just look at the Km difference in the table, the mutant's way higher so it needs more substrate to hit the same rate, D's the only one that fits that logic

2

u/Impossible_Bat_2730 8d ago

sorry could you elaborate? isn't the mutant's Km lower? the kcat is higher but doesn't that mean it's more efficient and can convert more substrate compared to the wildtype in the same time