IMAT 2011 Q48 [Glycolysis]

The statements below show three stages in glycolysis.

  1. 2 x 3 carbon compounds
  2. 6 carbon compound
  3. phosphorylated 6 carbon compound

The correct sequence is:

A. 1, 2, 3

B. 2, 3, 1

C. 3, 2, 1

D. 1, 3, 2

E. 2, 1, 3

Glycolysis is the metabolic pathway that converts glucose C₆H₁₂O₆, into pyruvate, CH₃COCOO⁻ H⁺. The free energy released in this process is used to form the high-energy molecules ATP and NADH. Glycolysis is a sequence of ten enzyme-catalyzed reactions (unnecessary to memorize for the IMAT, but good luck in med school).

We have three statements that we should sequence in the right order. We know that glycolysis in the making of pyruvate (enter product, 3 carbon compound) from glucose (start product, 6 carbon compound) with phosphorylation (the adding of the phosphate groups on the glucose for making it unstable and force it to split into two 3 carbon sugars) this process, of course, is much more complicated, but you should only know the primary route of glycolysis, understanding the inputs and outputs of the cycle, and not memorize the entire metabolic pathway.

So, glucose enters and gets phosphorylated, then turns into 2x3 carbon compounds (pyruvate) the process is consuming 2 ATP, and making 4 ATPs, giving us a total net worth of 2 ATP, 2 NADH, and 2 pyruvate molecules.

I am attaching a picture from KhanAcademy which demonstrates the parts of glycolysis which should, in my opinion, be memorized for the exam.