Biochemistry?

Question

1. What is the biochemical reaction that enables cells to consume O2, using NADH as the electron donor?

2. What is the molecule that is removed from the citric acid cycle, transported to the cytoplasm where an enzyme converts into acetyl-SCoA for fatty acid synthesis?

Answer 1

1. The last reaction of electron transport chain is-  

NADH + H+  + 1/2 O2 ---------------  NAD+  +  H2O

2. Citrate

Inside the mitochondrial matrix; acetyl-coA combines with oxaloacetate to form citrate (enzyme- citrate synthase). Citrate is transported to cytosol by citrate transporter. In the cytosol, it is converted back into acetyl-coA and oxaloacetate (enzyme- citrate lyase). This 2nd reaction (one taking place in the cytosol) requires ATP.

Acetyl-coA; thus formed; is used for fatty acid synthesis. Oxaloactate is converted into malate and malate is transported back into mitochondria by malate shuttle.