MCQ Microbiology Answer 34

The answer is: B

Adenosine triphosphate (ATP) is believed to be generated at three reaction points in the electron transport chain: the reductions of flavoprotein, cytochrome b, and cytochrome c. This phenomenon, demonstrated in experiments with mammalian mitochondria, can be expressed in terms of the relationship between the moles of ATP generated for each atom of oxygen consumed—the P/O ratio.

In mammalian cells, the P/O ratio is 3; that is, there are three segments in the electron transfer chain in which there is a relatively large free energy drop. In bacteria, however, there appears to be only one or two of these segments. Loss of these phosphorylation sites as well as reactions that bypass these sites of ATP synthesis account for the lower P/O ratio in bacteria. Some bacteria, such as Mycobacterium phlei, have P/O ratios of 3.

Category: Microbiology MCQs