Question 18

Describe the generation of ATP by mitochondria (50% marks) and outline the processes by which ATP is generated in red blood cells (50% marks).

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College Answer

Excellent answers focused on oxidative phosphorylation and the chemiosmotic mechanism in their description of ATP production by mitochondria. This required a description of the structure of the mitochondrial components involved in ATP production, the establishment of an electrochemical gradient of protons across the inner membrane, how the electron transport chain works and its components, and
the roles of cytochrome oxidase and ATP synthase. Excellent answers describing ATP generation in red blood cells focused on anaerobic glycolysis in the absence of mitochondria, with an emphasis on the key steps that consume or produce ATP. The role of lactate dehydrogenase in regenerating NAD+ was also emphasised. Some candidates described other pathways of metabolism that do not generate ATP, for which no marks were awarded.