Final answer:
The purpose of the second phase of the citric acid cycle is to further oxidize the carbon-carbon bonds in citrate, releasing two molecules of carbon dioxide (CO₂). This phase consists of steps 2 and 3 of the cycle.
Step-by-step explanation:
The purpose of the second phase of the citric acid cycle is to further oxidize the carbon-carbon bonds in citrate, releasing two molecules of carbon dioxide (CO₂). This phase consists of steps 2 and 3 of the cycle.
In step 2, citrate is converted into its isomer, isocitrate, by losing one water molecule and gaining another.
In step 3, isocitrate is oxidized, producing a five-carbon molecule called α-ketoglutarate, one molecule of CO₂, and two electrons that reduce NAD⁺ to NADH.