There are major eight steps in TCA cycle. Oxaloacetate plays a pivotal role in <u>first and eight step</u>s of cycle.
Step 1. In the first step of the citric acid cycle, acetyl CoA joins with a four-carbon molecule, oxaloacetate, releasing the CoA group and forming a six-carbon molecule called citrate.
Step 8. In the last step of the citric acid cycle, oxaloacetate—the starting four-carbon compound-is regenerated by oxidation of malate. Another molecule of NAD+ is reduced to NADH in the process.