Final answer:
Lipogenesis is the synthesis of fatty acids and triglycerides from acetyl CoA, occurring in adipocytes and hepatocytes. Glycerol and fatty acids are formed during the breakdown of triglycerides in lipolysis, which precedes their respective metabolic pathways.
Step-by-step explanation:
Lipogenesis and Metabolic Pathway
Lipogenesis is the process of synthesizing fatty acids and triglycerides from acetyl CoA, primarily in the cytoplasm of adipocytes (fat cells) and hepatocytes (liver cells). It occurs when glucose levels are high, and the body converts excess acetyl CoA from glycolysis into fats for storage. During lipogenesis, acetyl CoA is incrementally built up into fatty acids by the addition of two-carbon fragments, using ATP in the process. Subsequent enzymatic reactions lead to the formation of triglycerides, which are then stored in adipose tissue.
Glycerol and fatty acids are formed during the breakdown of triglycerides, a process known as lipolysis. This occurs before their respective pathways; glycerol can be converted into glucose through gluconeogenesis, while fatty acids undergo ß-oxidation to produce acetyl CoA, which then enters the citric acid cycle or is used for ketogenesis.