Final answer:
Micelles are the bile acid-lipid units that carry fat within the gut, essential for lipid absorption and re-form triglycerides within the intestinal cells.
Step-by-step explanation:
The bile acid-lipid units that carry fat within the gut are known as micelles. These structures are composed of bile salts and phospholipids that surround fatty acids and monoglycerides. Micelles play a crucial role in the digestion and absorption of lipids. Once the triglycerides are broken down, micelles facilitate the absorption by moving close to the microvilli on the epithelial cells of the intestinal wall. The fatty acids and monoglycerides then diffuse out of the micelles to re-form triglycerides within the enterocytes. These re-synthesized triglycerides are later packaged into chylomicrons for transport via the lymphatic and circulatory systems.