Describe the digestion of fat in the intestine, and the transport of fats through the epithelium into the bloodstream.
What will be an ideal response?
Ans: Lipid digestion is mostly accomplished by pancreatic lipase, but efficient digestion of the fat requires emulsification by the bile salts from the liver. Digested free fatty acids are transported through the gut lumen by micelles, created by the bile salts and phospholipids. The free fatty acids diffuse from the micelles across the apical membrane of the epithelium. Inside the epithelium, the fatty acids are recombined with glycerol to make triglycerides. These are packaged with proteins to form chylomicrons (a lipoprotein) that is released by exocytosis across the serosal wall of the epithelium. The chylomicrons enter the lacteals, and are transported via the lymphatic system to the general circulation.
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Phospholipase is an enzyme that will cleave the phosphate head group off a phospholipid molecule. The plasma membrane is not, however, permeable to the enzyme
Imagine a cell containing different phospholipids. How could you use phospholipase to determine which phospholipids are in the monolayer facing the exterior of the cell, and which are in the monolayer facing the interior (assume you have a way to assay for the different types of phospholipids)? What will be an ideal response?
How many proteins are specified in the genetic code?
a. 4 b. 5 c. 20 d. 64
The characteristic ____________________ of a radioisotope allows us to determine the age of rocks and fossils using a technique called ____________________.
Fill in the blank(s) with the appropriate word(s).
In humans, the locus of the CFTR gene is on chromosome ____
a. 7 b. 15 c. 19 d. 20 e. 29