58 613
Assignments Done
Successfully Done
In March 2018
Your physics homework can be a real challenge, and the due date can be really close — feel free to use our assistance and get the desired result.
Be sure that math assignments completed by our experts will be error-free and done according to your instructions specified in the submitted order form.
Our experts will gladly share their knowledge and help you with programming homework. Keep up with the world’s newest programming trends.

Answer on Biochemistry Question for sarah

Question #38994
After not eating all day and feeling absolutely famished, you eat a meal high in vitamin A. Predict and explain what type of transport process (described in class; ie, simple diffusion, facilitated diffusion, or active transport) that you expect the vitamin to use to cross your intestinal membranes.
Expert's answer
Dietary retinyl esters are hydrolyzed in the intestine by the pancreatic enzyme: pancreatic triglyceride lipase (PTL), and intestinal brush border enzyme: phospholipase B. Unesterified retinol is taken up by the enterocytes, perhaps involving both simple diffusion (due to solubility of retinol in the lipid bilayer) and protein-mediated facilitated transport. However, until now, no protein has been identified and characterized that might be involved in the uptake of retinol. Once in the cell, retinol is complexed with cellular retinol-binding protein type 2 (CRBP2) and the complex serves as a substrate for reesterification of the retinol by the enzyme lecithin:retinol acyltransferase (LRAT). Retinol not bound to CRBP2 is esterified by acyl-CoA acyltransferase (ARAT). The retinyl esters are incorporated into chylomicrons, intestinal lipoproteins that transport other dietary lipids such as triglycerides, phospholipids, and cholesterol. Chylomicrons containing newly absorbed retinyl esters are then secreted into the lymph.

Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!


No comments. Be first!

Leave a comment

Ask Your question