Question

In Mediterranean countries, it is traditionally recommended to drink a glass of olive oil per day to stay healthy. Consider that olive oil is made of 100% of triglycerides. Among the fatty acids contained in these triglycerides, 70% are oleic acid (monounsaturated fatty acid with 18 carbons), 10% are linoleic acid (polyunsaturated fatty acid (2 unsaturations) with 18 carbons) and linolenic acid (polyunsaturated fatty acid (3 unsaturations) with 18 carbons), 10% are palmitic acid (saturated fatty acid with 16 carbons), and 10% are stearic acid (saturated fatty acid with 18 carbons).

B. Explain how these triglycerides are digested in the intestine. 

C. Explain how these lipids are distributed to peripheral tissues (explain in detail how these lipids are transported from the intestine to the peripheral tissues (or extra-hepatic tissues) : how they are transported in the bloodstream and how they are distributed to the peripheral tissues) 

D. Explain the different fates of these fatty acids in the post-prandial period in the following organs: a) skeletal muscles, b) adipose tissue and c) the brain. For each metabolic pathway involved, name the pathway, give the initial substrate(s) and the final product(s) and the ultimate goal of each pathway (please do not describe the whole pathway!). Then, describe the limiting step(s) of each pathway: give the substrate and the product of each limiting reaction and the name of the enzyme that catalyzes each limiting reaction. Finally, briefly explain how these pathways are regulated during the post-prandial period. (13.5 marks)

E. For each molecule of stearic acid entering a cell, theoretically, how many ATP could be produced through its complete beta-oxidation? Justify your answer. 

F. A child was born with a deficiency in β-ketoacyl-CoA transferase specifically in the brain. What do you think will be the consequences if the child is fasting for several days. First, explain in which pathway this enzyme is involved, describe the reaction catalyzed by this enzyme and then explain what will be the consequences of this deficiency. 

Answer 1

Answer:

D):

• The use of fatty acids as substrates to fuel energy production begins with their importation into the mitochondria via conjugation to carnitine by the enzyme CPT-1 and this is the rate- limiting step of beta- oxidation.
• Sarcoplasmic short and medium-chain fatty acids (chain lengths up to 12 carbons) can freely enter the mitochondrial matrix.
• In contrast, long-chain fatty acids must be transported into the mitochondria by the carnitine shuttle, which is a rate-limiting step.

F):

• It's a metabolic disease. This enzyme need for the ketone body metabolizing.
• Ketone body used as a source of energy when glucose level low in body.
• When the absent of this enzyme the accumulation of the ketone in the body is called keto acidosis.
• So this caused the by the physical stree, fasting, illness, low carbohydrates diet etc.
• Then the symptoms arise like rapid breathing, poor feeding, vomit, lethargy.
• When long fasting that time glucose not provide energy to body so that that time body fat break down into the ketone for energy source but ketone can't be used up body because of deficiency of this enzyme so that ketone accumulation in blood and urine.
• This cause the diabetes.