Overview of lipid metabolism.
There are two major functions of lipid, energy production and structure building. Please explain:
- the overview of lipid metabolism (just in a diagram)
- Fate of triacylglycerol into adipose tissue, liver, and muscle.
- Can the triacylglicerol and fatty acid through in blood plasma as an independent triacylglycerol and independent fatty acid? Why?
Obesity. A 19-years-old woman sought medical help because she was 30 kg overweight. Most of her excess weight was in form of adipose tissue tryglycerides. A dietary history revealed that the diet was extremely poor. Much of her caloric intake was carbohydrate such as candy, cookies, cake, soft drinks, and beer.
How is it possible to form excess amount of triglyceride in the body if a diet contain predominantly carbohydrate? Explain the pathway of this process!
What are the regulatory (enzymes and hormones) influence this obesity (fat store).
What is the name of each process?
Digestion and absorption of lipids. Lipids are defined by their good solubility in organic solvent. Why do the lipids have good solubility in organic solvent and poor in water?
Poor solubility in water present problem for digestion because the substrate are not easily accessible to the digestive enzymes in aqueous phase. How do the triacylglycerol can be digested? What kind of substance do help it process? What does the bile acid for?
Please explain 5 (five) steps for delivering triacylglycerol into blood stream (from lumen into enterocyte then lymph and blood stream, including the regulatory of this process).
What do you know about chylomicrons?
Biosynthesis of triacylglycerol and its regulation. Triacylglycerols are synthesized in most tissues from active fatty acids and phosphorylated three-carbon product of glucose catabolism. Most tissue in human body can convert fatty acids to triacylglycerols by common sequence of reaction. Please explain the steps of biosynthesis palmitic from acetyl-CoA! After palmitic is formed, change it into triacylglycerol! Please explain it including the regulatory!
Where does this lipogenesis process occur? Can the acetyl-CoA enter the cytosol? Please explain it clearly including the regulatory!
Synthesis of fatty acid from glucose and net equation. After a person has ingested large amounts of sucrose, glucose and fructose that exceed caloric requirements are transformed to fatty acids. This fatty acid synthesis consumes acetyl-CoA, ATP, and NADPH. How are these substrances proceed from glucose?
Write the net equation for biosynthesis of palmitate in the rat liver, starting from mitochondrial Acetyl-CoA!
When do the fatty acids change into triacylglycerol and store in tissue and when do triacylglycerols break-down? what are regulatories involve on it?
Fatty acid as source of energy: Β-oxidation. Fatty acids can produce energy through β-oxidation. Why are this process called by β-oxidation? what is the source of fatty acids? Please explain the oxidation process to proceed energy (from fatty acid to CO2 and H2O)!
Where this process take place?
Can the fatty acid enter to mitochondrion directly? Why? How can It enter to mitochondrion?
Please write the energy that be produced by palmitate oxidation!
Energy in Triacylglycerols On a per-carbon basis, where does the largest amount of biologically available energy in triacylglycerols reside: in the fatty acid portions or the glycerol portion? Indicate how knowledge of the chemical structure of triacylglycerols provides the answer.
Fuel Reserves in Adipose Tissue Triacylglycerols, with their hydrocarbon-like fatty acids, have the highest energy content of the major nutrients.
(a) If 15% of the body mass of a 70.0 kg adult consists of triacylglycerols, what is the total available fuel reserve, in both kilojoules and kilocalories, in the form of triacylglycerols? Recall that 1.00 kcal _ 4.18 kJ.
(b) If the basal energy requirement is approximately 8,400 kJ/day (2,000 kcal/day), how long could this person survive if the oxidation of fatty acids stored as triacylglycerols were the only source of energy?
(c) What would be the weight loss in pounds per day under such starvation conditions (1 lb _ 0.454 kg)?
Consequences of a High-Fat Diet with No Carbohydrates. Suppose you had to subsist on a diet of whale blubber and seal blubber, with little or no carbohydrate.
(a) What would be the effect of carbohydrate deprivation on the utilization of fats for energy?
(b) If your diet were totally devoid of carbohydrate, would it be better to consume odd- or even-numbered fatty acids? Explain.
Fat Loss during Hibernation Bears expend about 25 _ 106 J/day during periods of hibernation, which may last as long as seven months. The energy required to sustain life
is obtained from fatty acid oxidation. How much weight loss (in kilograms) has occurred after seven months? How might ketosis be minimized during hibernation? (Assume the oxidation of fat yields 38 kJ/g.)
Biosynthesis of cholesterol and its regulation. Cholesterol is the precursor of all other steroids in the body, e.g., corticosteroids, sex hormones, bile acids, and vitamin D. It also plays an important structural role in membranes and in the outer layer of lipoproteins. What is cholesterol structure? Explain with the 5 major groups that should be in this structure!
If you eat carbohydrate, please explain the biosynthesis of cholesterol in your body, including enzymes that involve. And where does this process take place?
Case:
An adult human on a low cholesterol diet typically synthesizes 600 mg of cholesterol per day in the liver. If amount of cholesterol in diet is large, de novo synthesis of cholesterol is drastically reduce. How is this regulation brought about?
