Chapter 17: Fatty Acid Catabolism Overview of fat digestion, mobilization, and t

Question

Chapter 17: Fatty Acid Catabolism Overview of fat digestion, mobilization, and transport (Chylomicrons, Definition, structure of fatty acids, triacylglycerols, advantages of storage of TAG's vs. sugar Steps in signaling pathway leading to lipase digestion of in lipid droplets (glucagon o epinephrine dependent phosphorylation of perilipins and activation of hormone sensitive lipase) Activation of fatty acids P 14 C) for transport into mit via carnitine shuttle. ATP cost of activation Know how B oxidation fits into overall stages of oxidation, what is the fate ofthe glycero? The carbo chain? Which is glucogenic, which is ketogenic? Write the four reaction steps of B-oxidation, using structures to describe the intermediates where doe B-oxidation occur in the cell? Use the co stoichiometry to show the final products derived from one saturated fatty acid molecule T4 C). Identify the enzyme and any required cofactors for each step.

Explanation / Answer

Fat Digestion mobilisation and transport

Triacylglycerols in the body are gotten fundamentally from:

1. The Diet

2. Biosynthesis

3. adipocytes (storage)

Pancreatic Lipase acts to hydrolyze triacylglycerols at positions 1 (last purpose of hydrolysis) and 3 (first purpose of hydrolysis). The results of this response are Na+ and K+ salts of unsaturated fats (otherwise called cleansers). Cleansers, obviously, help emulsify fats. Facilitate, the movement of pancreatic lipase really increments when it contacts the lipid-water interface (interfacial actuation). Official of pancreatic lipase to the lipid-water interface requires a complex with another variable, pancreatic colipase. Without substrate (lipids), the chemical complex's dynamic site is covered by a top like structure. In the present of lipid, the dynamic site is uncovered and in the process a hydrophobic access to the dynamic site is uncovered.

Keep in mind that a micelle is framed when cleansers encompass a non-polar substance in water. Lipid assimilation by pancreatic lipases produces mono and diacylglycerols that are caught up in the small digestive tract. Bile acids help in this procedure as well, shaping micelles. Blocked bile pipes restrain ingestion of fats impressively. Keep in mind likewise that vitamins A,D,E, and K are fat solvent, and their ingestion too is subject to bile acids. Once inside the intestinal cells, unsaturated fats complex with a protein in the cytoplasm called intestinal unsaturated fat restricting protein (I-FABP) that expands their viable solvency and shields the phone from their cleanser impacts.

Pressing into Chylomicrons:

The mono and diacylglycerols in the stomach related cells are changed over back to triglycerides, and bundled into lipoproteins in the circulatory system called chylomicrons . They go into the circulatory system by means of the lymph framework. Triacylglycerols are additionally orchestrated by the liver where they are bundled as low thickness lipoproteins (VLDLs) and discharged into the blood. Upon entry in fat tissue and muscle cells, lipoprotein lipase cuts them to free unsaturated fats and glycerol. Unsaturated fats are taken up by these tissues and glycerol is transported to liver or kidneys where it is changed over to dihydroxyacetone phosphate (glycolysis middle of the road) by glycerol kinase (puts phosphate on) and glycerol-3-phosphate dehydrogenase (oxidizes to DHAP). In fat tissue, hydrolysis of fats to unsaturated fats and glycerol is proficient by hormone-touchy triacylglycerol lipase. Free unsaturated fats are discharged there into the circulatory system where they tie to egg whites.

Lipoproteins :they edifices convey lipids in the circulation system .Almost no free lipid can be recognized in the blood. The protein parts of the lipoproteins are combined in the liver and intestinal mucosa cells. Classes of lipoproteins and their properties .. Lipoproteins frame micelles with lipids as a system of transporting them in the fluid condition of the blood. The five classes of lipoproteins are condensed beneath:

1. Chylomicrons - transport dietary fats and cholesterol from digestive organs to tissues.

2. Low Density Lipoproteins (VLDL) - transport endogenous fats and cholesterol from liver to tissues

3. Transitional Density Lipoproteins (IDL) - transport endogenous fats and cholesterol from liver to tissues

4. Low Density Lipoproteins (LDL) transport endogenous fats and cholesterol from liver to tissues

5. High Density Lipoproteins (HDL) transport endogenous cholesterol from tissues to liver.

Chylomicrons - collect in intestinal mucosa, convey exogenous fats and cholesterol through lymph framework to extensive body veins (See Figure 18.7). Chylomicrons cling to inward surface of vessels of skeletal muscle and fat tissue (fat cells) (See Figure 18.6). Fats contained inside them (yet not cholesterol) are hydrolyzed by lipoprotein lipase, liberating unsaturated fats and monoacylglycerol. The staying contracted chylomicron structure is known as a chylomicron leftover, which contains cholesterol and separates from the hairlike endothelium and reenters the course framework where it is taken up by the liver. Along these lines, chylomicrons convey dietary fats to muscle and fat tissue. They likewise convey dietary cholesterol to the liver.

VLDL – they s are incorporated by the liver and, similar to chylomicrons, are debased by lipoprotein lipase. VLDL, IDL, and LDL are interrelated. IDL and LDL show up in the dissemination as VLDL leftovers. VLDL is changed over to LDL by evacuation of all proteins aside from apo B-100 and esterification of the majority of the cholesterol by lecithin-cholesterol acyl transferase (LCAT) related with HDLs. The esterification happens by exchange of an unsaturated fat from lecithin to cholesterol (framing lysolecithin). The protein parts of lipoproteins are called apolipoproteins (or apoproteins). These proteins, however water solvent, have a hydrophobic and a hydrophilic character that is evident in their alpha helices. Their alpha helical districts are settled upon fuse into lipoproteins. The lipids seem to balance out the helices since they are made out of hydrophobic amino acids on one side of the helix (confronting the lipid) and hydrophilic amino acids on the other (confronting water).

Cholesterol Uptake :   Cholesterol makes it to creature cell layers by either outside exchange, or by cell blend . Exogenous cholesterol achieves cells from LDL. LDL ties to cell LDL receptor, a transmembrane glycoprotein that ties both ApoB-100 and apoE. LDL receptors frame bunches of "covered pits" .. Clathrin, the framework protein of the covered vesicles that exchange proteins amongst RER and the Golgi mechanical assembly, shapes the support of the covered pits. The covered pits invaginate into the plasma layer, shaping covered vesicles that wire with lysosomes. This procedure is known as receptor intervened endocytosis .. Inside the lysosome, cholesteryl esters are hydrolyzed, yielding free cholesterol, which can be consolidated into cell films. Overabundance cholesterol is reesterified for capacity. Curiously, high intracellular cholesterol smothers combination of LDL receptor and biosynthesis of cholesterol, two elements that anticipate overaccumulation of cholesterol in cells.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.