LIPIDS

Commonly referred to as “FATS” Insoluble in water, soluble in organic solvents Transported by lipoprotein in the body

Lipids are not soluble in water and only soluble in organic solvents because lipids do not have any polar group. Lipids contain several hydrocarbon atoms that makes them hydrophobic. Only organic solvents like chloroform, benzene hexane methanol ethanol can dissolve lipids. In the plasma the major lipids found are cholesterol, triglycerides, and phospholipids n non-esterified fatty acids since they are insoluble in water. You wouldn’t find large amount of lipids circulating in the plasma need to be carried by lipoproteins from one organ to another. When they are found in the plasma, Lipoprotein acts as transporters or carriers of diff lipids in plasm.

Significant of lipids in the body:

Rich source of energyo Composed mostly of C-H bonds

In form of TAGS , released large amounts of energy compared to carbohydrates , they are able to storage energy efficiently and more compact form compared to carbohydrates, why? because They are not easily dissolved by water. When are cleave and broken down large amount of energy generated from them. Unlike carbo

Structural role in cellso Part of cell membrane

Maintaining structural integrity to the cells by the form of phospholipids, Thermal insulators

o In subcutaneousRefer to Triglycerides ,Prevent loss of heat when individual exposed to very low temperatures

Precursor of other physiologically functional substance

Cholesterol serve as precursor for steroid hormones. Also Acts as activators of several cellular rxnreferring steroid hormones attached to receptors that re found in cytoplasm of their target cells.

As hormoneso Prostaglandins are derived from unsaturated fatty acids

Fatty acids are uniquely identifiable because made of single bonds, usually even #, made up of several hydrocarbon atoms end with single carboxy.l FA are defined Monocarboxylic acid with even # carbon atoms. Even # ? because every time they are synthesize in cytoplasm from acetyl COA. 2 carbon mol are incorporated or attached from previous FA mol coming from acetyl COA. Formation of FA comes from Citrate which the precursor is Acetyl COA. So, citrate has to cleave the mitochondria finding its way to the cytoplasm and it is in the cytoplasm where 2 mol of carbon atoms are attached to form FA.

Linear Chain of C-H bondsTerminal with carboxyl group(-COOH)

*agentiakfo.wordpress.com (picture, structure)

Depending on where they are located

Esterified fatty acids

Majority of plasma fatty acids are constituents of triglycerides or phospholipids Covalently attached to backbone of TGL and PPlby an ester bond

That are attached to the other lipid mol like triglycerides and phospholipids.IF FA are found in lipid mol these are esterified Why esterified ? kayang manner of attachment is thru the ester linkage .

NEFA (Non-esterified fatty acids)

Considered as the simplest lipids Only a small amount exist in the body

Common FA as monocarboxylic wityh 3 membered carbon atomsKnown as free FABCOZ not attached to any lipid mol.

CLASSIFICATIONS:

According to length:o Short chain – 4 to 6 carbon atoms

Synthesis occur cytoplasm

o Medium chain – 8 to 12 carbon atomso Long chain - >12 carbon atoms

Synthesis Occur in smooth ER ,so continuation of adding 2 carbon mol to short chain length FA in order to them to lengthenoccur Smooth ER . So the short length FA from the cytoplasm enter in smooth ER and incorporation of 2 carbon mol from acetyl COA continues in the smooth ER. Most naturally occurring FA have a chain of 11 carbon atoms and usually range from 4 to 28 carbon atoms per FA. In the diet usually long chain length.

According to carbon double bond contento Saturated – no carbo double bonds

Saturated fatty acids are saturated with hydrogen

FA carbon carbon single bondo Unsaturated

Monounsaturated – 1 carbon double bond Polyunsaturated – >/= 2 carbon double bonds

FA carbon carbon double bond . Are easier to metabolize compared to saturated FA. Bcoz when the unsaturated FA folds the double bonds of the structure it creates a kink or space . The space are areas where the double bonds are cleaved. That why they are not as compact compared to saturated fats . They are liquid at room temp. Unlike saturated FA made of single

bonds when they fold are they more compact. No spaces in the structure .Harder or the single bonds to be destroyed . Solid at RT. Reason why when you are conscious about ur diet u rather eat containing unsaturated FA compared to saturated FA. But then you have to identifydapat unsaturated FA if its trans or cis . Trans fat, it’s a unsaturated FA contains double bonds when folds it folds compact similar to saturated fats . Also , solid at RT. Even if it has double bonds they are hard to metabolize compared to cis unsatfats . The hydrogen atoms attached to the carboncarbon double bonds of the opposite sides. Since the hydrogen are attached to the opposite sides when it folds even it contains double bonds if the folding in the area is not much that compared to cis unsat fat.

You’ll immediately know that its unsat fat becoz there is a kink or space in the structure so if the structure is linear usualy it’s a single single carbon bond it’s a saturated fat but if there is a kink or may nakiwisa structure the area that is where nagkiwisastructure usually the double bond is located at the one you see sa picture sa slide. In this case, cis unsatfat , hydrogen atoms attached to the double bond when it folds mas dakoang space niyabcoz the hydrogen bonds are on the same side. Unlike kung trans, opposite side kung ma fold siya mas gamayang space. The trans fat are like saturated fatty acids. Food that are sold that contains trans fat it increases that shelflife of the food and also the flavor.that why the more mananamang

foodthe higher the trans fat it contains food. If u want to be healthy then the amount of trans fat that should be taken is 2grams of trans fat per day . It’s the only maximum amount I can metabolize . So if u eat excess that remaining is u need to exercise. Sat FA are linear in structure as u can see for steric acid the more kink in the struc like oleic , linoleic and linolenic the more bent . Plasma Membrane may head and tail angisatadlongangisagakiwi meaning ang is aka fatty acid dirasi saturated FA angisa unsaturated FA.

Unsaturated fatty acids

Cis fatty acidso Both H atoms on the same side of the C=C double bondo More fluid compared to trans fatty acids

Triglycerides

3 fatty acids attached to glycerol by ester bond

FA that are attached to glycerol are considered to be esterified FA bcoz they are FA but they are attached thru ester linkage to glycerol. Perokung ificleavesila sang lipase sa ester linkage kangmaseparatediri then becomes non esterified FA or free FA. So there are 3 esterified FA attached to triacylglycerol. If the FA are saturated then the TAGS are solid at room temp. they are compact but if the FA that are found in unsaturated FA then the TAGS are liquid at RT. They form oils. And sometimes there is a mixture of both unsat and sat FA. The formation of TAGS occur in the liver . When 1 mol of glycerol and when there are 3FA avail attached to carbon atoms of glycerol. You have Notice releases of H2 .to form 1mol of glycerol attached to FA.

Hydroxyl carboxyl COOH ester……... hydrogen OH makakas . It’s a DEHYDATRATIO Rxn.

The triglycerides is formed and the liver is called Endogenous fats bcoz form within the body.TAGSthat are taken in by the body from food are Exogenous. So the trig in the slide is what type a fat a oil or mixed fat ?its a mixed triglyceride bcoz u have 2mol of sat fat and 1mol unsat fat .If u check the structure of triglyceride none of the structure or any part are not capable of interacting with water puro hydrocarbons. So TAGS is purely hydrophobic. And when TAGS are delivered to the adipocytes . They are the storage of lipids. So ,carriers of triglycerides in the plasma will be dependent on the type of TAGS that are circulating if that TAGS comes from the foods that we eat then the carrier for exogenous fats are chylomicrons . But triglycerides that arte from in the liver are endogenous fats are carried by VLDL( Very Low Density Lipoprotein).

Hydrophobic Main form of lipid storage in man

o 95% of adipose tissue Transported mostly by chylomicrons (exogenous) and VLDL (endogenous)

TGL with saturated fatty acidso Solid at RTo Animal sources

TGL with unsaturated fatty acidso Oil at RTo Plant sources

Corn, sunflower seeds, safflower seeds oils

LDL cholesterol, the “bad” cholesterol oxidizes in the artery wall. – It appears that people who consumed 23ml – about 2 tablespoons of virgin olive oil daily showed less oxidation of LDL cholesterol

Phospholipids

Two fatty acids attached to glycerolo One is saturated and one is unsaturated

3rd position of glycerol contains a phospholipid head group

Phospholipids are amphipathic molecules Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid

bilayers

Cholesterol

Unsaturated steroid alcohol containingo Four rings:

A Contains a hydroxyl (-OH) group Only hydrophilic part of cholesterol

B C D

o C-H side chain tail

Cholesterol could either be:o Unesterified

30-40% Amphipathic

o Esterified 60-70%

COOH group conjugated by an ester bond to a fatty acid Hydrophobic

Transported in the body by:o LDL (60-70%)o HDL(20-35%)o VLDL (5-12%)

Almost exclusively synthesized by animals Not a source of fuel

o Not readily metabolized by cells Functions:

o Can be converted in the liver to bile acids Fat absorption in the intestines

o Precursors substance of steroid hormones Glucocorticoids, mineralocorticoids and estrogen

o Can be transformed to vit D3 after irradiation of skin to sunlight