LIPIDS AND LIPOPROTEINS

Lipids and Lipoproteins

One of the biomolecules that is considered very important in the body

Carbohydrates, lipids, and proteins

it is being utilized in our body by the cells to do their function;

also the one that produces the structure of the cell

Carbohydrates

component of plasma membrane

Lipids

component of lipid bilayer; the one you see on plasma membrane that provides a semi permeable membrane for the cells

soluble

Lipids are _______ in nonpolar organic solvents

insoluble

Lipids are relatively _________ in polar organic solvents

chloroform, ether

nonpolar organic solvents

water

polar organic solvent

nonpolar organic solvents

generally hydrophobic solvents

carbon-hydrogen bonds (C-H)

Lipids are mostly composed of what bonds?

Lipoprotein

Lipids can’t be transported in plasma thus it will need a carrier protein. What is its carrier protein?

90%

Plasma is composed of how many percentage of water?

Lipogenesis

Excess glucose inside the body is stored up through the process of?

fats

Carbohydrates will be converted to ____ as a way to store excess calories.

Cholesterol

Lipids are rich source of energy EXCEPT ___________ because it cannot be used as energy source.

Gluconeogenesis

Process needed by the body for the fats and triglycerides to be utilized as energy source

Lipids

Integral part of the cellular membrane;

Precursor to steroid hormones

Cholesterol

Main lipid

Glucocorticoids and sex hormones (e.g. testosterones, progesterone, estrogen)

Steroid hormones

Fatty acids, Phospholipids, Triglycerides, Cholesterol

Forms of Lipids

Fatty acid

has a carboxyl group at the polar end and a hydrocarbon chain at the nonpolar tail

Amphipathic

compounds that has a polar and nonpolar group;

type of compound that is water-loving and a water fearing group

Triglycerides

Most fatty acids in our body are in the form of?

fatty acid attached to glycerol

Most common form of fatty acid seen in the body

Short chain fatty acids

are usually byproduct of bacterial metabolism in gut;

predisposing factors to different diseases

Saturated, Unsaturated

2 Types of Fatty Acids

Saturated Fatty Acids

If there are only single bonds in the chain usually found in the carboxyl group; polar or water-loving group

Unsaturated Fatty Acids

If there are carbon-carbon double bonds in the chain;

the double bond is usually cis rather than trans

Cis and Trans

usually the formation or configuration of lipids

Cis

most common formation of lipids; can be seen in animals and natural food products

Trans

formation of lipids not commonly found in the nature;

chemically or synthetically being done

Hydrogenation

process of creating an unsaturated fats; creating trans fatty acids

Trans fats

dangerous in the body; it blocks the artery of the heart

the number of carbon atoms and the number of double bonds

The notation used for fatty acids indicates?

Unsaturated fatty acids

Which fatty acids have lower melting points than the other?

Unsaturated fats

Usually liquid in room temperature (e.g. cooking oil)

Saturated fats

Solid in room temperature

Phosphatidic acid

two fatty acids are also esterified to the glycerol molecule

Phosphatidyl ester

One molecule of phosphoric acid can form ester bonds both to glycerol and to some other alcohol

Phospholipid

most abundant lipid in the body; serves as a surfactant

Lecithin / Phosphatidyl choline (70%)

Sphingomyelin (20%)

Cephalin (10%)

3 most commonly found forms of Phospholipid in the body

Sphingomyelin

Only phospholipid in membranes that is not derived from glycerol but from an amino alcohol called sphingosine;

Essential component of cell membranes

liver and spleen

Sphingomyelin accumulates in the ___ __and__ ____ of patients suffering from Niemann-Pick disease.

Niemann-Pick disease

deficiency in an enzyme that metabolizes or digests the sphingomyelin, therefore the fats now will accumulate in the liver and spleen

Triglyceride

Neutral fat (No charge)

Triglyceride

Main storage of lipid in man (in adipose tissue)

3 molecules of fatty acids and a molecule of glycerol

Triglyceride possesses what molecules?

molecule of glycerol

Serves as triglyceride’s backbone

excellent insulation

Triglyceride function

lipases

Enzymes that hydrolyzes the ester linkages of triacylglycerols when an organism uses fatty acids

Acids or Bases

Catalysts of hydrolysis reaction outside organisms

Cholesterol

Not a source of fuel because it is not catabolized by animals;

It is found on the surface of lipid layers

Cholesterol

Contains 4 rings and single C-H (carboxyl) chain tail similar to fatty acid

Cholesterol

Precursor of five major classes of steroids

progestins, glucocorticoids, mineralocorticoids, androgens, estrogens

five major classes of steroids

Androgens

male hormones like testosterone

Mineralocorticoids

aldosterone

Glucocorticoids

cortisol

Liver

Cholesterol is synthesized and being produced in the body by what organ?

Cholesterol Ester (70%)

Free Cholesterol (30%)

2 Forms of Cholesterol

Cholesterol Ester

Hydrophilic (polar cholesterol)

Compost of cholesterol ring and a fatty acid

Lecithin-Cholesterol Acyl Transferase (LCAT)

Cholesterol Ester undergoes esterification by?

Lecithin-Cholesterol Acyl Transferase (LCAT)

Catalyzes the esterification of cholesterol by promoting the transfer of fatty acids from lecithin to cholesterol which results in the formation of lysolecithin and cholesterol ester

Free Cholesterol

Unesterified cholesterol; unbound, no other cholesterol attached

Found in the surface of lipoproteins;

Hydrophobic

Cholesterol from Acetyl-COA

Synthesis with more than 25 enzymes

Oxidative decarboxylation of pyruvate to beta-hydroxy beta-methyl glutaryl CoA (HMG-CoA)

Precursor of cholesterol

HMG-CoA reductase

HMG-CoA converted to mevalonic acid by?

HMG-CoA

an enzyme being inhibited by statins

Statins

component of maintenance; medications to inhibit HMG-CoA for the cholesterol levels to decrease

Mevalonic acid

Squalene Cholesterol

Beta oxidation of fatty acids

Conversion of acetyl CoA is derived from?

Beta oxidation of fatty acids

Attachment of fatty acid in acetyl CoA

apolipoprotein

a protein portion of lipoprotein

Lipoproteins

Large macromolecular complexes of lipids

Apoenzyme

a protein portion of an enzyme

transport of TAG and cholesterol to sites of energy storage and utilization

Main purpose of Lipoproteins

Chylomicrons

Main transporter of triglycerides

Very-Low-Density Lipoprotein (VLDL)

Transporter of triglycerides

Intermediate Density Lipoprotein

IDL

Low Density Lipoprotein (LDL)

Major carrier of cholesterol esters;

Delivers cholesterol to all cells or different organs that might need cholesterol as a precursor hormone production

LDL

When it is in excess, it is deposited to different parts of the body

High Density Lipoprotein (HDL)

Carries cholesterol;

Reverse pathway: collects excess cholesterol in the body and will return it back to the liver;

Cardio-protective component or molecule

inversely

LDL and HDL are _________ proportional.

Chylomicrons

Largest and the least dense among LLP;

LLP with lowest density;

Chylomicrons density

Chylomicrons

Transports exogenous TAG

Intestines

Chylomicrons are produced by what organ?

6-9 hours post-prandial

Chylomicrons are completely cleared within?

10 hours fasting

How many hours of fasting is required for lipid profile to standardize?

“Milky” plasma, accumulate as a floating creamy layer when undisturbed for several hours

High levels of CM result in?

Cholesterol

Turbid plasma is due to?

TAG 80-95 (90%)

CHON (1-2%)

Major composition of chylomicrons

apoB-48, apoA-I, apoA-IV, apoC-I, apoC-II, apoC-III, and apoE

The apolipoproteins in CM include?

apoC-II

In metabolism of CMs, it serves as an activator of lipoprotein lipase

Very Low Density Lipoprotein (VLDL)

pre-beta LPP;

supply the tissues of the body with triglycerides of endogenous, primarily hepatic, origin and cholesterol

Liver

VLDL particles are produced by what organ?

50% triglycerides

40% cholesterol and phospholipid

10% protein

VLDL contains?

0\.95-1.006 kg/L

VLDL density

mostly apoB-100 and apoC-I, apoC-II, and apoC-III, but also apoE

VLDL apolipoproteins are?

Low Density Lipoprotein (LDL)

produced through the metabolism of VLDL in circulation and constitutes about 50% of the total lipoprotein mass in human plasma