TRIACYLGLYCEROLS

• TRIACYLGLYCEROLS

Triester of glycerol with three ester groups

Esterification of three fatty acids to glycerol

Two or three different fatty acids are present

Hydrocarbon chains: hydrophobic characteristic

Ester groups: buried within a nonpolar environment = water insolubility of triglycerides

Functions of triacylglycerol

Energy storage

are concentrated primarily in special cells called adipocytes

SIMPLE triacylglycerol

Three identical FAs

Rarely occurs naturally

MIXED triacylglycerol

More than one kind of FA

Common in nature

Varies depending on food being consumed

HYDROLYSIS

Reverse of the esterification reaction by which it was formed

Occurs during digestion

Esterification

OH groups react with COOH group to form ester bond

By product: H2O

Acidic

Glycerol and fatty acids

Basic

Glycerol and fatty acid salts

PARTIAL HYDROLYSIS

Glycerol

Three Fatty Acids

COMPLETE HYDROLYSIS

Monoacylglycerol

Two Fatty Acids

HYDROGENATION

Produces the solid shortening in stores

Source of trans fatty acids

Margarine undergoes partial hydrogenation

Unsaturated → saturated

Hardening

Hydrogenation in the body

SAPONIFICATION

Oldest known chemical reaction

Base-promoted hydrolysis of fats and oils in aqueous NaOH

soaps

saponification produces glycerol and a mixture of fatty acid sodium salts called

MICELLE FORMATION AND SOAP CLEANSING

Structure of soaps allow fats and oils to break away and dissolve in water

Ball-like structure

Scrubbing dislodges the grease from the surface and soap ions attach themselves

FATTY ACIDS Saturated

Lauric Acid

Myristic Acid

Palmitic Acid

Stearic Acid

FATTY ACIDS Unsaturated

Oleic Acid

Linoleic Acid

Linolenic Acid

FLUID MOSAIC MODEL

Mosaic

Fluid

Polar compounds are transported via active transport

Complex lipids form membrane around the body cells and around small structures inside the cells

Complex Lipids

Constitute the main components of membrane

Simple lipids

Triacylglycerol, diacylglycerol, monoacylglycerol, waxes

Complex lipids

Phospholipid, sphingolipids, cerebroside

Phospholipids

Contain an alcohol, two fatty acids and a phosphate

GLYCEROPHOSPHOLIPIDS

Also called phosphoglycerides

the alcohol is glycerol

polar

Second most abundant group of naturally occurring lipids

LECITHIN

If the other alcohol is choline, it is called phosphatidylcholine

Has stearic acid on one end and linoleic acid in the middle

Major component of egg yolk

Excellent emulsifier

CEPHALIN

Similar to lecithin but different alcohol is involved

They contain alcohols such as ethanolamine or serine

o Involved in blood coagulation

o Found in the heart, liver, and brain

o Sourced from egg yolks

PHOSPHATIDYLINOSITOL

The alcohol inositol is bonded to the rest of the molecule by a phosphate ester bond

Serve as signaling molecules in chemical communication

SPHINGOLIPIDS

Myelin, the coating of nerve axons, contains a different kind of complex lipid

Alcohol portion is sphingosine

Sphingophospholipids

Based on 18-carbon monounsaturated aminodialcohol sphingosine

Saponifiable

Sphingoglycolipids

Simplest are cerebrosides

CERAMIDE

Combination of fatty acid and sphingosine

Many are also found in cerebrosides

Ceramides contain different fatty acids

Stearic acid

occurs mainly in sphingomyelin

GLYCOLIPIDS

Contains carbohydrates and ceramides

Maintain cell membrane stability

Tighten and minimize the look for sagging pores and rough bumps

CEREBROSIDES

Ceramide mono-or oligosaccharides

Named by adding gluco/galacto- depending on the carbohydrate unit attached to it

GANGLIOSIDES

Complex sphingoglycolipids that contain branched chains of up to seven monosaccharide residues.

Occur in the gray matter of the brain and myelin sheath

Considered as possible therapeutics for neurodegenerative disorders

Sphingomyelin

most important lipids in the myelin sheaths of nerve cells and are associated with diseases such as multiple sclerosis.

STEROIDS

A group of plant and animal lipids that contains this tetracyclic ring structure

CHOLESTEROL

the most abundant steroid in the human body, and also the most important

It is a component in plasma membranes in all animal cells.

It is the precursor of all steroid hormones and bile acids

Assist in the synthesis of human tissue, bile production, and fat-soluble vitamins

STEROID HORMONES

Cholesterol is first converted into progesterone and then to both sex hormones and adrenocorticoid hormones

LIPOPROTEINS

Carrier of cholesterols

they contain a core of hydrophobic lipid molecules surrounded by a shell of hydrophilic molecules such as proteins and phospholipids.

High-density lipoprotein (HDL)

Good cholesterol

33% protein and 30% cholesterol.

Low-density lipoprotein (LDL)

Bad cholesterol

25% protein and 50% cholesterol.

Very-low density lipoprotein (VLDL)

Carries triglycerides (fats)

synthesized by the liver

Chylomicrons

Carry dietary lipids synthesized in the intestines

Familial Hypercholesterolemia

Insufficient LDL receptors

Plasma levels of cholesterol rise to 680 mg/100 mL

FEMALE SEX HORMONES

Synthesized in the ovaries from progesterone

Responsible for the development of female secondary sex characteristics and control of the menstrual cycle

MINERALOCORTICOIDS

Control the balance of Na and K ions in the cell

GLUCOCORTICOIDS

Synthesized in the adrenal cortex

Regulates carbohydrate metabolism

Decreases inflammation

Involved in the reaction to stress ( cortisol )

BILE SALTS

Oxidation products of cholesterol

Synthesized in the liver and stored in

Intestine

PROSTAGLANDINS

Family of compounds that have 20-carbon skeleton of prostanoic acid

Formed as a response to physiological triggers

Made at sites of tissues damage or infection that are involved in dealing with injury and illness

They control processes such as inflammation, blood flow, the formation of blood clots and the induction of labor

COX-1

Catalyze normal physiologic

COX-2

Responsible for the production of prostaglandins during inflammation

THROMBOXANE

Derived from arachidonic acid

Induces platelet aggregation and vasoconstriction

Can be inhibited by aspirin and NSAIDs

LEUKOTRIENES

Derived from arachidonic acid

Mainly occur in leukocytes

Produce muscle contractions in the lungs