Department of Biochemistry

Foundation Module Phase - 1

Lipids

Soluble in non-polar solvents and insoluble in polar solvents. Lipids are not polymers

Provide energy

Structural components of biological membranes.

synthesized bile acids that aid

lipid solubilization

Serve as vitamins and hormones.

The lipids of physiological importance for humans have four major functions

                 

What are the health issues associated with lipids?

Classification of lipids

1) Simple lipids-

Give some examples for simple lipids?

2) Complex /Compound lipids-

Fatty acids + Alcohol

Fatty acids + Alcohol+ X

Some common examples for complex lipids

Fatty Acids

Fatty Acids are amphipathic molecules. Why?

What is the chemical difference between saturated and an

unsaturated fatty acid?  

Unsaturated fats are preferred over saturated fatty acids for nutritional reasons.

Would you expect a deep sea fish (living in cold water) or a shallow water fish (living in warmer water) to have

a higher percentage of unsaturated fatty acids in its tissues?

(find the best answer)

A deep sea fish A shallow water fish

corn oil contains 86% polyunsaturated fatty acids

So tend to be liquid at room temperature

Saturated fatty acids (tropical oils, animal fats) tend to be solids, or nearly solids, at room temperatures.

Olive oil contains monounsaturated fatty acids. So tend to be liquids at room temperatures, likely to solidify when refrigerated.

The degree of saturation of a fatty acid affects particularly the fatty acid

melting point.

Why does this occur?

Melting Points and Solubility in Water of Fatty Acids

Solubility in H2O

Chain Length

Melting Point

Effects of Double Bonds on the Melting Points

16:0 

6016:1 118:0 6318:1 1618:2 -518:3 -11

F. A. M. P. (0C)

 M.P.

# Double bonds

What are essential fatty acids?

Name a good source of ‘omega-3 oils’

Oily fish

- salmon, mackerel, sardines,tuna. Pumpkin seeds, sesame seeds soybean oil

Linoleic acid (LA)

It is a component of many commonVegetable oils.

sunflower, soybean, corn and cottonseed oils

Why are essential fatty acids good for you?

I. Saponification Value

. O

C R

O

O

C R

C R

O

H2C O

HC O

H2C O

KOH

H

H

H

H2C O

HC O

H2C O

R C OK+ 3 + 3

What are the main ingredients in your soap?

Soap

• One test tube is filled with Sunflower oil (A). •Coconut oil is placed in a second test tube.(B)• Add few drops of Hubl’s iodine for each solution. • Test tubes are shaken. •After some minutes a spatula full of starch powder is added to each of the two test tubes.

•The test tubes are again shaken.

A B

Comment the observation.

Foods prepared with edible oil develop a kind of smell and undergo changes in taste. What is the reason for this?

Rancidity

Hydrolytic Oxidative

Partial hydrolysis of TAG Oxidation of UFA @double bond positions.

FFA Glycerol

(mono/di) Peroxides

Aldehyde Ketones

Objectionable odour + Taste

Objectionable odour + Taste

Mostly Triacylglycerides:

Fat and oils

O

H2C OH

HC OH

H2C OH

HO C R

HO C R

HO C R

O

O

O

H2C O C RO

O

H2C O C R

HC O C R+ + 3 H2O

Glycerol 3 Fatty Acids Triacylglyceride

What elements are found in lecithin?

What do you know about Sphingolipids?

Identify- a - j

What are Eicosanoids?

leukotrienes phospholipids arachidonate diacylglycerol

prostaglandin H2 prostacyclins thromboxanes

other prostaglandins

Lipoxyganase

PGH2 Synthase

Prostacyclin Synthase

Thromboxane Synthase

Linear pathway

Cyclic pathway B

A

Name the enzymes A& B.

State the mechanisms by which aspirin and ibuprofen inhibit PGH2 Synthesis.

What Is Hydrogenated Vegetable Oil?

Vegetable oils are generally liquid at room temperature, so how is it that we have margarine made from sunflower oil and corn oil?

.

Steroids

•Steroid nucleus

•3 cyclohexane rings

•1 cyclopentane ring

steroid nucleus

Cholesterol

•Most abundant steroid in the body

•Add methyl CH3- groups, alkyl chain, and -OH to steroid nucleus

CH3

HO

CH3

CH3 CH3

CH3

Cholesterol in the Body

•Cellular membranes

•Myelin sheath, brain,

and nerve tissue

•Bile salts

•Hormones

•Vitamin D

Q. Identify each lipid as: (1) phospholipid (2) steroid

(3) triglyceride (4) sphingolipid

A. Cholesterol

B.Glycerol, 2 fatty acids, phosphate, and choline

C.Sphingosine, fatty acid, phosphate, and choline

D.Estradiol

E. Bile salts

F. Most of plasma membranesAnswer

The diagram represents a phospholipid molecule

                                                      

(c) Name the following parts of the molecule

(i) A

(ii) B

(iii) C

Answers

How Does this happen ???????

Back to the QFor more details

(for your interest only)

a.Fats: Fatty acids + Glycerol

b. Waxes: Fatty acids + Long chain alcohol

Back to the q

Example Fatty acids Alcohol other component

a.Phospholipid

ex:1.Glycero phospholipid

ex: Lecithin

2.Sphingophospho lipid

b.Glycolipids(Glycosphingo lipid)

Fatty acids

Fatty acids

Fatty acids

Fatty acids

Fatty acids

Alcohol

Glycerol

Glycerol

Sphingosine

Sphingosine

Phosphoric acid residue

Phosphoric acid residue

Choline

Phosphoric acid residue

Carbohydrate

Back to the q

O

R C OH

#1 Carbon Acid Group O

R C OH

Non-polar End - Hydrophobic End (Fat-soluble tail)

Polar End - Hydrophilic End

Back to the q

             

presence of double bonds

CH3 CH2 CH2 CH2 CH2 CH2 CH2 C OH

O1245678 3

CH3 CH2 CH2 CH2 CH2 CH2 CH2 C OH

O1245678 3

Back to the qPresence of double bonds

A deep sea fish

Back to the q

Double bonds place kinks in hydrocarbon chains

and kinked hydrocarbon chains have lower melting points than not kinked

Back to the q

Essential fatty acids (EFAs)

Are fatty acids that are required in the human diet;

They must be obtained from food as human cells have no biochemical pathways capable of producing them internally.

There are two families of EFAs: ω-3 (or omega-3 or n-3) and ω-6 (omega-6, n-6.) I. Alpha-linolenic acid (ALA) -

is a polyunsaturated omega-3 fatty acid.

II. Linoleic acid (LA) is an unsaturated omega-6 fatty acid.

Back to the q

Essential fatty acids are used by every cell in your body -- and healthy cells make healthy people!

EFAs control or modulate an amazing number of cellular processes. Essential fatty acids regulate a large number of mechanisms including increasing the fluidity of cell membranes and improving the ability of selective permeability.

These mechanisms help keep toxins out and bring nutrients into your cells.

Essential fatty acids also influence the activation of cell genes, act as second messengers and produce good eicosanoids.

Eicosanoids help reduce inflammation in the body, help keep blood from clotting, and help keep your blood vessels dilated.

Furthermore, a diet rich in EFAs can be helpful in many diseases

Back to the q

Discussion and background:

Sunflower oil contains unsaturated fatty acids. Iodine adds across the double bonds in an unsaturated bond. Coconut oil consists mainly of glycerides from saturated fatty acids (e.g. palmitic and lauric acid).

Observation: The sample containing Coconut oil turns intensely blue (iodine-starch complex). In Sunflower oil all the iodine will be consumed. Consequently no color change can be observed after the addition of starch.

Back to the q

Back to the q

Back to q

a: Oligosaccharide b: Glycoprotein c: Glycolipids d: Head of phospholipid e:Tail of phospholipid f: Phospholipid bilayer g: Filament h:Peripheral protein i: Cholesterol j: Transmembrane protein

Back to the q

Eicosanoids are a family of powerful, hormone-like compounds produced in the body from essential fatty acids . . .

•They have specific effects on target cells close to their site of formation. •They are rapidly degraded, so they are not transported to distal sites within the body.

•Examples: prostaglandins, prostacyclins, thromboxanes, leukotrienes, epoxyeicosatrienoic acids (EETs). •Roles in inflammation, fever, regulation of blood pressure, blood clotting, immune system modulation, control of reproductive processes & tissue growth, sleep/wake cycle regulation.

Back to the q

A: LipoxygenaseB:PGH2 synthase

Back to the q

Previous slide

A. 2 steroid

B. phospholipid

C. 4 sphingolipid

D. 2 steroid

E. 2 steroid

F. 1 phospholipid

Back to the q

2 Fatty acidsGlycerolPhosphate group &

N- base

Back to the q