Lipids are water-insoluble biomolecules with functions including cell membrane structure, energy storage, and protection. They are categorized into complex and simple lipids, with triglycerides being the most abundant storage form. Biological membranes consist mainly of lipids and proteins, following the fluid mosaic model, and transport mechanisms include passive diffusion, facilitated diffusion, and active transport.

1. Lipids

2. Definition
• Lipids are water insoluble biomolecules that
can be extracted from cells, tssues by non-
polar solvents. For example : benzene,
Chloroform, Ether

3. Functions
• Structural component of cell membrane .
• Storage form of metabolic fuel.
• Protecting coating on surface on many
microorganisms.
• On some fruits e.g, apple, bird feather
• Cell recognition, species specificity
• Some have biological property as vitamins and
hormones

4. Classification; Presence of FA
• Complex (Saponifiable) lipid
• Simple ( Non saponifiable)
• Complex:
• Lipid Backbone
• 1.Acyl Glycerol Glycerol
• 2. Phosphoglycerides Glycerol 3 PO4
• 3.Sphingolipid Sphingosine
• 4.Waxes Non polar alcohal of high mol. wt

5. Simple lipid
• Terpenes
• Steroids
• Prostaglandin

6. Fatty acids
• Occur largely in large amount in saponifiable
lipids. Only traces are present in free form
• Hydrocarbon chain (C4 to C36)
• Terminal carboxylic group (COOH)
• Saturated FA Palmitic acid , C16, Stearic C18
• Un saturated fA Oleic, C18:1.^9
• Monoenoic : single double bond
• Polyenoic : More than one double bonds

7. • Unsaturated FA predominates over Saturated
FA,, particularly in higher plants & animals
living in low temp.

8. Some naturally occuring fatty acids

9. Packing of fatty acid

10. Essential fatty acids
• Linoleic
• Linolinic
• Arachidonic

11. Omega fatty acids

12. Classification of lipids :Complex :
Neutral Fat/ Triacyl Glycerol /
Triglycerides
• Triacylglycerols Are Fatty Acid Esters of Glycerol
The simplest lipids constructed from fatty acids are the
triacylglycerols, also referred to as triglycerides, fats,or neutral fats.
• Triacylglycerols are composed of three fatty acids each in ester
linkage with a single glycerol
• Those containing the same kind of fatty acid in all three positions
are called simple triacylglycerols and are named after the fatty acid
they contain. Simple triacylglycerols of 16:0, 18:0, and 18:1, for
example, are tristearin, tripalmitin, and triolein, respectively.
• Most naturally occurring triacylglycerols are mixed
;

13. • Fatty acid ester of glycerol are called acyl glycerol or
Glycerides.
• Most abundant family of lipid.
• Major component of storage lipid.
• It provides stored energy and insulation
• Triacylglycerol which are solid at room temperature is
called fat. Fat has higher mp than oil
• Which are liquid are called oil. In oil, m.p is lower than
fat.
• 1 gm fat gives 9 K cal against 4K cal from
carbohydrates.

14. Triglyceride

15. Phosphoglycerides
• Second largest class of complex lipid
• Major component of cell membrane.
• In phospho glycerides,one of the primary
hydroxyl group of glycerol is esterified with
phosphoric acid and others are esterified with
fatty acids.

16. :

19. Common phospholipids
• Phosphotidyl-ethanolamine (Cephalin)
• Phoshatidyl choline (Lecithin)

20. Sphingolipids
• Second largest class of membrane lipid in
plants and animals.
• Present in brain and nerve tissues in large
amount.
• have one polar head group and two non
polar tails.
• but they donot contain glycerol

21. • Shingolipids are composed of :
• Sphingosine : Long chain amino alcohal or its
derivatives
• One molecule of long chain FA
• A polar head that is joined by glycosidic
linkage or phosho diester linkage

24. Waxes
• Ester of long chain (C14 –C36) saturated and
unsaturated fatty acids with lonf chain (c16 –
C30) alcohal.
• They are chief storage form of metabolic fuel
of free floating marine organism.
• Due to water repellent property, they protect
the bird feather, leaves ,fruits,. Apple has waxy
coating

25. Bee wax component

26. Simple lipids
• They donot contain fatty acids as component.
• Terpenes and steroids are important group of
compounds.
• They are made up of 5C isoprene unit.
• Biological active counterpart is Isopentylpyro
phosphate.

27. Terpenes
• Terpenes containing
• 2 isoprene units -- monoterpenes
• 4 Diterpenes
• 6 Triterpenes
• Many Poly terpenes
• 3 Sesquiterpene
• Terpenes may be linear or cyclic molecules

28. • The characterstic aroma/flavour of essential
oil is due to terpenes
• cumin, coriander, fennel, mentha.
• Large number of terpenes are derived from
plants.
• Limonene (lemon oil)
• Anethole (fennel)

29. Steroids
• Are simple lipids. They are derived from
isoprene units. All steroids are originated
from linear triterpene, Squalene which
cyclises readily.
• The first important product of this cyclization
is lanosterol.
• which is precursor of cholesterol.
• Cholestrol (Vertebrates)
• Ergosterol (Fungi)

30. • Cholesterol is insoluble in water., but readily
extractable from tissues using chloroform,
ether, benzene.
• Cholesterol is precursor of many
steroids,including bile acids( emulsify and
absorb lipids)
• Androgen , Esterogen , Adrenocorticone

31. Prostaglandin
• Physiologically active lipid compound.
• Family of FA derivatives which have variety of
biological activities.
• They are synthesized from Archidonic acid.
• They have diverse hormone like effects .
• PG are found in prostrate gland,seminal
plasma and seminal vesicle.

32. • Lower blood pressure
• Stimulate contraction of smooth muscle.
• PG E1, PGF1.
• The name of prostaglandin was given by Von
Euler.

33. Biological membranes and transport
• Plasma membrane is an envelop which
surrounds the cell.
• It separates and protect the cell from
environment.
• It is connecting system between cell and
environment.
• The subcellular orgeneles such as
mitochondria, nucleus, lysosomes are
surrounded bymembrane.

34. Chemical composition
• The membrane is composed of mainly lipid
and protein.
• The actual composition differ from tissue to
tissue.
• Among lipid,amphipathic lipids
namely,phospholipid and glycolipid &
cholesterol are found in animal membrane.

35. Structure of membrane
• Fluid mosaic model given by Singer and
Nicholson.
• Essentially composed oflipid bilayer.
• The lipid hydrophobic region face each other
at the core of bilayer while the hydrophilic
(polar) region faces outward.
• Globular proteins are irregularly embedded in
the lipid bilayer. They are catagorized into two
groups.

36. • Extrinsic (Peripheral) membrane proteins
• Are loosely held to the surface of membrane.
• They can be easily separated e.g. CytochromeC
• Intrinsic (Integral) proteins
• Tightly bound to lipid bilayer. Separated by
• Detergent, organic solvent.
• E.g. Hormone receptor

37. Fluid mosaic model

38. Transport across the membrane
• Biological membranes are relatively
impermeable.
• They form a barrier for the free passage of
compounds across it.
• Three mechanism for transport of solutes.
• Passive diffusion
• Facilitated diffusion’
• Active transport

39. Passive diffusion
• It is a simple process which depends on the
concentration gradient of a particular
substances across the membrane.
• This process does not require energy.
• There is a difference in concentration of
solutes between two areas.

40. Facilitated diffusion
• is comparable to diffusion.
• Since solutes move along the concentration
gradient ( from higher to lower concentration
)
• No energy is needed .
• Carrier or transport protein is required .
• Specific carrier proteins for the transport of
Gal, Glu, Leu, Phe, have been isolated &
characterized.

41. Active transport
• It occurs against concentration gradient.
• It requires energy. Eg Na K pump
• Cell have high intracellular K+
• Low Na+
• Na+K+ pump is responsible for maintaining
high K+ and lowNa+ in the cell.

43. Transport System
• Uniport system : This involves the movement
of single molecule through membrane,
• E.g. Transport of glucose to erythrocyte
• Symport : Simultaneous transport of two
different molecules in the same direction e.g.
Transport of Na+ and glucose to the intestinal
mucosa

44. • Antiport :
• Simultaneous transport of two molecules in
opposite direction.e.g. Exchange of Cl & HCO3
in erythrocyte.