Biomolecules-Lipids | UK-Sir-Notes | Biomolecule-3

 

LIPIDS:

Lipid

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Definition:

·         These are - Fatty acid esters of Alcohol and related substances.

·         Insoluble in water, can be dissolved in nonpolar organic solvents like benzene, chloroform, acetone etc.

·         Made up of C,H,O and other attached group

·         The most common composition of Lipid is Fatty acid (R-COOH) Glycerol (C₃H₈0₃).

·         They can form Emulsion complex i.e. minute droplet uniformly distributed in water.

Fatty Acids:

 

·         Organic acids with Hydrocarbon Chain ends in a carboxyl group.

·         Mostly straight, may be ring structure

·         Length differ from 4-24 carbon

·         Plant can form all type of fatty acids

·         But animal cant form 3 F.A. called essential fatty acid (Linoleic, Linolenic and Arachidonic acid)

·         Fatty acids are of two types:

Saturated Fattyacid

·         Saturated FA: Double bond absent in carbon chain (unbranched)

·         General Formula C_nH_2nO₂

·         Present in Animal tissue - Solid form.

·         Palmitic Acid- CH₃ (CH₂)₁₄ COOH

·         Stearic Acid - CH₃ (CH₂)₁₆ COOH

 

unsaturated-Fatty-acid

·         Unsaturated FA: One or more double bond.

·         General formula is  C_nH_2n-2xO₂

·         Less melting point, most of the plant lipid in the form of oil.

·         Oil of marine fish- Omega 3 fatty acid present- useful for brain 

Example:

Oleic Acid: C₁₈H₃₄O₂

Linoleic acid: C₁₈H₃₂O₂

Linolenic Acid: C₁₈H₃₀O₂

Structure:

  

unsaturated-FA-types

 

 

Classification of Lipid :

These are of three types:

1.      Simple Lipid –Formed by FA and Alcohol

(Fat, Waxes, Cutin, Suberin etc)

2.      Compound/ Conjugated –Additional group present (Phospholipid, Glycolipid, Lipoprotein)

3.      Derived Lipids:- Derivatives of lipid or lipid like chemicals (Sterols, Terpenes etc.)

1. Simple Lipids

 

A) Fats: (Triglycerides)

·         Tri hydric alcohol (Glycerol) + 3 molecules of fatty acids

·         Hydrolysis occurs for the bonding or esterification.

·         Three FA similar-Pure fat

Ex-Tripalmitin, tristearin, triolein etc

·         Dissimilar FA found- Mixed fat

Ex-Butter fat like-Steario oleio palmitin

·         It is in either Hard fat or in Oil form (Low melting point liquid)

·         Ground nut oil, Mustard oil, Sunflower Oil etc

·         Oil with more than one double bond- Poly Unsaturates (PUFA)- Lower blood cholesterol

Structure:

Simple Lipid

 

B) WAXES :

·         Fatty acid ester of long chain monohydric alcohol.

·         Plant wax occur with cuticle-Bloom (grey color)

·         In animal wax glands present

·         Lanolin coat on Animal fur, Cerumen in ear drum

·         Bee wax- in abdominal gland- contain Palmitic acid + mericyl alcohol and Palmitic acid + hexacosonal.

 

Bee Wax

2) Compound Lipid:

 

A) Phospho Lipid:

·         Triglyceride lipid, but one FA is replaced by Phosphate group and additional nitrogenous group.

·         Amphipathic molecule- Hydrophilic polar head and hydrophobic non polar tail.

·         Form lipid bilayer of membrane system.

Structure:

Phospho lipid

 

 

B) Glyco lipid:

·         Addition of sugar or glucose molecule.

·         Common component of Membrane.

·         Spingo-Lipid: (amino alcohol spingosine)

·         Spingo myelins present in nerve.

·         Cerebrosides and gangliosides of brain  - sugar residues help in transport.

  

 

Glycolipid

 

 

 

3) DERIEVED LIPIDS:

 

A) TERPENES:

·         Lipid like hydrocarbon formed by isoprene units(C₅H₈)

isoprene

·         Terpenes commonly form steroids.

·         Essential oil of plants- like Menthol (2-4 isoprene unit.)

·         Gibbrellins, Vit-A,E,K – (4 units)

·         Chl-a phytol tail – (4 units)

·         Carotenoids- (8 units)

B) Steroids:

·         Complex Lipid

·         contain- Hydrogenated Cyclo pentano-per hydro phenan threne ring.

 

general structure

 

·         Major group of steroids are- Sterols, Bile Acids, Gonadal Hormones, Adreno cortical Hormone, etc.

 

·         CHOLESTEROL: (C₂₇H₄₅OH)

cholesterol

·         Common sterol in animals and plants

·         Formed inside liver and combined with FA

·         Insoluble in water – when rise in blood increases blood pressure by deposition inside arteries (atherosclerosis)

·         Form many hormones like progesterone, testosterone etc, which control sex expression in human

·         Form Vitamin D when expose to UV ray

·         Help in absorption of FA

·         Help in plant growth and flowering

·         Diosgenin- steroid- anti fertility properties.

 

 

Function of Lipids:

·         Reserve food in Plant and animal

·         Present in oily seed and can convert to carbohydrate, protect from UV ray, temperature etc.

·         Vitamin- A, D, E, K are fat soluble.

·         In animal cell fat droplets found- adipocytes

·         In animal body- heat insulator and shock absorber

·         Oil use in edible purpose

·         Used in paint industries etc.

That's all about Lipid. Feel free to ask doubts in comment section.. UKsir

Want to Know about Amino acids, Proteins:

https://uksirnotes.blogspot.com/2021/09/Aminoacids-Protein-UK-Sir-Notes.html

Want to Know about Carbohydrates :

https://uksirnotes.blogspot.com/2021/09/Biomolecules-Carbohydrates-uksir.html

Want to Know about Cell cycle- Mitosis- Meiosis:

https://uksirnotes.blogspot.com/2021/09/Cellcycle-Mitosis-Meiosis-uksir.html