BIO202 Final Term Notes

BIO202 Final term notes · Regards By Admins: · VU Friends

Q1. Write types of alcohol?

Glycerol and Sphingosine are the two types of alcohols most commonly found in lipids.

1..Glycerol · 2..Sphingosine · 1.Glycerol:

•  It is a simple poly hydroxy alcohol (also called polyol or sugar alcohol) and part of a class of lipids: glycolipids
•  It contains 3 carbons and 3 hydroxyl (OH) groups.
•  Glycerol is synthesized from Dihydroxyacetone Phosphate (an intermediate of the glycolytic pathway
•  Dihydroxyacetone phosphate is acted upon by two enzymes to form glycerol, namely Glycerol Phosphate Dehydrogenase and Glycerol Kinase respectively.
•  Glycerol is a precursor for synthesis of triacylglycerols and of phospholipids in

the liver and adipose tissue.

•  When the body uses stored fat as a source of energy, glycerol and fatty acids are released into the bloodstream And enter the glycolysis pathway directly

2. Sphingosine:

•  Sphingosine is an amino alcohol, which is a component of the class of lipids known as sphingolipids
•  Sphingosine is synthesized in the body in the form of ceramide, to which different moieties are added to form sphingolipids.
•  C Serine and palmitoyl CoA condense to form a product (ketosphinganine) that is reduced.
•  A very long-chain fatty acid forms an amide with the amino group. a double bond is generated, and ceramide is formed.
•  There is no direct route of synthesis from sphinganine (dihydrosphigosine) to

sphingosine; it has to be acylated first to dihydroceramide, which is then dehydrogenated to ceramide.

•  Sphingosine is formed via degradation of sphingolipid in the lysosome. Therefore ceramide is the structural parent of all sphingolipids.
•  In short, Serine+ Palmitate
•  Sphingosine + FA = ceramide

Q2. write Properties of Glycerol?

•  Popularly known as glycerin,
•  Glycerol is widely used in pharmaceutical and cosmetic preparations.
•  It has the following properties:
•  Colorless
•  Viscous oily liquid with
•  sweet taste.

Acrolein Test:

On heating with sulfuric acid or KHSO4 (dehydration) it gives acrolein that has a bad odor. used for detection of free glycerol or any compound containing glycerol. Potassium bisulfate is a potassium acid salt of sulfuric acid, with the molecular formula KHSO 4

• In contrast to glycerol

Sphingosine does not show positive acrolein test. Therefore glycerolipids and shingolipids can be differentiated on the basis of acrolein test. Glycerol combines with three molecules of nitric acid to form Glycerol trinitrate that is used as explosive and vasodilator

Q3. Explain Simple lipids?

Esters of fatty acids with various alcohols These contain: a. Fats (and Oils) and b. Waxes.

a. Fats:

Esters of fatty acids with glycerol (Oils are fats in the liquid state)

b. Waxes:

Esters of fatty acids with higher molecular weight monohydric alcohols. (having one OH group)

Q4. What is Triacylglycerols (TAGs) and its structure?

The simplest lipids constructed from fatty acids are the triacylglycerols, Also referred to as; triglycerides,fats,or neutral fats or storage lipids. Triacylglycerols are composed of three fatty acids in ester linkage with a single glycerol

Structure of triacylglycerols:

•  The three fatty acids esterified to a glycerol molecule are usually not of the same type
•  The fatty acid on carbon 1 is typically saturated,
•  Whereas that on carbon 2 is unsaturated, and that on carbon 3 can be either Simple triglycerides:
•  Fatty acids connected to glycerol are of the same type e.g., tripalmitin.

Mixed triglycerides:

•  Fatty acids are of different types, e.g., stearo-diolein and palmito-oleo- stearin.

 Simple triglycerides:

Fatty acids connected to glycerol are of the same type e.g., tripalmitin.

 Mixed triglycerides:

•  Fatty acids are of different types, e.g., stearo-diolein and palmito-oleo- stearin.
•  The main difference between fats and oils is for oils being liquid at room temperature, whereas, fats are solids.
•  This is mainly due to presence of larger percentage of unsaturated fatty acids in oils than fats that has mostly saturated fatty acids
•  TAGs containing saturated fatty acids are solid at room temperature such as butter whereas