Biomolecules||Part-V||Plus One Biology||Zoology||Chapter-9||NEET Biology||K-TET NS Exam||Nucleotides

 #biostripsmedia# #pratheeshpallath#

In this session Bio Strips Media takes through the important topics of Biomolecules. It is one of the most important and scoring topics in Plus One Biology Exam and NEET Exam. 

 

This lecture covers:

·         Nucleotides

·         Nitrogen bases

·         Pentose sugar

·         Nucleosides

·         Functions of nucleotides

 

The content being discussed in this video will be helpful for those appearing for the Plus One Biology Exam and NEET Biology Exam.

NUCLEOTIDES

Each nucleotide has three components, a nitrogen base, a deoxyribose (pentose) sugar and a phosphate group.

Nitrogenous bases are of two types:

·        Purines (adenine and guanine) and Pyrimidines (cytosine and thymine).

Purines -  heterocyclic nitrogenous compound( 9 membered double rings ). A purine has for nitrogen atoms 1,3 ,7 and 9 positions.

·        Pyrimidines  - Single ring nitrogenous compounds( six membered single ring) a pyrimidine has two nitrogen atoms at one and three positions.

A nitrogenous base is linked to the pentose sugar through a N-glycosidic bond to form a nucleoside. When a phosphate group is attached to 5'’OH of a nucleoside through phospho-ester linkage, a corresponding nucleotide is formed. Two nucleotides are linked through 3'’-5'’ phospho-diester linkage to form a di-nucleotide and when many nucleotides are linked in this manner, a polynucleotide is formed.

The polynucleotide chain has at the 5'’ end of the sugar a free phosphate moiety (it is called 5'’-end) and at the 3'’-end an OH group (it is called 3'’-end).

The backbone of the polynucleotide is formed by the sugar and the phosphates, while the nitrogen bases project from the back bone.