1. Tardigrade
  2. Question
  3. Biology
  4. Read the following statements and choose the correct option. i. Nitrogenous base is linked to the pentose sugar through a N-glycosidic linkage ii. Phosphate group is linked to 5’-OH of a nucleoside through phosphoester linkage iii. Two nucleosides are linked through 3’- 5’ N-glycosidic linkage iv. Negatively charged DNA is wrapped around positively charged histone octamer to form nucleosome v. The chromatin that is more densely packed and stains dark are called euchromatin

Q. Read the following statements and choose the correct option.
i. Nitrogenous base is linked to the pentose sugar through a N-glycosidic linkage
ii. Phosphate group is linked to 5’-OH of a nucleoside through phosphoester linkage
iii. Two nucleosides are linked through 3’- 5’ N-glycosidic linkage
iv. Negatively charged DNA is wrapped around positively charged histone octamer to form nucleosome
v. The chromatin that is more densely packed and stains dark are called euchromatin

 3968  191 KEAMKEAM 2012Molecular Basis of Inheritance Report Error

Solution:

Two nucleosides are linked through 1 - 4 glycosidic linkage where the bond is normally formed between the carbon 1 of one sugar and carbon 4 of other sugar. Chromatin is a substance of which eukaryotic chromosomes are composed. It consists of proteins (principally histones), DNA and small amounts of RNA. The DNA molecule is wrapped around the histones to form a series of linked globular nucleosomes, resembling beads on a string. This is itself coiled to form a highly condensed solenoid arrangement, constituting a form of chromatin called heterochromatin, which stains densely with basic stains. The genes in the solenoid can only be transcribed if the solenoid unfolds to some extent, forming an expanded chromatin (euchromatin), which is lighter staining.