Question

Direction: Read the following statements and answer wrong statements.1. Nitrogenous base is linked to pentose sugar through an N-glycosidic bond.2. Phosphate group is linked to 5'-OH of a pentose sugar through phosphoester bond.3. Two nucleosides are linked through a 3'- 5' N-glycosidic bond.4. Negatively charged DNA is wrapped around positively charged histone octamer to form the nucleosome.5. The chromatin that is more densely packed and stains dark is called euchromatin.

• (A) 1, 2, and 3 are wrong statement
• (B) 4 alone is the wrong statement
• (C) 3 and 5 are wrong statement
• (D) 1 alone is the wrong statement

Answer 1

The Correct Option is C

Explanation:
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.Hence, the correct option is (C).