Question

Match List I (structure) with list II (explanation/definition) and select the correct answer.

List-I	List-II
a. Nucleoside	$1$. Deeply stained body containing rRNA
b. Nucleotide	$2$. Portion of a DNA or RNA composed of one deoxyribose(in DNA) or ribose(in RNA) plus a purine or a pyramidine
c. Nucleolus	$3$. Short disk-shaped cylinders composed of nucleoproteins and spaced at roughly $100$A intervals on chromosomes
d. Nucleosome	$4$. Portion of DNA or RNA composed of a purine or pyramidine base, a deoxyribose (in DNA) or a ribose (in RNA) and phosphoric acid

• A. A-$1$, B-$3$, C-$2$, D-$4$
• B. A-$2$, B-$1$, C-$3$, D-$4$
• C. A-$1$, B-$3$, C-$4$, D-$3$
• D. A-$2$, B-$4$, C-$3$, D-$1$

Answer 1

The correct option is D A-$2$, B-$4$, C-$3$, D-$1$

Nucleosides are a structural subunit of nucleic acids, the heredity-controlling components of all living cells, consisting of a molecule of sugar linked to a nitrogen containing organic ring compound. There are nitrogenous base, usually either a purine or pyrimidine and a five carbon carbohydrate ribose.

Nucleotides are composed of a simple nucleoside with addition of phosphate groups or group. There are 4 nucleotide named as A(adenine),C(cytosine),T(thymine),G(guanine). This are the monomers of the nucleotide.

Nucleolus is the distinct structure present in the nucleus of eukaryotic cells. It is composed of RNA and proteins which form around specific chromosomal regions.

Nucleosome is formed when DNA wrap around histone octamer. Each nucleosome contains 'beads-on-string' under electron microscope.

So, the correct option is 'D'.