Question

Question 2 

Each nucleotide consists of: 

• A pentose sugar, a nitrogenous base and a phosphate group 

• A pentose sugar and a nitrogenous base 

• A nitrogenous base and a phosphate group 

• A pentose sugar and a phosphate group Incorrect 

Question 3 

In a single polynucleotide strand, the individual nucleotides are covalently linked together by bonds between the _______ 

Answer 1

Answer2: option 1 is correct answer.

A nucleotide is a building block of the backbone of DNA. It is made up of a pentose sugar, nitrogenous base ( A or T or G or C) and a phosphate.

So NULEOTIDE= Pentose sugar + Nitrogenous base + phosphate.

Also, NUCLEOSIDE = Pentose sugar+ Nitrogenous base

Hence we can also say that:

NUCLEOTIDE = Nucleoside + phosphate group

Answer3: option 1 is correct.

In a single polynucleotide strand, the individual nucleotides are covalently linked together by bonds between the sugars.

The entire backbone of DNA is formed by the bond between nucleotides. Precisely in a single polynucleotide strand, a covent bond is formed between a sugar of a nucleotide joined by a phosphate group attached to sugar of another nucleotide. In this way, an alternative sugar-phosphate-sugar bond exist all along the polynucleotide chain.

So we can say that an individual nucleotide is covalently joined by a phosphodiester bond between sugars. Hence, option 1 is the correct answer.