Ncert Exercises & Solutions

14.24: Write the important structural and functional differences between DNA and RNA.

The structural differences between DNA and RNA are as follows:

	DNA		RNA
1	The sugar moiety in DNA molecules is β-D-2 deoxyribose.	1	The sugar moiety in RNA molecules is β-D-ribose.
2	DNA contains uracil (U). It does not contain thymine (T)	2	RNA contains thymine (T). It does not contain uracil (U).
3	The helical structure of DNA is double-stranded	3	The helical structure of RNA is single-stranded.

The functional differences between DNA and RNA are as follows:

The structural differences between DNA and RNA are as follows:

	DNA		RNA
1	The sugar moiety in DNA molecules is β-D-2 deoxyribose.	1	The sugar moiety in RNA molecules is β-D-ribose.
2	DNA contains uracil (U). It does not contain thymine (T)	2	RNA contains thymine (T). It does not contain uracil (U).
3	The helical structure of DNA is double-stranded	3	The helical structure of RNA is single-stranded.

The functional differences between DNA and RNA are as follows:

	DNA		RNA
1	DNA is the chemical basis of heredity.	1	RNA is not responsible for heredity.
2	Proteins are synthesised by RNA molecules in the cells.	2	DNA molecules do not synthesise proteins, but transfer coded message for the synthesis of proteins in the cells.

What are the different types of RNA found in the cell?

(i) Messenger RNA (m-RNA)

(ii) Ribosomal RNA (r-RNA)

(iii) Transfer RNA (t-RNA)