Question

How many main types of nucleic acids are present in the living systems?

• A. 0
• B. 10
• C. 21
• D. 2

Hint:

While some viruses use single-stranded or double-stranded RNA as their primary genetic material, all cellular life forms (Bacteria, Archaea, and Eukaryotes) utilize double-stranded DNA as their permanent genome and single-stranded RNA for protein synthesis.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Nucleic acids are large biopolymers found in all living cells.
They are responsible for storing, transmitting, and expressing genetic information.

Step 3: Detailed Explanation:
There are exactly two main types of nucleic acids present in all living biological systems:
1. Deoxyribonucleic Acid (DNA):
- This double-stranded, helical macromolecule stores the master genetic blueprint of the cell.
- It consists of a deoxyribose sugar-phosphate backbone and nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
- It is located inside the nucleus (as chromosomes) and organelles (mitochondria and chloroplasts) of eukaryotes, and in the nucleoid region of prokaryotes.
2. Ribonucleic Acid (RNA):
- This typically single-stranded molecule translates the genetic code stored in DNA into functional proteins.
- It contains a ribose sugar and uses Uracil (U) instead of Thymine (T) alongside Adenine, Guanine, and Cytosine.
- The three primary functional types of RNA are messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).
No other classes of genetic polymer exist naturally in living biological systems.
Therefore, there are exactly 2 main types of nucleic acids.

Step 4: Final Answer:
The number of main types of nucleic acids in living systems is 2, matching Option (D).