Which of the Following Is NOT a Component of DNA? | NEET Biology
Which of the Following Is Not a Component of DNA?
Question: Which of the following is not a component of DNA?
Answer
DNA, or deoxyribonucleic acid, is a nucleic acid made up of repeating units called nucleotides. Each DNA nucleotide contains a deoxyribose sugar, a phosphate group, and one nitrogenous base.
Components of DNA
DNA contains four nitrogenous bases:
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
The sugar present in DNA is deoxyribose, and nucleotides are linked together by phosphodiester bonds to form the polynucleotide chain.
Why Is Uracil Not a Component of DNA?
Uracil is a nitrogenous base normally found in RNA instead of thymine. RNA contains adenine, uracil, guanine, and cytosine.
| DNA | RNA |
|---|---|
| Adenine (A) | Adenine (A) |
| Thymine (T) | Uracil (U) |
| Guanine (G) | Guanine (G) |
| Cytosine (C) | Cytosine (C) |
DNA vs RNA: Quick Comparison
- DNA sugar: Deoxyribose
- RNA sugar: Ribose
- DNA-specific base: Thymine
- RNA-specific base: Uracil
Frequently Asked Questions
Which nitrogenous base is absent in DNA?
Uracil is absent as a standard nitrogenous base in DNA.
Which base replaces thymine in RNA?
Uracil replaces thymine in RNA.
What are the four bases present in DNA?
The four bases are adenine, thymine, guanine and cytosine.
Quick Revision
DNA → A + T + G + C
RNA → A + U + G + C
Conclusion
Uracil is not a normal component of DNA. DNA contains adenine, thymine, guanine and cytosine, whereas RNA contains uracil instead of thymine.
