Which of the following statements about DNA is/are correct ?
- 1. DNA is the hereditary material of all living organisms.
- 2. All segments of DNA code for synthesis of proteins.
- 3. Nuclear DNA is double helical with two nucleotide chains which run anti-parallel.
- 4. DNA is also found in mitochondria.
Select the correct answer using the code given below :
1, 2 and 3 only
3 and 4 only
1, 3 and 4 only
4 only
Answer is Wrong!
Answer is Right!
This question was previously asked in
UPSC NDA-1 – 2016
1. DNA is the hereditary material of all living organisms. This is incorrect. While DNA is the hereditary material for most organisms (bacteria, archaea, eukaryotes), some viruses use RNA as their genetic material.
2. All segments of DNA code for synthesis of proteins. This is incorrect. Large portions of DNA in eukaryotic genomes are non-coding. This includes regulatory sequences, introns (non-coding regions within genes), repetitive DNA, telomeres, etc.
3. Nuclear DNA is double helical with two nucleotide chains which run anti-parallel. This is correct. The Watson-Crick model describes DNA as a double helix where the two polynucleotide strands are complementary and run in opposite directions (5′ to 3′ and 3′ to 5′).
4. DNA is also found in mitochondria. This is correct. Mitochondria (and chloroplasts in plants) contain their own circular DNA (mtDNA), which is distinct from the nuclear DNA.
Based on the analysis, statements 3 and 4 are correct.
– Not all DNA sequences are protein-coding.
– Nuclear DNA is a double helix with anti-parallel strands.
– Extranuclear DNA exists in organelles like mitochondria and chloroplasts.