Which of the following statements about DNA is are correct 1 DNA is the hereditary material of all l...........

General Science (NDA) Biology

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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 doubled helical with two nucleotide chains which run anti-parallel.

4. DNA is also found in mitochondria.

Select the correct answer using the codes given below

1, 2 and 3

3 and 4

1, 3 and 4

Only 4

Explanation:

DNA is made up of exon and intron regions. Exons are coding region and introns are non-coding region. Only exon part codes for protein synthesis. DNA is the genetic material of all living organisms. Except in few viruses where, RNA acts as a genetic material such as retrovirus (e.g. HIV virus). Here, RNA redirects DNA synthesis by ‘reverse transcription’ process with the help of ‘reverse transcriptase’ enzyme.
Nuclear DNA is a double helix with anti-parallel chains. DNA also present in mitochondria as well as in chloroplast.
Circular DNA present in mitochondria is similar to bacteria which synthesise proteins related to its own function. That is why these organelles are known as ‘semi-autonomous organelles’.