Question 54 from UPSC CSE 2019 - Science & Technology

Question

With reference to the recent developments in science, which one of the following statements is not correct?

Accepted Answer

Correct Option: A. Functional chromosomes can be created by joining segments of DNA taken from cells of different species.

Strategy: Focus on the feasibility of each statement using recent advances in biotechnology. Statements about artificial DNA synthesis, DNA replication outside cells, and cell division in laboratory conditions all align with well-established biotechnological protocols. However, the creation of functional chromosomes by arbitrary joining of DNA segments from different species is not scientifically valid or demonstrated, as chromosome function depends on precise arrangement and species-specific compatibility. This makes option A the 'not correct' statement.

Key Info: - Functional chromosomes: Natural chromosomes have intricate arrangements of regulatory elements, centromeres, telomeres, and species-specific sequences. While artificial chromosomes (e.g., yeast artificial chromosomes, bacterial artificial chromosomes) are created in host organisms, these utilize compatible DNA and defined sequences rather than random segments from unrelated species. Stable, fully functional chromosomes have not been generated by simply joining DNA from various species, as compatibility constraints prevent normal function and inheritance.
- Artificial DNA synthesis: Laboratory techniques (solid-phase synthesis, PCR) allow for the creation of specific DNA fragments, known as oligonucleotides or synthetic genes, which are then used for research, diagnostics, or engineering.
- DNA replication outside living cells: In vitro DNA replication is routinely performed by techniques like Polymerase Chain Reaction (PCR), allowing DNA fragments extracted from organisms to be copied many times outside of living cells.
- Cell culture and division: Both animal and plant cells can be cultured and induced to divide in controlled laboratory conditions (in vitro), a foundation of tissue culture technology. Such cells can be maintained and studied in petri dishes, facilitating research in developmental biology, medicine, and genetics.

Answer

Option B: Pieces of artificial functional DNA can be created in laboratories.

Answer

Option C: A piece of DNA taken out from an animal cell can be made to replicate outside a living cell in a laboratory.

Answer

Option D: Cells taken out from plants and animals can be made to undergo cell division in laboratory petri dishes.