NEET 2023 Botany Question 135 Solution
Question
In gene gun method used to introduce alien DNA into host cells, microparticles of metal are used.
- (1)Silver
- (2)Copper
- (3)Zinc
- (4)Tungsten or gold
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In gene gun method used to introduce alien DNA into host cells, microparticles of metal are used.
In the biolistics/gene gun method for plant transformation, microscopic beads of dense, biologically inert Gold (Au) or Tungsten (W) are coated with recombinant DNA and accelerated at high velocity into target plant cells!
Plant cells possess thick, cellulose-rich walls that resist chemical transformation (such as heat shock). The biolistic method achieves direct physical penetration by bombarding target cells with high-momentum microprojectiles:
NCERT states verbatim: "In a method known as biolistics or gene gun, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA."
Silver, copper, and zinc are cytotoxic heavy metals that induce oxidative stress and cell death. Gold and tungsten are biochemically inert and high-density, making them ideal carriers.
Diagnose every choice: Know exactly why the right option works and why distractors fail.
Silver () ions are bactericidal and phytotoxic; silver is never used as a biolistic microcarrier.
Copper () induces severe heavy-metal toxicity and DNA damage.
Zinc () lacks the necessary density and chemical inertness required for microparticle ballistics.
Verbatim NCERT: microparticles of tungsten or gold are used in biolistics/gene gun delivery.
Students frequently confuse host targets: Microinjection is used primarily for animal cells (injecting into the nucleus directly), whereas Gene Gun / Biolistics is used primarily for plant cells.
"In another method, suitable for plants, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA in a method known as biolistics or gene gun."
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