Question:
The natural defence mechanism of bacteria occurs for:
The natural defence mechanism of bacteria occurs for:
Show Hint
In molecular cloning, restriction endonucleases are exploited as "molecular scissors" to cut DNA at precise palindromic locations, but their ecological role in nature is strictly anti-viral defense.
Updated On: Jun 19, 2026
- Destruction of bacteria's own DNA during replication.
- Facilitating efficient cloning process.
- Destruction of invading viral DNA.
- Destruction of invading bacterial DNA.
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Concept
Bacteria have evolved complex immune defense mechanisms to protect themselves against foreign genetic invaders, particularly bacteriophages (viruses that infect bacteria).
Step 2: Restriction-Modification (R-M) System
The primary defense mechanism is the Restriction-Modification system, which consists of two key enzymes:
1. Restriction Endonucleases: These enzymes recognize specific, short palindromic sequences in foreign DNA and cut both strands, rendering the invading viral DNA non-functional.
2. Methyltransferases: These enzymes methylate specific bases (adenine or cytosine) within the host bacterium's own restriction sites. This methylation sterically prevents host endonucleases from binding, protecting the bacterium's own DNA from self-destruction.
Step 3: Conclusion
Hence, the natural restriction defense mechanism is intended for the selective destruction of invading viral (bacteriophage) DNA, matching option (C). Final Answer: (C)
Bacteria have evolved complex immune defense mechanisms to protect themselves against foreign genetic invaders, particularly bacteriophages (viruses that infect bacteria).
Step 2: Restriction-Modification (R-M) System
The primary defense mechanism is the Restriction-Modification system, which consists of two key enzymes:
1. Restriction Endonucleases: These enzymes recognize specific, short palindromic sequences in foreign DNA and cut both strands, rendering the invading viral DNA non-functional.
2. Methyltransferases: These enzymes methylate specific bases (adenine or cytosine) within the host bacterium's own restriction sites. This methylation sterically prevents host endonucleases from binding, protecting the bacterium's own DNA from self-destruction.
Step 3: Conclusion
Hence, the natural restriction defense mechanism is intended for the selective destruction of invading viral (bacteriophage) DNA, matching option (C). Final Answer: (C)
Was this answer helpful?
0
0
Top CBSE CLASS XII Biotechnology Questions
- The natural source of enzyme barnase and barstar, a system used to achieve male sterile plant is:
- Severe combined immunodeficiency disease is caused due to the absence of:
- Single nucleotide polymorphisms usually occur in ______________ regions.
- Artificial seeds are produced by encapsulating the somatic embryos at the ______________ stage in a protective coating.
- The peptide hormones and growth factors to promote healthy growth of animal cells in vitro are often derived from:}
View More Questions
Top CBSE CLASS XII Questions
- 2, b, c are in A.P. and the range of determinant $\begin{vmatrix}1&1&1\\ 2&b&c\\ 4&b^{2}&c^{2}\end{vmatrix}$ is [2, 16]. Then find range of c is
- A boy of mass 50 kg is standing at one end of a, boat of length 9 m and mass 400 kg. He runs to the other, end. The distance through which the centre of mass of the boat boy system moves is
- A capillary tube of radius r is dipped inside a large vessel of water. The mass of water raised above water level is M. If the radius of capillary is doubled, the mass of water inside capillary will be
- A circular disc is rotating about its own axis. An external opposing torque 0.02 Nm is applied on the disc by which it comes rest in 5 seconds. The initial angular momentum of disc is
- A circular disc is rotating about its own axis at uniform angular velocity \(\omega.\) The disc is subjected to uniform angular retardation by which its angular velocity is decreased to \(\frac {\omega}{2}\) during 120 rotations. The number of rotations further made by it before coming to rest is
View More Questions