Q.37 Given below are two statements:
Statement I: Transduction is virus-mediated bacterial DNA-recombination.
Statement II: Transduction is also used for bacterial gene linkage and gene mapping studies.
In the light of the above statements, choose the
correct answer from the options given below:
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is true but Statement II is false
- Statement I is false but Statement II is true
Both Statement I and Statement II are true. Transduction involves bacteriophages transferring bacterial DNA, enabling recombination, and serves as a key method for mapping genes via linkage analysis.
Understanding Transduction
Transduction is a process where viruses called bacteriophages accidentally package bacterial DNA from one bacterium and deliver it to another during infection. This leads to genetic recombination without direct cell contact, distinguishing it from conjugation or transformation. Statement I accurately describes this virus-mediated mechanism.
Evaluating Statements
Statement I: True. Bacteriophages either generalize (any DNA segment) or specialize (specific genes near prophage sites) to transfer donor DNA, which recombines with the recipient’s homologous regions via enzymes like RecA.
Statement II: True. In transduction experiments, co-transduction frequency of nearby markers reveals linkage distances, aiding fine-scale bacterial gene mapping, as pioneered by researchers like Zinder and Lederberg.
Option Analysis
Option Explanation Both true Correct; both statements match established definitions and applications . Both false Incorrect; transduction definitions confirm Statement I, and genetic studies validate II . I true, II false Incorrect; mapping via transduction is a standard technique . I false, II false Incorrect; core mechanism is virus-based DNA transfer . Introduction to Transduction Virus-Mediated Bacterial DNA Recombination
Bacterial transduction represents a pivotal virus-mediated bacterial DNA recombination process where bacteriophages transfer genetic material between bacteria. Discovered by Zinder and Lederberg, it enables transduction bacterial gene linkage and gene mapping studies without cell-to-cell contact. Ideal for competitive exams like GATE/NEET, understanding transduction clarifies genetic recombination mechanisms.
Types of Bacterial Transduction
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Generalized Transduction: Phage mistakenly packages random bacterial DNA during lytic cycle, injecting it into new hosts for potential recombination.
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Specialized Transduction: Temperate phages excise with adjacent bacterial genes from lysogenic state, transferring specific loci.
Mechanism and Steps
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Phage infects donor bacterium.
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Viral replication packages bacterial DNA.
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Transducing phage infects recipient, inserting donor DNA for homologous recombination.
This process underpins bacterial gene mapping by measuring co-transduction frequencies inversely proportional to gene distance.
Applications in Gene Linkage Studies
Transduction excels in gene mapping studies due to high resolution for closely linked genes. Hershey-Chase used it to prove DNA as genetic material; modern uses include genetic engineering and mapping bacterial chromosomes.
For Life Sciences students, questions like “Transduction is virus-mediated bacterial DNA-recombination” test these concepts directly.
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