Correct option is C
Let’s analyze each statement and its matching option:
Statement A: A plasmid cloning vector digested with an enzyme (with a single restriction site in the plasmid) that generates 3' overhangs can be made blunt-ended using ______.
Correct Answer: Mung bean nuclease (from Option 3).
Explanation: Mung bean nuclease is an enzyme that can remove 3' overhangs, generating blunt-ended DNA fragments suitable for cloning. This enzyme can be used to blunt-end DNA that has 3' overhangs following restriction digestion.
Statement B: DNA with a nucleotide composition of 30% A, 35% G, 20% C, and 15% T is most likely ______.
Correct Answer: single-stranded (from Option 3).
Explanation: The provided nucleotide composition of DNA (30% A, 35% G, 20% C, 15% T) suggests a higher proportion of guanine (G), which is typical of single-stranded DNA. The nucleotide composition is more often seen in single-stranded forms due to the proportion of GC content.
Statement C: Production of only truncated molecules of transgene-derived mRNA in transgenic plants generated using a transgene from a prokaryotic source is most likely due to ______.
Correct Answer: presence of potential poly-adenylation signals in the transgene sequence (from Option 3).
Explanation: In prokaryotic systems, mRNA often lacks proper poly-adenylation, a feature required for the stability and full-length production of mRNA in eukaryotes. Without this signal, the mRNA produced in plants from a prokaryotic transgene might be truncated due to the lack of appropriate poly-adenylation, which is necessary for processing and stability.
Statement D: ______ is a method for identifying the positions where individual DNA-binding proteins attach to a genome.
Correct Answer: ChIP-seq (from Option 3).
Explanation: ChIP-seq (Chromatin Immunoprecipitation sequencing) is a widely used method to identify the binding sites of DNA-binding proteins across the genome. This technique allows researchers to map protein-DNA interactions.
Final Answer: Option 3. A – Mung bean nuclease; B – single-stranded; C – presence of potential poly-adenylation signals in the transgene sequence; D – ChIP-seq
Information Booster:
Mung bean nuclease: This enzyme is used for generating blunt-ended DNA by removing 3' overhangs. It is helpful in preparing DNA fragments for cloning or other applications requiring blunt ends.
ChIP-seq: A powerful technique used to study protein-DNA interactions, where DNA is cross-linked to proteins, sheared, and immunoprecipitated with antibodies against the protein of interest. The enriched DNA is then sequenced to identify binding sites.
Poly-adenylation: In eukaryotic cells, poly-adenylation is essential for the stability and processing of mRNA. Prokaryotic genes lack poly-adenylation signals, which can cause premature termination of mRNA in transgenic plants expressing such genes.
