Question

A giant rat is formed in the laboratory, what is the reason?
A) Gene Mutation
B) Gene synthesis
C) Gene manipulation
D) Gene replication

Answer 1

Hint: A giant rat is also known as transgenic rat, where the word transgenic means transfer of genes. Transgenic rats are rats which have foreign DNA.

Complete answer:
Since early ages, scientists have been using genetically modified mice for research on genes and in the medical sector, especially for using them as animal models of human diseases etc. These mice have their genome altered with the help of genetic engineering techniques. Now let's analyse each and every option to find what gene alteration causes the production of a giant rat.

Option A) Gene mutation is the process where a permanent change is brought about in the DNA sequence in the gene. These mutations can be different as they can affect anywhere from a single DNA base pair which is called point mutation, used to cure sickle cell anemia; To large chromosomal changes where it is used to cure some cancers etc. It is done using insertion, deletion, translocation, substitution etc. This cannot cause the production of a giant rat.
Option B) Gene synthesis is the process of synthesizing artificial genes within a laboratory using biological methods. Unlike in the natural method, gene synthesis does not require a template strand. For genes, which nucleotide sequence is known can be chemically synthesized. For genes, which nucleotide sequence is not known can be synthesized by RNA dependent DNA polymerase. This cannot cause the production of giant rats.
Option C) Gene manipulation is the process of directly manipulating an organism's gene where the new DNA can be inserted randomly, or it can be targeted at a specific part of the genome, giving it a desired phenotype. So for the production of a giant rat, growth hormone genes will be directly injected into fertilized embryos and eggs and that will be used for the production of transgenic mice. And this rat will be giant due to the overproduction of growth hormone.
Option D) Gene replication is the process of production of new gene copies using the existing one. It produces 2 identical replicas of the gene that is undergoing replication. It has three steps initiation, elongation and termination. This process is done using DNA polymerase during DNA replication. But the replication is limited to a certain amount as it does not lead to overgrowth.

Hence, the correct answer is option (C)

Note: Gene manipulation uses gene splicing where the recombinant DNA is used to form polymerase chain reaction. The process of gene manipulation includes:
1.Isolate the DNA from the genome of the organism
2.DNA is put in DNA vector
3.The vector is transferred to the host.