Genetic Engineering And Biotechnology

Hugo de Vries observed sudden heritable changes (mutations) while working with the evening primrose plant (\textit{Oenothera lamarckiana}). His mutation theory proposed that these sudden changes serve as the basis for evolution, introducing new traits into populations.

It is caused by a point mutation in the βglobin gene, where glutamic acid is replaced by valine at the sixth position of the haemoglobin protein. The mutated haemoglobin (HbS) polymerizes under low oxygen conditions, leading to cell deformation.

Step 1: Recall the Human Genome Project.
Chromosome 1 was the last human chromosome to be fully sequenced due to its size and complexity. It contains the largest number of genes and a high number of repetitive sequences, making sequencing particularly challenging.
Final Answer: The last chromosome to be completely sequenced was Chromosome 1.

Step 1: Analyze the Pedigree Chart.
Both males and females are affected, indicating autosomal inheritance.
The disorder appears in siblings but not in the parents, which is characteristic of a recessive trait.
Final Answer: The genetic disorder depicted is autosomal recessive.

- Down’s syndrome is caused by trisomy of chromosome 21.
- It is characterized by distinct physical features such as short stature, small head, furrowed tongue, and cognitive impairment.

Step 1: Analyzing the given statements:
- Statement (A): "The polymerase enzyme joins the gene of interest and the vector DNA."
This is incorrect. While polymerase enzymes (e.g., Taq polymerase in PCR) are crucial for DNA replication, they do not join the gene of interest and the vector DNA. This is typically done by DNA ligase, not polymerase.
- Statement (B): "Gel electrophoresis is used for amplification of a DNA segment."
This is incorrect. Gel electrophoresis is used to separate DNA fragments based on their size, not to amplify them. PCR (Polymerase Chain Reaction) is used to amplify DNA segments.
- Statement (C): "PCR is used for isolation and separation of the gene of interest."
This is incorrect. PCR amplifies specific DNA segments, but it does not isolate or separate genes. Gel electrophoresis is used for separation, and other techniques like restriction enzymes are used for isolation.
- Statement (D): "Plasmid DNA acts as a vector to transfer the piece of DNA attached to it."
This is correct. In genetic engineering, plasmid DNA is commonly used as a vector to carry and transfer the gene of interest into a host cell.
Step 2: Conclusion:
The correct statement is option (D), where plasmid DNA acts as a vector to transfer the DNA into a host organism for further study or use.