Gene therapy was first attempted in 1990 on a patient suffering from the deficiency of which enzyme?
- A.Adenosine deaminase
- B.Amylase
- C.Lipase
- D.Trypsin
Correct answer
Explanation
The correct answer is A, adenosine deaminase. The deficiency of adenosine deaminase destroys the immune system because the enzyme is needed for the normal working of lymphocytes, and in 1990 lymphocytes of a girl with this disorder were grown outside the body, given a functional gene and returned to her blood; since those cells are not permanent the infusion had to be repeated, and a lasting cure needs the gene to be introduced at an early stage of life. Options B, C and D name digestive enzymes: amylase acts on starch, lipase on fats and trypsin on proteins, and a deficiency of any of them causes digestive trouble, not an immune disorder, so none of them is the subject of this first trial. Remember the disorder as severe combined immunodeficiency caused by the lack of this one enzyme.
Read the full article: Biotechnology and Its Applications: Notes and PYQs
Practice Questions
View allWhich enzyme cuts DNA at a specific recognition sequence and is therefore called molecular scissors?
- A.DNA ligase
- B.Restriction endonuclease
- C.DNA polymerase
- D.Reverse transcriptase
Show answer
A restriction endonuclease recognises a short palindromic sequence in DNA and cuts both strands there, leaving sticky ends that can pair with another piece cut by the same enzyme; Hind II was the first such enzyme to be discovered and EcoRI from Escherichia coli is the most widely used.
Read the full explanation →Which bacterium is used as a natural vector to transfer genes into plant cells?
- A.Escherichia coli
- B.Agrobacterium tumefaciens
- C.Bacillus thuringiensis
- D.Rhizobium leguminosarum
Show answer
This soil bacterium naturally transfers a part of its tumour inducing plasmid, called the Ti plasmid, into the cells of a dicotyledonous plant and causes crown gall disease; genetic engineers disarm the plasmid, insert the gene they want and use the bacterium as a vector, which is why it is…
Read the full explanation →The insect resistance gene of Bt cotton is obtained from which organism?
- A.A virus
- B.A soil bacterium
- C.A fungus
- D.An alga
Show answer
The genes called cry genes are taken from Bacillus thuringiensis, a bacterium of the soil that forms protein crystals during its spore stage.
Read the full explanation →Golden Rice is a genetically modified variety enriched with which substance?
- A.Iron
- B.Beta carotene
- C.Lysine
- D.Vitamin C
Show answer
Golden Rice carries genes that let the grain make beta carotene, the orange pigment that the human body converts into vitamin A, and the colour of the grain gives the variety its name; the aim is to reduce night blindness and childhood blindness in populations whose diet is mainly rice.
Read the full explanation →Which heat stable enzyme is used in the polymerase chain reaction?
- A.Taq polymerase
- B.DNA ligase
- C.EcoRI
- D.Lysozyme
Show answer
The polymerase chain reaction repeats three steps, denaturation at a high temperature, annealing of short primers and extension of the new strand, so the enzyme must survive near boiling water; Taq polymerase, obtained from the bacterium Thermus aquaticus of hot springs, does exactly that and lets a single DNA segment…
Read the full explanation →