This set of Class 12 Biology Chapter 12 Multiple Choice Questions & Answers (MCQs) focuses on “Biotechnological Applications in Medicine: Gene Therapy”.
1. A person with the hereditary disease can be cured with the help of _________
a) gene therapy
Explanation: Gene therapy is a technique used to cure many hereditary diseases. It involves changing the genome in order to prevent or cure diseases. It is one of the most successful techniques used to cure hereditary diseases or to cure deficiency of various hormones.
2. A collection of methods that allows correction of a gene that has been diagnosed in child/embryo is called _________
b) gene therapy
Explanation: A collection of methods that allows the correction of a gene that has been diagnosed in a child/embryo is called gene therapy. It consists of various processes. In this, the defective genes are corrected and replaced with normal, healthy genes.
3. In gene therapy, the gene defects are cured in a child or ________ stage.
Explanation: In gene therapy, the gene defects are cured in child or embryonic stage. This phase is chosen to avoid complications and each and every cell will receive a healthy, functional gene.
4. In gene therapy, the genetic defect is corrected by delivery of _______ gene into the individual.
Explanation: In gene therapy, the genetic defect is corrected by the delivery of a normal gene into the individual. This normal gene when replaced cures that deficiency. It is a functional gene and is useful in the curing of that disorder.
5. The inserted normal gene takes over the function of _________ gene.
Explanation: In gene therapy, the inserted normal gene takes over the function of the non-functional gene. This non-functional gene is also called as an incorrect or mutant gene. This change in function is useful in successfully curing of the disease.
6. In which year was the first clinical gene therapy given?
Explanation: Gene therapy is a technique that involves the introduction of a normal gene to compensate for the abnormal gene in a diseased organism. The first therapeutic use of gene therapy was done in September 1990 by French Anderson.
7. In 1990 the first gene therapy was given to treat which deficiency?
b) Vitamin E
d) Adenosine deaminase
Explanation: The first gene therapy was given to a 4-year-old child to treat Adenosine deaminase (ADA) deficiency. ADA deficiency is an autosomal recessive metabolic and immune disorder.
8. ADA stands for _______
a) Adenine nucleotide amine
b) Vitamin A deficiency
c) Adenosine deaminase
d) A double bond amine
Explanation: ADA stands for Adenosine deaminase. It is an enzyme that brings about the breakdown of purines. In humans, it helps in the development and maintenance of the immune system. Thus ADA deficiency leads to immune disorder.
9. ADA deficiency is caused due to ________ of the gene for adenosine deaminase.
Explanation: ADA deficiency is caused due to the deletion of the gene responsible for synthesizing the enzyme adenosine deaminase. This enzyme is involved in purine metabolism and its deficiency leads to immune disorder.
10. ______ is an alternative method to cure ADA deficiency.
a) Bone marrow transplantation
Explanation: Bone marrow transplantation is an alternative method to cure ADA deficiency. Another method is enzyme replacement therapy. But a drawback of both these therapies is they are not completely curative.
11. In the first step of gene therapy, ________ from the blood of the patient are grown in a culture outside of the body.
a) red blood cells
Explanation: In the first step of gene therapy, lymphocytes from the blood of the patient are grown in a culture outside of the body. Lymphocytes are the white blood cells responsible for maintaining the immunity of an individual. The defective gene is identified and replaced with the normal functional gene.
12. A functional ADA cDNA is introduced into the patient’s lymphocytes using _______ vector.
Explanation: In gene therapy, a functional ADA cDNA is introduced into the patient’s lymphocytes using a retroviral vector. Retroviruses are used because they have an enzyme reverse transcriptase. This enzyme converts single-stranded RNA into double-stranded DNA and this DNA then further integrates within the genome without disturbing its stability.
13. Lymphocytes are immortal.
Explanation: Lymphocytes are mortal cells. They are the white blood cells responsible for maintaining the immunity of an individual. Most lymphocytes are short-lived ranging from weeks to months, while few cells such as B and T lymphocytes can live for years.
14. Introduction of gene isolate from bone marrow producing ADA should be introduced at what age to permanently cure ADA?
c) Old age
d) Embryonic stage
Explanation: To treat any gene-related disorder with the help of gene therapy, the normal gene should be introduced within the cells in embryonic stages. This is done in the early stages because modification in germ cells causes modification in all cells of that organism. Thus all cells will receive the normal genes.
15. What is introduced into lymphocytes to cure ADA?
c) ADA cDNA
Explanation: To cure ADA through gene therapy, ADA cDNA was introduced into lymphocytes. cDNA is made from a single-stranded RNA template with the help of enzyme reverse transcriptase. This helps in the introduction of the new genes within an organism without causing toxicity in cells.
16. What kind of disease can be cured with the help of gene therapy?
Explanation: Gene therapy is a technique used to cure hereditary diseases. It involves the introduction of a normal gene into the early embryonic stages to compensate for abnormal or missing genes. The normal gene is introduced into the organism using retrovirus or plasmid.
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