Question

When gene targetting involving gene amplification is attempted in an individual’s tissue to treat disease, it is known as [NEET 2021]

(a) biopiracy

(b) gene therapy

(c)molecular diagnosis

(d) safety testing

Answer/Explanation

Ans. (b)

Gene therapy is a type of treatment designed to modify the expression of an individual’s genes or to correct abnormal genes to treat a disease. Gene amplification is common in cancer cells, and some amplified genes may cause cancer cells to grow or become resistant to anticancer drugs. The presence of gene amplification can have a prognostic and a diagnostic value and can help in orienting therapy in specific tumour types.

Question

 With regard to insulin choose the correct options.
I. C-peptide is not present in mature insulin.
II. The insulin produced by rDNA technology has C-peptide.
III. The pro-insulin has C-peptide.
IV. A-peptide and B-peptide of insulin are interconnected by disulphide bridges.

Choose the correct answer from the options given below. [NEET 2021]

(a) II and IV

(b) II and III

(c) I, III and IV

(d) I and IV

Answer/Explanation

Ans. (c)

Statement I, III and IV are correct. Insulin consists of two short polypeptide chains $A$ and $B$ which are linked together by disulphide bridges. In mammals insulin is synthesised as pro hormone which contain an extra stretch called the C, peptide also called pro-insulin. $C$-peptide is removed during maturation into insulin and is not present in mature insulin.
Statement II is incorrect and be corrected as It is challenging to produce insulin by using rDNA techniques because it is difficult to assemble insulin into its mature form using rDNA technique. Thus, $\mathrm{C}$ – peptide is absent in insulin produced by rDNA technology.

Question

 Which of the following statements is not correct? [NEET (Sep.) 2020]

(a) The proinsulin has an extra peptide called C-peptide

(b) The functional insulin has $A$ and $B$ chains linked together by hydrogen bonds

(c) Genetically engineered insulin is produced in E-coli

(d) In man, insulin is synthesised as a proinsulin

Answer/Explanation

Ans. (b)

Statement in option (b) is incorrect because Insulin is composed of two peptide chains referred to as the $A$ chain and $B$ chain. $A$ and $B$ chains are linked together by two disulphide bonds, and an additional disulphide is formed within the A chain. Insulin molecules have a tendency to form dimers in solution due to hydrogen-bonding between the C-termini of B chains.

Question

 In India, the organisation responsible for assessing the safety of introducing genetically modified organisms for public use is [NEET 2018]

(a) Research Committee on Genetic Manipulation(RCGM)

(b) Council for Scientific and Industrial Research (CSIR)

(c) Indian Council of Medical Research (ICMR)

(d) Genetic Engineering Appraisal Committee (GEAC)

Answer/Explanation

Ans. (d)

In India, Genetic Engineering Approval Committee, i.e., GEAC (NCERT) is responsible for assessing the safety of introducing genetically modified organisms for public use. GEAC comes under the Ministry of Environment and Forests (MOE \& F) while the Review Committee on Genetic Manipulation (RCGM) comes under Department of Biotechnology.
The Council of Scientific and Industrial Research (CSIR) is the largest research and development organisation in India. The Indian Council of Medical Research (ICMR) is the apex body in India for the formulation, coordination and promotion of biomedical research.
Note The name of GEAC is changed to Genetic Engineering Appraisal Committee from Genetic Engineering Approval Committee in 2010.

Question

 The two polypeptides of human insulin are linked together by [NEET 2016, Phase I]

(a) phosphodiester bonds

(b) covalent bonds

(c) disulphide bridges

(d) hydrogen bonds

Answer/Explanation

Ans. (c)

In humans, insulin is produced by $\beta$-cells of pancreas. It is synthesised as prohormone in which two polypeptides are synthesised with an extra stretch of ‘C’ polypeptide. During maturation extra stretch of ‘C’ polypeptide is separated and two polypeptide chains ( $A$ and $B$ ) are linked together by disulphide linkages (bridges).

Question

Which kind of therapy was given in 1990 to a four-year-old girl with Adenosine Deaminase (ADA) deficiency? [NEET 2016, Phase II]

(a) Gene therapy

(b) Chemotherapy

(c) Immunotherapy

(d) Radiation therapy

Answer/Explanation

Ans. (a)

The first clinical gene therapy was given in 1990 to a 4 years old girl with Adenosine Deaminase (ADA) deficiency. ADA deficiency is a disorder caused due to the deletion of the gene for adenosine deaminase. Gene threapy is the technique of genetic engineering that allows correction of a gene defect that has been diagnosed in child/embryo. In this therapy a normal healthy functional gene is inserted and the faulty gene is replaced.

Question

 The first human hormone produced by recombinant DNA technology is [CBSE AIPMT 2014]

(a) insulin

(b) estrogen

(c) thyroxin

(d) progesterone

Answer/Explanation

Ans. (a)

The first human hormone produced by recombinant DNA technology is insulin. It is peptide hormone, which controls the level of blood sugar. It is formed by joining of two polypeptide chain by disulphide bonds.

Question

Human insulin is being commercially produced from a transgenic species of [CBSE AIPMT 2008]

(a) Rhizobium

(b) Saccharomyces

(c) Escherichia

(d) Mycobacterium

Answer/Explanation

Ans. (c)

In 1983 an American company Eli Lily produced the first genetically engineered insulin by first synthesising two DNA sequences corresponding to $\alpha$ and $\beta$ insulin chains. The two DNA sequences or genes were made to fuse with plasmids of Escherichia coli and later allowed to form insulin chains.

Question

 Production of a human protein in bacteria by genetic engineering is possible because [CBSE AIPMT 2005]

(a) bacterial cell can carry out the RNA splicing reactions

(b) the human chromosome can replicate in bacterial cell

(c) the mechanism of gene regulation is identical in humans and bacteria

(d) the genetic code is universal

Answer/Explanation

Ans. (d)

Production of human protein in bacteria by genetic engineering is possible because the genetic code is universal as a codon codes for the same amino acid in all the organisms.

Question

 The genetic defect-Adenosine Deaminase (ADA) deficinecy may be cured permanently by [CBSE AIPMT 2009]

(a) periodic infusion of genetically engineered lymphocytes having functional ADA cDNA

(b) administering adenosine deaminase activators

(c) introducing bone marrow cells producing ADA into cells at early embryonic stages

(d) enzyme replacement therapy

Answer/Explanation

Ans. (a)

Severe Combined Immuno Deficiency (SCID) caused by Adenosine Deaminase Deficiency (ADA) is the first genetic disorder to be treated with gene therapy. T-cell directed gene transfer was useful in the treatment of $\mathrm{ADA}-\mathrm{SCID}$, whereas the retroviral- mediated gene transfer to haematopoietic stem cells was insufficient for achievement of clinical benefits.

Question

 ELISA is used to detect viruses where the key reagent is [CBSE AIPMT 2004, 03]

(a) alkaline phosphatase

(b) catalase

(c) DNA probe

(d) RNase

Answer/Explanation

Ans. (a)
Alkaline phosphate is the key reagent used during detection of virus in ELISA test. The test work by detecting antibodies/substances or protein which are produced in blood when virus is present. The reagents are used to provide antibody-antigen complex in a specialised ELISA plate.

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