(3)

(1)

Insulin consists of two short polypeptide chains—chain A and chain B—which are linked together by disulphide bonds. Insulin, in mammals, is synthesised as a prohormone which contains an extra stretch called the C-peptide. During maturation into insulin, this C-peptide is removed.

(4)

Serum and urine analysis are conventional methods of diagnosis, through which early detection is not possible.

(4)

In gene therapy for ADA deficiency, lymphocytes from patient’s blood are grown in culture outside the body. A functional ADA cDNA is then introduced into these lymphocytes, which are subsequently returned to patient. As these cells are not immortal, thus patient requires periodic infusion of genetically engineered lymphocytes.

(2)

(3)

Gene therapy is a collection of methods which allows genes to be inserted into a person’s cells and tissues to treat a disease.

(4)

PCR is used to detect mutations in gene in suspected cancer patients. A single stranded DNA or RNA tagged with a radioactive molecule (probe) is allowed to hybridise to its complementary DNA in a clone of cells followed by detection using autoradiography. The clone having the mutated gene will hence not appear on the photographic film, because the probe will not have complementarity with the mutated gene.

(4)

Enzyme Linked Immuno–Sorbent Assay (ELISA) is one of the techniques that serve the purpose of early diagnosis of disease.

(4)

The insulin produced by rDNA technology does not contain C peptide.

(2)

Adenosine deaminase deficiency (ADA) caused due to deletion of the gene for enzyme adenosine deaminase causes SCID which results in dysfunctioning of immune system.

(1)

(3)

Insulin consists of two short polypeptide chains: Chain A and Chain B, that are linked together by disulphide bridges.

(1)

Gene therapy is a technique of genetic engineering which involves replacement of a faulty/disease causing gene by a normal healthy functional gene. The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. This enzyme is very important for the immune system to function. The deficiency of this enzyme can lead to severe combined immune deficiency (SCID).

(2)

Human insulin is made up of 51 amino acids arranged in two polypeptide chains. Chain A has 21 amino acids and chain B has 30 amino acids. The two polypeptide chains are interconnected by disulphide bridges or S-S-linkages.

(1)

The recombinant DNA technological processes have made great impact in the area of health care by mass production of safe and more effective therapeutic drugs. In 1983, Eli Lily, an American company, first prepared two DNA sequences corresponding to A and B chains of human insulin and introduced them in plasmids of Escherichia coli to produce insulin chains. Chains A and B were produced separately, extracted and combined by creating disulphide bonds to form human insulin (humulin).

(1)

The correct answer is bacterium.

In 1983, Eli Lilly, an American company, prepared two DNA sequences corresponding to ‘A’ and ‘B’ chains of human insulin and introduced them in plasmids of E.coli (a gram negative bacterium) to produce insulin chains.