Transgenic mice are being used to test the safety of the polio vaccine. In 1997, the first transgenic cow, Rosie, produced human protein-enriched milk (2.4 grams per litre). The milk contained the human alpha-lactalbumin and was nutritionally a more balanced product for human babies than natural cow-milk. Answer : (c)

SCID is the most severe form of primary immunodeficiencies. The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. The disorder is caused due to the deletion of the gene for adenosine deaminase. In some children ADA deficiency can be cured by bone marrow transplantation; in others it can be treated by enzyme replacement therapy, in which functional ADA is given to the patient by injection. Answer : (a)

Restriction nucleases is also known as molecular scissors as they cut any DNA fragment at specific position. Restriction endonucleases make cuts at specific positions within the DNA. Answer : (d)

Golden rice is an improved variety of transgenic basmati rice, which gives high yield and rich in vitamin A. Answer : (a)

Bacillus thuringiensis (Bt) is a species of bacteria that lives in soil. It makes proteins that are toxic to some insects when eaten, but not others. The proteins are not toxic to humans because, like all mammals, we cannot activate them. Bt is not toxic to non-target wildlife. Answer : (b)

Human insulin is the synthetic insulin which is grown in the laboratories. Human insulin is laboratory created by growing insulin proteins within E.coli bacteria (Escherichia coli). Answer : (a)

Plasmid DNA act as vectors to transfer the piece of DNA attached to it. plasmids and bacteriophages have the ability to replicate within bacterial cells independent of the control of chromosomal DNA. Answer : (b)

The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. The disorder is caused due to the deletion of the gene for adenosine deaminase. Answer : (d)

Genetic engineering (also called genetic modification) is a process that uses laboratory-based technologies to alter the DNA makeup of an organism. This may involve changing a single base pair (A-T or C-G), deleting a region of DNA or adding a new segment of DNA. Answer : (a)

When cut by the same restriction enzyme, the resultant DNA fragments have the same kind of ‘sticky-ends’ and, these can be joined together (end-to-end) using DNA ligases. Answer : (d)

A probe is a fragment of DNA or RNA of variable length which is used in DNA or RNA samples to detect the presence of nucleotide sequences that are complementary to the sequence in the probe. Answer : (a)

DNA ligase is a specific type of enzyme, a ligase, that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. Answer : (a)

restriction enzyme, also called restriction endonuclease, a protein produced by bacteria that cleaves DNA at specific sites along the molecule. In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms. Answer : (c)

Complementary DNA (cDNA) is a DNA copy of a messenger RNA (mRNA) molecule produced by reverse transcriptase. Answer : (d)

Answer : (b)

The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel. Hence, the smaller the fragment size, the farther it moves. Answer : (b)

The Bt brinjal has been developed to give resistance against lepidopteron insects, in particular the Brinjal Fruit and Shoot Borer (Leucinodes orbonalis)(FSB) by forming pores in the digestive system. Answer : (d)

The enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. If the process of replication of DNA is repeated many times, the segment of DNA can be amplified to approximately billion times, i.e., 1 billion copies are made. Such repeated amplification is achieved by the use of a thermostable DNA polymerase (isolated from a bacterium, Thermus aquaticus), which remain active during the high temperature induced denaturation of double stranded DNA. Answer : (b)

The cutting of DNA by restriction endonucleases results in the fragments of DNA. These fragments can be separated by a technique known as gel electrophoresis. Since DNA fragments are negatively charged molecules they can be separated by forcing them to move towards the anode under an electric field through a medium/matrix. Nowadays the most commonly used matrix is agarose which is a natural polymer extracted from sea weeds. Answer : (b)

A reporter gene is a gene cloned with a DNA sequence of interest inserted into an expression vector followed by transfer to target tissues. They are used as indicators to study gene expression in target tissue for pharmaceutical and molecular biology research. Answer : (a)

Xenograft: The transplant of an organ, tissue, or cells to an individual of another species. Answer : (b)

Retroviruses have also been disarmed and are now used to deliver desirable genes into animal cells. So, once a gene or a DNA fragment has been ligated into a suitable vector it is transferred into a bacterial, plant or animal host (where it multiplies). Answer : (c)

The first restriction endonuclease–Hind II, whose functioning depended on a specific DNA nucleotide sequence was isolated and characterised five years later. It was found that Hind II always cut DNA molecules at a particular point by recognising a specific sequence of six base pairs. This specific base sequence is known as the recognition sequence for Hind II. Besides Hind II, today we know more than 900 restriction enzymes that have been isolated from over 230 strains of bacteria each of which recognise different recognition sequences Answer : (b)

Each restriction endonuclease functions by ‘inspecting’ the length of a DNA sequence. Once it finds its specific recognition sequence, it will bind to the DNA and cut each of the two strands of the double helix at specific points in their sugar -phosphate backbones. Each restriction endonuclease recognises a specific palindromic nucleotide sequences in the DNA. Answer : (a)

Enzyme DNA polymerase extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. If the process of replication of DNA is repeated many times, the segment of DNA can be amplified to approximately billion times, i.e., 1 billion copies are made. Such repeated amplification is achieved by the use of a thermostable DNA polymerase (isolated from a bacterium, Thermus aquaticus), which remain active during the high temperature induced denaturation of double stranded DNA. Answer : (c)

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 to produce insulin chains Answer : (d)

cry Bt- toxin protein exists as inactive protein but once an insect ingests the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut, which solubulise the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis and eventually cause death of the insect. Specific Bt toxin genes were isolated from B. thuringiensis and incolyorated into the several plants such as cotton. The toxin is coded by a gene named cry. There are a number of them, eg, the proteins encoded by the genes cry IAc and cry II Ab control the cotton bollworms, that of cry IAb control corn borers. Answer : (c)

restriction enzyme, also called restriction endonuclease, a protein produced by bacteria that cleaves DNA at specific sites along the molecule. In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms. Answer : (b)

RNA interfernce (RNAi) is a novel strategy to prevent infestation of nematode. RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate Answer : (a)

E. coli cloning vector pBR322 shows restriction sites such as Hind III, EcoR I, BamH I, Sal I, Pvu II, Pst I, Cla I. Other options except (b) are name of restriction site whereas option (b) is vector/plasmid. Answer : (b)

complementary DNA is DNA synthesized from a single-stranded RNA template in a reaction catalyzed by the enzyme reverse transcriptase. cDNA is often used to clone eukaryotic genes in prokaryotes. Answer : (d)

Repeated amplification in PCR technology is achieved by the use of a thermostable DNA polymerase, isolated from a bacterium Thermus aquaticus. It remain active during the high temperature induced denaturation of double stranded DNA. Answer : (a)

'Centromere' is found in chromosomes where two chromatids are attached.Option (a) is wrong All genes are present in all cells. Option (b) is Correct nucleosome isa structural unit of a eukaryotic chromosome, Option(c) is wrong In eukaryotic organisms, the DNA is packaged with histone proteins to create a compacted structure called a nucleosome. A nucleosome consists of a molecule of DNA wrapped around a core of eight histone proteins (an octamer).Option (d) is wrong Answer : (b)

Glutathione S-transferase (GST) enzymes play role in Herbicide Metabolism Answer : (d)

Restriction enzymes belong to a larger class of enzymes called nucleases. These are of two kinds; exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA. Answer : (d)

Gene therapy: Here genes are inserted into a person’s cells and tissues to treat a disease. Correction of a genetic defect involves delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene. Answer : (d)

Milstein and Köhler described the first technique developed for stable monoclonal antibody production in 1975. This technique consists of creating a hybridoma, a stable hybrid cell capable of producing a single type of antibody against a specific epitope present in an antigen. Answer : (b)

Genetic engineering : Techniques to alter the chemistry of genetic material (DNA and RNA), to introduce these into host organisms and thus change the phenotype of the host organism. Answer : (d)

During splicing, introns (Non-coding regions) are removed and exons (Coding Regions) are joined together Answer : (d)

EcoRI comes from Escherichia coli RY 13. In EcoRI, the letter ‘R’ is derived from the name of strain. Roman numbers following the names indicate the order in which the enzymes were isolated from that strain of bacteria. Answer : (d)

Restriction Endonuclease:These are enzymes that cut DNA at specific sites. They are properly called restriction endonucleases because they cut the bonds in the middle of the polynucleotide chain. DNA Ligase:This enzyme repairs broken DNA by joining two nucleotides in a DNA strand. It is commonly used in genetic engineering to do the reverse of a restriction enzyme, i.e. to join together complementary restriction fragments. Answer : (c)

When cut by the same restriction enzyme, the resultant DNA fragments have the same kind of ‘sticky-ends’ and, these can be joined together (end-to-end) using DNA ligases. Option (d) is incorrect. DNA polymerase is isolated from a bacterium, Thermus aquaticus, which remain active during the high temperature induced denaturation of double stranded DNA. Option(c) is incorrect. pBR322 is a plasmid and was one of the first widely used E. coli cloning vectors. Optin (b) is incorrect. The soil-dwelling bacterium Agrobacterium tumefaciens causes crown gall disease of dicots, which is a type of plant tumor. It does so by inserting a piece of a large plasmid it carries into susceptible plant cells. The plasmid is known as the Ti plasmid and the inserted DNA is called T-DNA Option (a) is correct. Answer : (a)

"Humulin" or Recombinant Human Insulin. The correct sequence is 1.Synthesis of the gene for human insulin artificially. 2.Insertion of human insulin in plasmid. 3.Introduction of recombinant plasmid into E.coli. 4. Culturing recombinant E.coli in bioreactors. 5.Extraction of a recombinant gene product from E coli. 6.Purification of Humulin. Answer : (b)

Flavr Savr, a genetically modified tomato, was the first commercially grown genetically engineered food to be granted a license for human consumption. Answer : (c)

Two of the most important bacteria used in genetic engineering experiments are Escherichia coli (E. coli) and Agrobacterium tumefaciens. E. coli in genetic engineering include the production of human insulin. The tumor inducing (Ti) plasmid of Agrobacterium tumifaciens has now been modified into a cloning vector which is no more pathogenic to the plants but is still able to use the mechanisms to deliver genes of our interest into a variety of plants Answer : (b)

PCR is based on three simple steps required for any DNA synthesis reaction: (1) denaturation of the template into single strands; [temperature: 94°C-95°C] (2) annealing of primers to each original strand for new strand synthesis;[Temperature:50°C-56°C] (3) extension of the new DNA strands from the primers. [temperature: 72°C] Answer : (d)

Nick named 'protato' the protein packed genetically modified (GM) potato contains 60 per cent more protein than a wild-type potato and has increased levels of several amino acids. In transgenic potato, the enhanced protein (albumin) localizes inside cytoplasm/vacuole. Answer : (d)

Hybridoma is a culture of hybrid cells that results from the fusion of B cells and myeloma cells. Hybridoma technology is a method for producing large numbers of identical antibodies (also called monoclonal antibodies) Answer : (b)

EcoRI cuts the DNA between bases G and A only when the sequence GAATTC is present in the DNA. Answer : (d)

Answer : (b)