Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant. Answer:(a)

Answer:(a)

Taq polymerase helps in amplification of DNA fragments in PCR technique. Enzyme taq polymerase extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. (i) is correct. Transformation is a procedure through which a piece of DNA is introduced in a host bacterium. (iv) is correct. The cells can also be multiplied in a continuous culture system. This type of culturing method produces a larger biomass leading to higher yields of desired protein. (v) is correct. Antibiotic resistance genes are selectable markers. Desirable genes are the ones which are introduced in the vector for getting desired protein product. (ii) is incorrect. The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel. (iii) is incorrect. The processes of separation and purification are collectively referred to as downstream processing. (vi) is incorrect. Answer:(a)

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. Answer:(c)

Restriction endonucleases are used in genetic engineering to form ‘recombinant’ molecules of DNA, which are composed of DNA from different sources/genomes. Restriction enzymes cut the strand of DNA between the same two bases on the opposite strands. This leaves single stranded portions at the ends. There are overhanging stretches called sticky ends on each strand. These are named so because they form hydrogen bonds with their complementary cut counterparts. This stickiness of the ends facilitates the action of the enzyme DNA ligase. Answer:(d)

selectable markers have been developed which differentiate recombinants from non-recombinants on the basis of their ability to produce colour in the presence of a chromogenic substrate. Answer:(a)

Restriction endonuclease cut the strand of DNA a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands. This leaves single stranded portions at the ends. There are overhanging stretches called sticky ends on each strand. These are named so because they form hydrogen bonds with their complementary cut counterparts. Answer:(a)

A retrovirus is a virus that uses RNA as its genomic material. Upon infection with a retrovirus, a cell converts the retroviral RNA into DNA, which in turn is inserted into the DNA of the host cell. Answer:(b)

DNA gyrase, or simply gyrase, is an enzyme within the class of topoisomerase Gyrase belongs to a class of enzymes known as topoisomerases that are involved in the control of topological transitions of DNA. topological properties of the genetic material, including DNA underwinding and overwinding, knotting, and tangling, profoundly influence virtually every major nucleic acid process Answer:(a)

The origin of replication (also called the replication origin) is a particular sequence in a genome at which replication is initiated Answer:(a)

Cosmid vectors are designed to clone large fragments of DNA and to grow their DNA as a virus or as a plasmid. Answer:(a)

Hybridoma is a culture of hybrid cells that results from the fusion of B cells and myeloma cells. Fused cells are incubated in HAT medium (hypoxanthine-aminopterin-thymidine medium) for roughly 10 to 14 days. Aminopterin blocks the pathway that allows for nucleotide synthesis. Hence, unfused myeloma cells die. In this way, only the B cell-myeloma hybrids survive, since the HGPRT gene coming from the B cells is functional. These cells produce antibodies (a property of B cells) and are immortal (a property of myeloma cells). Answer:(a)

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. Answer:(c)

Restriction endonucleases make cuts at specific positions within the 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. Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin. Answer:(a)

Antibiotics can be produced biotechnologically by identifying and culturing the antibiotic-producing microorganism. The antibiotic gene is isolated and then linked with plasmid vector. The ability to multiply copies of antibiotic resistance gene in E. coli was called cloning of antibiotic resistance gene in E. coli. Answer:(d)

The second phase of evolution and development of biotechnology can be called 'Classical Biotechnology'. This phase existed from 1800 to almost the middle of the twentieth century. Early examples of biotechnology include breeding animals and crops, and using microorganisms to make cheese, yoghurt, bread, beer and wine. Answer:(c)

Gene amplification refers to a number of natural and artificial processes by which the number of copies of a gene is increased. Answer:(c)

The technique involved Southern blot hybridisation using radiolabelled VNTR as a probe. It included: (i) isolation of DNA (ii) digestion of DNA by restriction endonucleases, (iii) separation of DNA fragments by electrophoresis, (iv) transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon (v) hybridisation using labelled VNTR probe, and (vi) detection of hybridised DNA fragments by autoradiography. A schematic representation of DNA fingerprinting. Answer:(a)

The z gene codes for beta-galactosidase (β-gal), which is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units, galactose and glucose. Multiple cloning sites are a feature that allows for the insertion of foreign DNA without disrupting the rest of the plasmid which makes it extremely useful in biotechnology, bioengineering, and molecular genetics. Answer:(a)

genome size is clearly not an indicator of the genomic or biological complexity of an organism. A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. The largest known gene is the human dystrophin gene, which has 79 exons spanning at least 2,300 kilobases. the structural gene in a transcription unit could be said as monocistronic (mostly in eukaryotes) or polycistronic (mostly in bacteria or prokaryotes). In eukaryotes, the monocistronic structural genes have interrupted coding sequences – the genes in eukaryotes are split. The coding sequences or expressed sequences are defined as exons Answer:(a)

pBR322 is a plasmid and was one of the first widely used E. coli cloning vectors. Created in 1977 in the laboratory of Herbert Boyer at the University of California, San Francisco. Answer:(b)

The initial phase is the lag phase where bacteria are metabolically active but not dividing. The exponential or log phase is a time of exponential growth. Answer:(c)

Answer:(d)

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. 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 from wells Answer:(a)

The European Federation of Biotechnology (EFB) was established by European scientists in 1978. Answer:(b)

Chromosome 1 has most genes (2968), and the Y has the fewest (231). Answer:(b)

The cutting of DNA at specific locations became possible with the discovery of the so-called ‘molecular scissors’– restriction endonuclease. Answer:(d)

Restriction endonuclease and DNA ligase are essential for recombination. Answer:(b)

Restriction endonucleases are used in genetic engineering to form ‘recombinant’ molecules of DNA, which are composed of DNA from different sources/genomes. Answer:(b)

When you insert a piece of alien DNA into a cloning vector and transfer it into a bacterial, plant or animal cell, the alien DNA gets multiplied. In almost all recombinant technologies, the ultimate aim is to produce a desirable protein. Hence, there is a need for the recombinant DNA to be expressed. If any protein encoding gene is expressed in a heterologous host, it is called a recombinant protein. Answer:(c)

Cosmid vectors are hybrids between plasmid and phage λ vectors. The classic example of cosmid vector is c2RB, which carries an origin of replication and a cloning site and has antibiotic-resistant genes. As with the phage λ vector, the cosmid vector encodes the cos sequences required for packaging of DNA into λ capsid. Cosmids can contain 37 to 52 (normally 45) kb of DNA. Cos sequences are ~200 base pairs long and essential for packaging. They contain a cosN site where DNA is nicked at each strand, 12 bp apart, by terminase. This causes linearization of the circular cosmid with two "cohesive" or "sticky ends" of 12bp Answer:(a)

A shuttle vector is a vector (usually a plasmid) constructed so that it can propagate in two different host species. Shuttle vectors include plasmids that can propagate in eukaryotes and prokaryotes. Answer:(d)

Hybridoma is a culture of hybrid cells that results from the fusion of B cells and myeloma cells. Assertion is true but reason is false. Answer:(c)

Fermentation is a chemical process by which carbohydrates, such as starch and glucose, are broken down anaerobically. Fermentation has many health benefits and is used in the production of alcoholic beverages, bread, cheese. Answer:(c)

Gel electrophoresis is a technique to separate fragments of DNA. 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. Now-a-days the most commonly used matrix is agarose which is a natural polymer extracted from seaweeds (e.g., Gelidium, Gracilaria, Gigartina, etc.). Answer:(c)

Steps involved are as followed: 1. Synthesis of the gene for human insulin artificially. 2. Insertion of human insulin into 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:(c)

Ti plasmid is a genetically engineered plasmid which has the ability of inducing cell division or tumour formation in plants. The Ti plasmid is formed by modifying the plasmid of Agrobacterium tumefaciens through genetic engineering. The limitation of this Ti-plasmid mediated gene transfer is that it can't be used to transform monocots such as grasses, corn. Answer:(d)

Restriction endonucleases are used in genetic engineering to form ‘recombinant’ molecules of DNA, which are composed of DNA from different sources/genomes. Answer:(b)

Chimera, in genetics, an organism or tissue that contains at least two different sets of DNA, most often originating from the fusion of as many different zygotes (fertilized eggs). As per options, it can be a plasmid containing foreign DNA of two species. Answer:(b)

Yeast artificial chromosome (YAC) is one engineered vector used to clone DNA sequences in yeast cells. Segments of an organism's DNA, up to one million base pairs in length, can be inserted into YACs. Yeast artificial chromosomes (YACs) are shuttle-vectors that can be amplified in bacteria and employed for the cloning and manipulation of large deoxyribonucleic acid (DNA) inserts (up to 3 Mb pairs) in the yeast Saccharomyces cerevisiae. Answer:(a)

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 Answer:(a)

DNA fingerprinting is a very quick way to compare the DNA sequences of any two individuals. DNA fingerprinting is the basis of paternity testing, in case of disputes. In addition to application in forensic science, it has much wider application, such as in determining population and genetic diversities. Answer:(d)

Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure because it requires simultaneous plating on two plates having different antibiotics. Therefore, alternative selectable markers have been developed which differentiate recombinants from non-recombinants on the basis of their ability to produce colour in the presence of a chromogenic substrate. In this, a recombinant DNA is inserted within the coding sequence of an enzyme, β-galactosidase. This results into inactivation of the gene for synthesis of this enzyme, which is referred to as insertional inactivation. The presence of a chromogenic substrate gives blue coloured colonies if the plasmid in the bacteria does not have an insert. Presence of insert results into insertional inactivation of the β-galactosidase gene and the colonies do not produce any colour, these are identified as recombinant colonies. Answer:(b)

Because the plasmid only has a site for enzyme Y to cut, it will need to be cut with enzyme Y in order to create an opening to insert the gene. cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid Answer:(c)

Pfu polymerase and Tli polymerase have been isolated are also thermostable. Answer:(c)

A bacterium uses a restriction enzyme to defend against bacterial viruses called bacteriophages, or phages. When a phage infects a bacterium, it inserts its DNA into the bacterial cell so that it might be replicated. The restriction enzyme prevents replication of the phage DNA by cutting it into many pieces. Answer:(d)

The genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc., are considered useful selectable markers for E. coli. The normal E. coli cells do not carry resistance against any of these antibiotics. Answer:(a)

Transcription makes mRNA from DNA but polymerase chain reaction make multiple copies of a segment of DNA Answer:(d)

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. Restriction endonucleases are used in genetic engineering to form ‘recombinant’ molecules of DNA, which are composed of DNA from different sources/genomes. 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. Answer:(d)