Distinguish between the 'principle' and the 'process' of genetic engineering as understood in your WBCHSE syllabus, using one example for each.

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The principle of genetic engineering is the set of biological facts that, together, explain why moving a gene from one organism into another can work at all: DNA is chemically identical across all life, the genetic code that translates DNA into protein is essentially universal so a foreign gene is read correctly by a host's machinery, and naturally occurring self-replicating molecules such as plasmids can be engineered into vectors that carry a foreign gene along with themselves every time the host divides. This is a scientific explanation, not a set of instructions. …

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CBSE 2025Set ANNUAL1 mark
$Q. Define genetic engineering.$
›Reveal solutionSolution

Genetic engineering is the deliberate, technique-based alteration of an organism's DNA to change or introduce specific traits, going beyond what conventional breeding can achieve.

Genetic engineering refers to techniques that allow scientists to alter the chemical structure of genetic material (DNA/RNA) directly — for example, by isolating a specific gene, cutting it with restriction enzymes, inserting it into a suitable vector, and introducing it into a host organism, where it can be expressed to confer a new, desired trait. Unlike conventional breeding, which relies on natural processes of sexual reproduction and selection, genetic engineering allows the direct transfer …

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$Q. Which one of the following products is present in huge amount in Transgenic Golden Rice?$
(a) Methionine
(b) Serine
(c) Lysine
(d) Carotene
›Reveal solutionSolution
Golden Rice is genetically engineered to accumulate beta-carotene, the precursor of Vitamin A, in its endosperm.

Golden Rice is a transgenic rice variety engineered by introducing genes for beta-carotene biosynthesis (originally from daffodil, Narcissus pseudonarcissus, and the bacterium Erwinia uredovora; later improved using a maize gene) into the rice genome.

The endosperm of Golden Rice accumulates a large amount of beta-carotene, giving the grain its golden-yellow colour. …
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CBSE 2023Set 57/1/11 markMCQ
$Q. Given below are two columns. In Column I is the list of four enzymes and in Column II is the list of functions of the given enzymes. Which one of the following options shows the enzymes matched with their respective functions correctly ? Column I (Enzyme) Column II (Function) P. DNA Ligase i. Removes nucleotides from ends of DNA Q. Restriction exonuclease ii. Extends primer on a DNA template R. Taq polymerase iii. Joins the DNA fragments S. Restriction endonuclease iv. Cuts DNA at a specific position Options :$
(a) P-i, Q-ii, R-iv, S-iii
(b) P-iv, Q-iii, R-ii, S-i
(c) P-i, Q-iv, R-iii, S-ii
(d) P-iii, Q-i, R-ii, S-iv
›Reveal solutionSolution
The correct matching pairs the enzymes with their specific functions: DNA Ligase joins DNA fragments, Restriction exonuclease removes nucleotides from DNA ends, Taq polymerase extends primers on a DNA template, and Restriction endonuclease cuts DNA at specific internal positions.

Enzymes are the workhorses of molecular biology, acting as catalysts for a vast array of biochemical reactions within living cells. In the realm of genetic engineering and biotechnology, specific enzymes are indispensable tools, allowing scientists to manipulate DNA with precision. Understanding the distinct roles of these molecular instruments is fundamental to comprehending processes like recombinant DNA technology and Polymerase Chain Reaction (PCR).

Let's delve into the functions of the enzymes listed:

DNA Ligase: This enzyme plays a crucial role in joining DNA fragments. When DNA is cut, either naturally during replication and repair or artificially during genetic engineering, there are breaks in the phosphodiester backbone. DNA ligase forms phosphodiester bonds between the 3'-hydroxyl end of one nucleotide and the 5'-phosphate end of another, effectively sealing these nicks. In recombinant DNA technology, it is used to join a desired DNA fragment (e.g., a gene of interest) into a vector plasmid.

Important

DNA ligase is often referred to as 'molecular glue' because it covalently links DNA fragments together.

Restriction Exonuclease: The term 'exonuclease' itself provides a strong clue to its function. 'Exo' means outside or end. An exonuclease is an enzyme that cleaves nucleotides one at a time from the end (either 3' or 5') of a polynucleotide chain. It progressively removes nucleotides from the terminal positions of a DNA molecule. This is distinct from endonucleases, which cut within the DNA strand.

Taq Polymerase: This is a DNA polymerase enzyme isolated from the thermophilic bacterium Thermus aquaticus. Its key characteristic is its heat stability, meaning it can withstand high temperatures without denaturing. This property makes it invaluable in the Polymerase Chain Reaction (PCR), where cycles of heating and cooling are required. Its primary function is to synthesize new DNA strands by extending primers on a DNA template, using deoxyribonucleotides as building blocks.

Note

The heat stability of Taq polymerase is critical for PCR, as it allows the enzyme to remain active even after the high-temperature denaturation step that separates DNA strands. …
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Q.Distinguish between the 'principle' and the 'process' of genetic engineering as understood in your WBCHSE syllabus, using one example for each.

Concept understanding — Genetic Engineering and Recombinant DNA Technology

Q.Distinguish between the 'principle' and the 'process' of genetic engineering as understood in your WBCHSE syllabus, using one example for each.

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