Chapter 9: Biotechnology : Principles and Processes Short Questions | biology Class 12 CBSE

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Chapter 9: Biotechnology : Principles and Processes Short Questions | biology Class 12 CBSE | ByteNotes.in

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Question 1

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What is biotechnology according to the European Federation of Biotechnology (EFB)?

EFB defines biotechnology as the integration of natural science and organisms, cells, parts thereof, and molecular analogues for products and services.
This definition encompasses both traditional biotechnology (e.g., fermentation to make curd, wine, bread) and modern molecular biotechnology involving genetically modified organisms.
It is broader than the restricted modern definition, which refers only to processes using genetically modified organisms for large-scale production.

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Question 2

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Name the two core techniques that enabled the birth of modern biotechnology and state what each involves.

The first core technique is genetic engineering, which involves altering the chemistry of genetic material (DNA and RNA) and introducing it into host organisms to change their phenotype.
The second core technique is bioprocess engineering, which involves maintaining a sterile, contamination-free environment in chemical engineering processes to grow desired microbes or eukaryotic cells in large quantities.
Together, these techniques allow both the manipulation of genetic material and the large-scale manufacture of biotechnological products such as antibiotics, vaccines, and enzymes.

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Question 3

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What is the origin of replication (ori) in a cloning vector and why is it important?

The origin of replication (ori) is a specific DNA sequence in the vector from which DNA replication initiates within the host cell.
Any piece of alien DNA linked to this sequence can be made to replicate inside the host, allowing multiplication of the foreign gene.
The ori also controls the copy number of the linked DNA, so choosing a vector with a high-copy-number ori increases the yield of the target gene.

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Question 4

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How are restriction endonucleases named? Give one example.

The first letter in the name comes from the genus and the next two letters from the species of the prokaryotic cell from which the enzyme was isolated.
The letter following the three-letter abbreviation indicates the strain, and Roman numerals denote the order in which the enzyme was isolated from that strain.
Example: EcoRI is isolated from Escherichia coli strain RY 13; 'E' = Escherichia, 'co' = coli, 'R' = strain RY 13, 'I' = first enzyme isolated from that strain.

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Question 5

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What is a palindromic nucleotide sequence? Give an example from the chapter.

A palindromic sequence in DNA is a sequence of base pairs that reads the same on both strands of the DNA when read in the same orientation (5' to 3').
Unlike word palindromes, the palindrome is read on two complementary strands rather than a single sequence reversed.
Example from the chapter: 5'-GAATTC-3' on one strand and 3'-CTTAAG-5' on the other strand; reading both in 5' to 3' direction gives the same sequence, which is the recognition site for EcoRI.

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Question 6

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What are sticky ends? How are they formed and why are they important?

Sticky ends are short, single-stranded overhanging nucleotide sequences produced when a restriction enzyme cuts DNA slightly away from the centre of the palindromic recognition site, leaving unpaired bases.
They are formed because the enzyme cuts each strand at different positions within the palindrome, generating staggered cuts rather than blunt ends.
Sticky ends are important because they can form hydrogen bonds with complementary sticky ends from other DNA fragments, facilitating precise ligation by DNA ligase to form recombinant DNA.

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Question 7

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Differentiate between exonucleases and endonucleases.

Exonucleases remove nucleotides from the ends of a DNA molecule, degrading DNA from its termini inward.
Endonucleases make cuts at specific internal positions within a DNA molecule, cleaving phosphodiester bonds in the interior of the strand.
Restriction endonucleases are a specific class of endonucleases that cut at specific recognition sequences (palindromes) and are used as molecular tools in genetic engineering.

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Question 8

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What is gel electrophoresis? Why does DNA move toward the anode during the process?

Gel electrophoresis is a technique used to separate DNA fragments by their size by forcing them through an agarose gel matrix under an electric field.
DNA is a negatively charged molecule due to its phosphate backbone, so it migrates toward the positively charged anode when an electric field is applied.
Smaller DNA fragments move faster and farther through the agarose gel matrix, while larger fragments move more slowly, resulting in size-based separation of fragments.

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Question 9

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What is a selectable marker and why is it required in a cloning vector?

A selectable marker is a gene incorporated into a cloning vector that enables identification and elimination of non-transformants (cells that did not take up the recombinant DNA).
It selectively permits the growth of only transformed cells; for example, an antibiotic resistance gene ensures that only cells containing the vector survive on antibiotic-containing media.
Examples of selectable markers for E. coli include genes conferring resistance to ampicillin, chloramphenicol, tetracycline, or kanamycin.

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Question 10

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Explain insertional inactivation as a method to identify recombinant colonies.

In insertional inactivation, foreign DNA is inserted within the coding sequence of the β-galactosidase gene present in the vector, disrupting the gene's function.
When a chromogenic substrate is added to the growth medium, non-recombinant bacteria (where β-galactosidase gene is intact) produce a blue colour; recombinant bacteria (where the gene is inactivated by insert) appear white.
This colour-based selection allows easy visual identification of recombinant colonies without the need for two-plate plating, unlike the cumbersome dual-antibiotic selection method.

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Question 11

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What is a recombinant protein? Give the context in which this term is used.

A recombinant protein is a protein encoded by a gene cloned from one organism (the gene of interest) and expressed in a heterologous (different) host organism.
This occurs when a foreign gene is introduced into a host cell and expressed under appropriate conditions, producing a protein that is not naturally made by that host.
Large-scale production of recombinant proteins is achieved using bioreactors, and the protein is subsequently isolated and purified through downstream processing.

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Question 12

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What is 'elution' in the context of gel electrophoresis?

Elution refers to the step in which a specific separated DNA band is cut out from the agarose gel after electrophoresis.
The DNA fragment of interest is then extracted from the excised gel piece using appropriate buffers or centrifugation methods.
The purified DNA fragment obtained by elution is then used in constructing recombinant DNA by joining it with a cloning vector.

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Question 13

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Why must bacterial cells be made 'competent' before transformation? How is competency achieved?

DNA is a hydrophilic molecule and cannot pass through the lipid bilayer of cell membranes on its own; therefore, bacterial cells must be specially treated to increase their permeability to DNA.
Competency is achieved by treating bacterial cells with a specific concentration of a divalent cation, such as calcium ions (Ca2+), which increases the efficiency of DNA entry through pores in the cell wall.
The competent cells are then incubated with recombinant DNA on ice, subjected to a brief heat shock at 42°C, and returned to ice, enabling the bacteria to take up the recombinant DNA.

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Chapter sections

Chapter 9: Biotechnology : Principles and Processes | Short Questions

What is biotechnology according to the European Federation of Biotechnology (EFB)?

Name the two core techniques that enabled the birth of modern biotechnology and state what each involves.

What is the origin of replication (ori) in a cloning vector and why is it important?

How are restriction endonucleases named? Give one example.

What is a palindromic nucleotide sequence? Give an example from the chapter.

What are sticky ends? How are they formed and why are they important?

Differentiate between exonucleases and endonucleases.

What is gel electrophoresis? Why does DNA move toward the anode during the process?

What is a selectable marker and why is it required in a cloning vector?

Explain insertional inactivation as a method to identify recombinant colonies.

What is a recombinant protein? Give the context in which this term is used.

What is 'elution' in the context of gel electrophoresis?

Why must bacterial cells be made 'competent' before transformation? How is competency achieved?

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