🌸Chapter 9
Biotechnology: Principles and Processes
(2Marks)
Q1.
What is biotechnology?
Ans: Biotechnology is the branch of science that uses living organisms,
their cells, or enzymes to produce useful products for human welfare — such as
medicines, enzymes, and genetically modified crops.
Q2.
Define genetic engineering.
Ans: Genetic engineering is the manipulation of genetic material (DNA)
to change the genetic makeup of an organism — including isolation, cutting,
joining, and transferring of genes.
Q3.
What are the two core techniques that enabled modern biotechnology?
Ans:
1.
Genetic
Engineering
– for creating recombinant DNA.
2.
Maintenance
of sterile conditions and large-scale production – using bioreactors for growth and
product formation.
Q4.
What is recombinant DNA (rDNA)?
Ans: Recombinant DNA is a DNA molecule formed by joining DNA fragments
from different sources, usually using restriction enzymes and ligase.
Q5.
What are restriction enzymes?
Ans: Restriction enzymes (restriction endonucleases) are enzymes that
cut DNA at specific recognition sequences, called restriction sites.
Q6.
Who discovered restriction enzymes?
Ans: Werner Arber, Hamilton Smith, and Daniel Nathans — they were
awarded the Nobel Prize in 1978 for discovering restriction enzymes.
Q7.
What is the significance of EcoRI?
Ans: EcoRI is a restriction enzyme isolated from Escherichia coli
(strain RY13) which recognizes the sequence GAATTC and cuts between G
and A, producing sticky ends.
Q8.
What are sticky ends?
Ans: Sticky ends are short, single-stranded overhangs of DNA generated
after cleavage by certain restriction enzymes; they help in joining DNA
fragments easily.
Q9.
What are blunt ends?
Ans: Blunt ends are DNA fragments with no overhangs — both strands end
at the same base pair. They are formed when restriction enzymes cut straight
across the DNA.
Q10.
Define a cloning vector.
Ans: A cloning vector is a DNA molecule that carries foreign DNA into a
host cell and helps in its replication and expression (e.g., plasmids,
bacteriophages).
Q11.
Name two commonly used vectors in rDNA technology.
Ans:
1.
Plasmids
(e.g., pBR322, pUC18)
2.
Bacteriophages
(e.g., λ phage)
Q12.
What are plasmids?
Ans: Plasmids are small, circular, double-stranded DNA molecules found
in bacteria, independent of chromosomal DNA, often carrying antibiotic
resistance genes.
Q13.
Mention two essential features of a cloning vector.
Ans:
1.
Origin
of replication (Ori)
2.
Selectable
marker (e.g., antibiotic resistance gene)
Q14.
What is an origin of replication (Ori)?
Ans: Ori is a specific DNA sequence from where replication starts; it
allows the vector to replicate independently inside the host cell.
Q15.
What are selectable markers?
Ans: Selectable markers are genes in a vector that help identify
transformed cells from non-transformed ones, e.g., ampicillin resistance
(amp^r) and tetracycline resistance (tet^r).
Q16.
What is the function of a selectable marker?
Ans: It helps in the selection of recombinant host cells that have
successfully taken up the foreign DNA.
Q17.
What are cloning sites?
Ans: Cloning sites are specific recognition sequences on vectors where
restriction enzymes can cut and insert foreign DNA.
Q18.
What is a host cell?
Ans: A host cell is a living cell (e.g., E. coli) into which a
recombinant DNA molecule is introduced for replication and expression.
Q19.
Why is E. coli commonly used as a host in rDNA experiments?
Ans: E. coli grows rapidly, is easy to manipulate genetically,
and its entire genome and physiology are well known.
Q20.
What is transformation in bacteria?
Ans: Transformation is the process of introducing foreign DNA into a
bacterial cell.
Q21.
What is the role of CaCl₂ in bacterial transformation?
Ans: CaCl₂ increases the permeability of the bacterial cell wall,
allowing recombinant DNA to enter the cell.
Q22.
What is the full form of PCR?
Ans: Polymerase Chain Reaction.
Q23.
Who developed PCR and when?
Ans: Kary Mullis developed PCR in 1985.
Q24.
What is the function of PCR?
Ans: PCR amplifies (produces multiple copies of) a specific DNA segment
in vitro.
Q25.
Name the enzyme used in PCR and its source.
Ans: Taq polymerase, obtained from Thermus aquaticus — a
heat-tolerant bacterium.
Q26.
What are the three main steps of PCR?
Ans:
1.
Denaturation
(95°C)
2.
Annealing
(55°C)
3.
Extension
(72°C)
Q27.
What is gel electrophoresis used for?
Ans: It is used to separate DNA fragments based on size and charge
through an agarose gel matrix.
Q28.
Why does DNA move towards the anode during electrophoresis?
Ans: DNA is negatively charged (due to phosphate groups), so it migrates
towards the positively charged anode.
Q29.
Which dye is used to visualize DNA bands in gel electrophoresis?
Ans: Ethidium bromide — it binds to DNA and fluoresces orange under UV
light.
Q30.
What is a bioreactor?
Ans: A bioreactor is a large vessel used to grow cells or microorganisms
under controlled conditions for large-scale production of biological products.
Q31.
Name two types of bioreactors.
Ans:
1.
Stirred-tank
bioreactor
2.
Air-lift
bioreactor
Q32.
What is the function of the sparger in a bioreactor?
Ans: A sparger introduces sterile air bubbles into the culture to
provide oxygen for aerobic microbial growth.
Q33.
What is the function of the agitator in a bioreactor?
Ans: It mixes the culture uniformly and maintains even distribution of
nutrients and oxygen.
Q34.
What is downstream processing?
Ans: Downstream processing refers to the purification, quality testing,
and formulation of the final product after fermentation.
Q35.
Give one example of a product obtained through recombinant DNA technology.
Ans: Human insulin (Humulin) produced by E. coli.
Q36.
What are the main steps of recombinant DNA technology?
Ans:
1.
Isolation
of DNA
2.
Cutting
by restriction enzymes
3.
Ligation
into vector
4.
Insertion
into host
5.
Screening
and selection
6.
Large-scale
production
Q37.
Define palindromic sequence in DNA.
Ans: A palindromic sequence is a segment of DNA that reads the same on
both strands in the 5’→3’ direction (e.g., GAATTC).
Q38.
What is the importance of palindromic sequences in biotechnology?
Ans: They are recognized by restriction enzymes, which cut DNA at or
near these sequences.
Q39.
What is the role of DNA ligase?
Ans: DNA ligase joins two DNA fragments by forming phosphodiester bonds,
sealing the nicks between them.
Q40.
What is the role of host cell in genetic engineering?
Ans: The host cell allows replication, expression, and multiplication of
recombinant DNA to produce the desired protein.
Q41.
What is a selectable marker? Give examples.
Ans: A gene that helps identify transformed cells. Example: amp^r
(ampicillin resistance), tet^r (tetracycline resistance).
Q42.
What is an expression vector?
Ans: A vector designed to express the inserted gene in the host
organism, producing a specific protein.
Q43.
What is meant by amplification of DNA?
Ans: Amplification means producing multiple identical copies of a
specific DNA fragment, usually by PCR.
Q44.
Why are antibiotic resistance genes used in plasmid vectors?
Ans: They act as selectable markers to identify cells that have
successfully taken up the recombinant plasmid.
Q45.
What is meant by competent cell?
Ans: A bacterial cell that has been treated (e.g., with CaCl₂) to allow
uptake of foreign DNA is called a competent cell.
Q46.
What is the function of a cloning vector in gene cloning?
Ans: It carries the foreign gene into the host cell, allowing
replication and expression of that gene.
Q47.
Define ‘transformation’ and ‘transfection’.
Ans:
- Transformation: Uptake of naked DNA by
bacteria.
- Transfection: Introduction of DNA into
eukaryotic cells using a vector.
Q48.
What is the principle of gel electrophoresis?
Ans: DNA fragments are separated according to their size because smaller
fragments move faster through the agarose gel.
Q49.
What is the final step in genetic engineering?
Ans: Downstream processing — purification, testing, and formulation of
the desired gene product.
Q50.
What is the advantage of recombinant DNA technology over traditional breeding?
Ans: It allows precise insertion of desired genes across species
barriers and produces specific traits quickly and accurately.
