BIOTECHNOLOGY: PRINCIPLES AND PROCESSES · Comparison Tables

1. Traditional vs modern biotechnology

How biotechnology is used
Feature	Traditional biotechnology	Modern biotechnology
Basis	Uses organisms or enzymes in processes such as curd, bread and wine making.	Uses genetically modified organisms and molecular techniques, usually at larger scale.
Control over genes	No targeted alteration of DNA.	Desired DNA can be isolated, recombined and transferred.
Examples	Microbial fermentation.	Gene cloning, DNA vaccines, gene correction and recombinant protein production.
EFB definition	Integration of natural science and organisms, cells, parts thereof and molecular analogues for products and services.

2. Genetic engineering vs bioprocess engineering

Two core techniques of modern biotechnology
Feature	Genetic engineering	Bioprocess engineering
Main purpose	Alters DNA/RNA and introduces it into a host to change phenotype.	Maintains sterile conditions for large-scale growth of desired cells.
Key outcome	Recombinant DNA, gene cloning and gene transfer.	Large-scale production of antibiotics, vaccines, enzymes and other products.
Central requirement	Tools such as restriction enzymes, ligase, vector and host.	Controlled temperature, pH, nutrients, aeration and contamination-free ambience.

3. Exonuclease vs endonuclease

Nucleases that act on DNA
Feature	Exonuclease	Endonuclease
Site of action	Removes nucleotides from DNA ends.	Makes cuts at specific positions within DNA.
Use in recombinant DNA technology	Not the molecular scissors used for defined internal cuts.	Restriction endonucleases cut at specific recognition sequences.
Example of significance	Progressive removal from termini.	EcoRI recognises a palindromic sequence and can create sticky ends.

4. Sticky ends vs blunt ends

DNA ends after restriction digestion
Feature	Sticky ends	Blunt ends
Structure	Short single-stranded overhangs are left after staggered cutting.	Both DNA strands end at the same position; no overhang.
Pairing	Complementary overhangs hydrogen-bond readily.	No complementary overhang pairing.
NCERT relevance	Cutting source DNA and vector with the same enzyme yields matching ends for ligase.	Contrast helps explain why compatible sticky ends facilitate recombinant DNA formation.

5. Plasmid vs bacteriophage as cloning vector

Common bacterial cloning vehicles
Feature	Plasmid	Bacteriophage
Nature	Small circular, autonomously replicating DNA in bacterial cytoplasm.	Virus that infects bacteria.
Copy number	Variable; controlled in part by origin of replication.	Can have very high genome copy number per bacterial cell.
Use	Vector carries foreign DNA into host, e.g. pBR322.	Modified phages can carry larger DNA inserts.

6. Vector features: ori, marker and cloning site

What makes a vector useful
Feature	Function	NCERT point
Origin of replication (ori)	Site where replication begins; controls copy number of linked DNA.	High-copy ori helps recover many copies of target DNA.
Selectable marker	Identifies transformants and eliminates non-transformants.	Antibiotic-resistance genes such as ampicillin or tetracycline resistance in E. coli.
Cloning site	Restriction site at which foreign DNA is inserted.	Should preferably be single; multiple sites create unwanted fragments.
Insertional inactivation	Insertion disrupts a marker gene.	Disrupted beta-galactosidase gives colourless recombinant colonies on chromogenic substrate.

7. Transformant vs recombinant

Selection after DNA enters bacteria
Feature	Transformant	Recombinant
Meaning	Host cell that has taken up DNA during transformation.	Cell carrying a vector with the desired foreign DNA insert.
Selection	Selectable marker permits growth, e.g. on ampicillin.	Insertional inactivation or antibiotic-resistance pattern distinguishes it from non-recombinant transformants.
pBR322 example	May retain vector antibiotic resistance.	Insertion at BamHI site in tetracycline-resistance gene makes the recombinant tetracycline sensitive but ampicillin resistant.

8. DNA delivery methods

Introducing recombinant DNA into host cells
Method	Suitable host / procedure	Key point
Heat shock transformation	Bacteria treated with divalent cations, incubated with DNA on ice, briefly at 42 C, then returned to ice.	Competent cells take up recombinant DNA through pores.
Microinjection	Animal cells.	Recombinant DNA is injected directly into nucleus.
Biolistics / gene gun	Plant cells.	DNA-coated gold or tungsten micro-particles are bombarded at high velocity.
Disarmed pathogen vector	Plant or animal cells.	Modified pathogen transfers recombinant DNA without causing disease.

9. Gel electrophoresis vs PCR

Two essential DNA techniques
Feature	Gel electrophoresis	PCR
Purpose	Separates DNA fragments by size.	Amplifies a selected DNA segment in vitro.
Principle	Negatively charged DNA moves towards anode through agarose; smaller fragments move farther.	Repeated denaturation, primer annealing and extension make approximately billion copies.
Key materials	Agarose gel, electric field, ethidium bromide and UV for visualisation.	Template DNA, two primers, nucleotides and thermostable Taq polymerase from Thermus aquaticus.
Output	Separated bands; desired band can be cut out by elution.	Large quantity of gene of interest for cloning or analysis.

10. Stirred-tank bioreactor vs downstream processing

From cultured cells to marketed product
Feature	Bioreactor	Downstream processing
Stage	Large-scale biosynthesis.	After biosynthesis is complete.
Role	Provides optimum growth conditions and converts raw materials biologically into product.	Separates, purifies, formulates and quality-checks product before marketing.
Stirred-tank features	Agitator, oxygen delivery, foam, temperature and pH control, and sampling ports.	Strict quality control is required, especially for drugs.