Glossary: Key Terms in BT-01

Term	Definition	NEET Context
Biotechnology	Application of biological systems and organisms to develop products and processes for specific use	Broad field; NEET focuses on rDNA technology
Recombinant DNA (rDNA)	DNA formed by joining sequences from two or more sources using restriction enzymes and ligase	Foundation of genetic engineering
Restriction endonuclease	Bacterial enzyme that cleaves DNA at specific palindromic sequences	"Molecular scissors"; EcoRI is the key example
Palindromic sequence	DNA sequence reading identically on both strands in 5'→3' direction	EcoRI site: 5'-GAATTC-3'
Sticky ends (cohesive ends)	Single-stranded DNA overhangs produced by staggered restriction cuts	Allow specific hybridization between compatible fragments
Blunt ends	Double-stranded ends with no overhangs, produced by straight cuts	Less efficient ligation; fewer cloning options
DNA ligase	Enzyme that forms phosphodiester bonds to join DNA fragments	"Molecular glue"; T4 DNA ligase in lab
Vector	DNA molecule that carries foreign DNA into a host cell	Plasmid (pBR322), phage (λ), Ti plasmid
Plasmid	Small circular, extrachromosomal DNA that replicates autonomously	pBR322 is the model cloning vector
Origin of replication (ori)	DNA sequence where replication begins	Required for autonomous plasmid replication
Selectable marker	Gene (usually antibiotic resistance) allowing selection of transformed cells	ampR and tetR in pBR322
Insertional inactivation	Disruption of a selectable marker gene by insert DNA	tetR disrupted in pBR322 recombinants
Ti plasmid	Tumor-inducing plasmid from A. tumefaciens; used for plant transformation	T-DNA integrates into plant genome; disarmed for use
T-DNA	Transfer DNA region of Ti plasmid that integrates into plant chromosome	Carries gene of interest after Ti plasmid disarming
Competent cell	Bacterial cell capable of taking up foreign DNA	Made competent by CaCl2 + heat shock
Transformation	Introduction of foreign DNA into a host cell	Key step in cloning; includes CaCl2, electroporation
PCR	Polymerase Chain Reaction; in vitro DNA amplification	Kary Mullis; 2^n amplification; Taq polymerase
Taq polymerase	Thermostable DNA polymerase from Thermus aquaticus	Survives PCR denaturation temperatures; used in PCR
Denaturation (PCR)	Separation of dsDNA into ssDNA at 94-98°C	Breaks hydrogen bonds between base pairs
Annealing (PCR)	Primer binding to complementary template at 50-65°C	Forward and reverse primers hybridize
Extension (PCR)	DNA synthesis by Taq at 72°C	Adds dNTPs in 5'→3' direction
dNTPs	Deoxyribonucleoside triphosphates; building blocks of DNA	Required for extension in PCR
Gel electrophoresis	Separation of DNA fragments by size through agarose gel using electric current	DNA migrates to anode; smaller = farther
Anode	Positive electrode toward which negatively charged DNA migrates	"A for Anode, A for Attracted (by DNA negative)"
Ethidium bromide	Fluorescent DNA intercalating dye; fluoresces orange under UV	Visualizes DNA bands in agarose gels
Bioreactor	Vessel for large-scale biological production under controlled conditions	Stirred-tank: agitator + sparger + pH/temp/O2 control
Sparger	Gas distribution device in bioreactor introducing sterile air	Provides O2 for aerobic fermentation
Downstream processing	Steps after bioreactor to obtain pure final product	Separation → Purification → Formulation → QC
Biolistics	Gene gun method; DNA-coated Au/W particles fired at cells	Best for plant cells and organelles; monocots
Electroporation	Brief electrical pulses create transient membrane pores for DNA entry	Versatile; high efficiency; works for many cell types
Microinjection	Direct injection of DNA into cell nucleus via glass micropipette	Precise; used for animal cells and oocytes
Crown gall	Plant tumor caused by A. tumefaciens Ti plasmid	Natural plant disease; Ti mechanism used in biotech