Top 10 NEET Traps in BT-01

Trap 1: EcoRI makes blunt ends (NOT sticky ends)

• Error: Students confuse EcoRI (staggered cut → STICKY ends) with SmaI/EcoRV (straight cut → BLUNT ends)
• Correct: EcoRI always makes sticky ends with 5'-AATT overhang
• Memory hook: "EcoRI = Sticky ends; SmaI = Blunt ends"

Trap 2: DNA migrates toward cathode (NOT anode)

• Error: Confusing electron flow direction with molecular migration
• Correct: DNA (negative charge) → anode (positive electrode)
• Memory hook: "DNA is Negative → goes to the Anode (Positive)"

Trap 3: Taq polymerase has proofreading activity

• Error: Assuming Taq has 3'→5' exonuclease proofreading
• Correct: Taq lacks proofreading; Pfu polymerase (from Pyrococcus furiosus) has proofreading
• Consequence: Taq introduces errors (~10^-4 per base per cycle)

Trap 4: Lysozyme is used for plant cell wall lysis

• Error: Applying lysozyme to plant cells
• Correct: Lysozyme = bacterial walls (peptidoglycan); Cellulase = plant walls (cellulose)

Trap 5: Ti plasmid transforms both monocots and dicots equally

• Error: Assuming Ti plasmid works for all plants
• Correct: Ti plasmid is most effective for DICOTS; monocots require biolistics
• Why: Agrobacterium naturally infects dicots; monocot signaling is incompatible

Trap 6: The inserted gene goes into ampR (not tetR) in pBR322

• Error: Confusing which antibiotic gene is used for insertional inactivation
• Correct: Insert goes into tetR (BamHI, SalI sites). ampR remains intact for selection.
• Recombinant phenotype: grows on ampicillin (NOT on tetracycline)

Trap 7: Heat shock for transformation is at 37°C (normal E. coli growth temp)

• Error: Using 37°C (normal growth) instead of 42°C for heat shock
• Correct: CaCl2 treatment + heat shock at EXACTLY 42°C for 60-90 seconds

Trap 8: PCR amplification is linear (not exponential)

• Error: Thinking each cycle adds a fixed number of copies
• Correct: PCR is EXPONENTIAL: 2^n copies after n cycles (doubling each cycle)

Trap 9: For circular DNA, n cuts = n+1 fragments (linear rule)

• Error: Applying the linear DNA fragmentation rule to circular plasmids
• Correct: Circular DNA: n cuts = n fragments; Linear DNA: n cuts = n+1 fragments

Trap 10: Ethidium bromide stains protein (not DNA) for visualization

• Error: Confusing EtBr (DNA stain) with Coomassie blue (protein stain)
• Correct: Ethidium bromide intercalates DNA, fluoresces orange under UV; Coomassie blue stains protein in SDS-PAGE