Error: Thinking DNA migrates toward the cathode in gel electrophoresis Correction: DNA has negatively charged phosphate groups → migrates toward the anode (positive pole). Cathode is negative; like charges repel.

Error: Confusing sticky ends and blunt ends — believing all restriction enzymes produce sticky ends Correction: EcoRI produces sticky ends (staggered cut); enzymes like SmaI produce blunt ends (straight cut). NEET specifically asks which type EcoRI produces.

Error: Stating that pBR322 has chloramphenicol resistance as a marker Correction: pBR322 markers are ampicillin (ampR) and tetracycline (tetR) resistance only. Chloramphenicol resistance is a feature of other vectors like pACYC.

Error: Believing that Taq polymerase adds a proofreading function Correction: Taq polymerase lacks 3'→5' exonuclease (proofreading) activity — it has a higher error rate than Pfu polymerase. Taq's key advantage is thermostability, not fidelity.

Error: Thinking the Ti plasmid is directly used as-is for plant transformation Correction: The Ti plasmid must be disarmed — tumor-inducing (oncogenic) genes on T-DNA are removed before use as a vector, otherwise it would cause crown gall tumors in the plant.

Error: Confusing PCR amplification formula — writing 2n instead of 2ⁿ Correction: After n cycles, copies = 2ⁿ (exponential). After 30 cycles ≈ 10^{9} copies.

Error: Assuming biolistics (gene gun) only works for bacteria Correction: Gene gun is specifically used for plants and other cells that are difficult to transform with conventional methods; bacteria are typically transformed with $CaCl_{2}$ + heat shock.

Error: Mixing up EcoRI source — stating it comes from E. coli strain K12 Correction: EcoRI is isolated from E. coli strain RY13, not K12.