Misconceptions: 15+ Common Student Errors in BT-01

#	Misconception	Correction
1	EcoRI produces blunt ends	EcoRI produces STICKY ends (staggered cut; 5'-AATT overhang). SmaI/EcoRV produce blunt ends.
2	DNA migrates toward the cathode (−)	DNA migrates toward the ANODE (+) because DNA has a net NEGATIVE charge from phosphate groups.
3	Taq polymerase has proofreading activity	Taq LACKS 3'→5' proofreading exonuclease. Pfu polymerase has proofreading.
4	Taq polymerase is from E. coli	Taq is from THERMUS AQUATICUS (thermophilic hot spring bacterium), not E. coli.
5	Heat shock for transformation is at 37°C	Heat shock is at 42°C, not 37°C (37°C is E. coli normal growth temperature).
6	For circular DNA, n cuts = n+1 fragments	For CIRCULAR DNA: n cuts = n fragments. The n+1 rule applies to LINEAR DNA only.
7	The Ti plasmid transforms both monocots and dicots equally	Ti plasmid works efficiently for DICOTS only. Monocots require BIOLISTICS.
8	pBR322 has one selectable marker	pBR322 has TWO selectable markers: ampR (ampicillin) AND tetR (tetracycline).
9	Blue-white screening uses pBR322	Blue-white screening (lacZ gene) uses pUC vectors, NOT pBR322. pBR322 uses insertional inactivation.
10	PCR amplification is linear	PCR amplification is EXPONENTIAL: 2^n copies, not n × 2 copies.
11	DNA ligase cuts DNA	DNA ligase JOINS (seals) DNA. Restriction endonucleases CUT DNA.
12	Lysozyme is used to break plant cell walls	Lysozyme breaks BACTERIAL walls (peptidoglycan). CELLULASE breaks plant walls (cellulose).
13	Competent cells are made by heat shock alone	Competent cells require CaCl2 FIRST, then heat shock. Both steps are necessary.
14	Ethidium bromide is a protein stain	Ethidium bromide stains DNA (intercalates between bases). Coomassie/Silver stain proteins.
15	The sparger in a bioreactor mixes the culture	The AGITATOR mixes the culture. The SPARGER introduces sterile air (O2 supply).
16	pBR322 insert goes into ampR for insertional inactivation	Standard insertional inactivation puts the insert into tetR $\frac{via BamHI}{SalI sites}$ , NOT ampR.
17	Microinjection is used for plant cells	Microinjection is used for ANIMAL cells and oocytes. BIOLISTICS (gene gun) is for plants.
18	PCR requires a living cell to work	PCR is an IN VITRO technique — performed entirely in a test tube with purified components.