Laboratory Techniques & Safety Flashcards

Where should a technician look first for hazard, PPE, and spill information about a new PCR reagent?

Answer: The Safety Data Sheet (SDS) for that chemical

The SDS lists hazards, handling, PPE, first aid, and spill response for each chemical.

Why should PCR tubes be briefly centrifuged before opening after thawing or cycling?

Answer: To collect liquid at the bottom and reduce aerosol generation when the cap is opened

Spinning down removes droplets from the cap, lowering the risk of aerosols and contamination.

What is the function of the heated lid on a thermal cycler?

Answer: It prevents condensation and evaporation of the reaction onto the tube cap

Heating the lid above the block temperature keeps vapor from condensing on caps, maintaining reaction volume.

When should positive control template be added during reaction setup?

Answer: Last, after all samples and the NTC are capped

Adding the high-concentration positive control last minimizes the risk of contaminating samples and NTCs.

Which practice is correct when loading a microcentrifuge for a spin?

Answer: Place tubes of equal mass directly opposite each other to balance the rotor

An unbalanced rotor can damage the centrifuge and cause tube breakage or injury.

Why is unpolymerized acrylamide handled with gloves and care when casting gels for PCR product analysis?

Answer: It is a neurotoxin and suspected carcinogen

Acrylamide monomer is neurotoxic and absorbed through skin, whereas polymerized gel is far less hazardous.

For RT-PCR, which practice best protects RNA samples from degradation during handling?

Answer: Using RNase-free reagents and plasticware, changing gloves often, and treating surfaces with an RNase decontaminant

RNases are ubiquitous and stable, so RNase-free materials and surface decontamination are essential.