Laboratory Techniques & Safety Flashcards
7 cards from real PCR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Laboratory Techniques & Safety flashcards as text
Which type of containment is most appropriate when extracting nucleic acid from potentially infectious clinical specimens?
Answer: A Class II biological safety cabinet
A Class II BSC protects the user, the sample, and the environment via HEPA-filtered airflow.
What is the best way to handle Taq polymerase stock when assembling reactions?
Answer: Keep it cold, mix gently by flicking or pipetting, spin briefly, and return it to the freezer promptly
Enzymes in glycerol should stay cold and be mixed gently to avoid denaturation and loss of activity.
Why are PCR master mixes typically prepared with roughly 10% excess volume?
Answer: To compensate for pipetting losses so every reaction receives a full volume
Extra volume covers dead volume and pipetting losses so the last reaction is not short.
Which pipetting technique is most accurate for viscous, glycerol-containing solutions like enzyme stocks?
Answer: Reverse pipetting
Reverse pipetting aspirates excess and leaves residual liquid in the tip, improving accuracy for viscous liquids.
Where should phenol-chloroform nucleic acid extraction be performed?
Answer: In a certified chemical fume hood with appropriate PPE
Phenol and chloroform are toxic and volatile, requiring a ducted chemical fume hood.
What PPE is essential when excising bands on a UV transilluminator?
Answer: A UV-blocking face shield covering eyes and skin
UV transilluminators can burn the skin and eyes, so full-face UV protection is required.
Why should lab coats be dedicated to specific areas (pre-PCR vs. post-PCR)?
Answer: To prevent amplicons on clothing from being carried into clean areas
Area-specific coats prevent transfer of amplified DNA on clothing into reagent and sample preparation spaces.
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