Laboratory Equipment & Techniques Flashcards
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Read the first 7 Laboratory Equipment & Techniques flashcards as text
In flow cytometry, the Forward Scatter (FSC) parameter primarily correlates with which cell property?
Answer: Cell size (volume)
Forward scatter (FSC) measures light diffracted around the cell and correlates with cell size, while side scatter (SSC) correlates with internal granularity.
Which technique is used to separate proteins based on their molecular weight by migration through a gel matrix under an electric field?
Answer: SDS-PAGE
SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis) denatures proteins with SDS (giving uniform negative charge) so they separate by size during electrophoresis.
A coulter counter (impedance cell counter) measures blood cell count by detecting:
Answer: Changes in electrical impedance as cells pass through an aperture
In impedance-based counters, cells suspended in electrolyte solution pass through a small aperture; each cell displaces electrolyte, causing a measurable change in electrical resistance.
When performing a Gram stain, which step differentiates gram-positive from gram-negative organisms?
Answer: Decolorization with alcohol/acetone
Decolorization with alcohol or acetone removes crystal violet-iodine complexes from gram-negative cells (thin peptidoglycan) but not from gram-positive cells (thick peptidoglycan).
Which of the following best describes the purpose of a 'delta check' in laboratory testing?
Answer: Comparing current patient result to a previous result from the same patient
A delta check flags when a patient's current result differs significantly from their previous result, helping detect specimen misidentification or acute patient changes.
In atomic absorption spectrophotometry (AAS), the light source used is a:
Answer: Hollow cathode lamp specific to the element being measured
Hollow cathode lamps emit a narrow spectral line specific to the element of interest, providing the precise wavelength needed for AAS measurements.
Which safety symbol on a chemical label indicates that the substance is flammable?
Answer: Flame symbol alone
The GHS flame pictogram (flame symbol without circle) indicates flammable liquids, gases, or solids; the flame over a circle indicates oxidizers.