1.1 Lab techniques for biologists Flashcards
What presents a hazard in a lab?
Substances, organisms, and equipment in a laboratory can present a hazard.
Give four examples of hazards in a lab
Hazards in the lab include:
- Toxic or corrosive chemicals
- Heat or flammable substances
- Pathogenic organisms
- Mechanical equipment.
What is risk?
Risk is the likelihood of harm arising from exposure to a hazard.
What is risk assessment?
Risk assessment involves identifying control measures to minimise the risk.
Give three examples of control measures used to minimise risk
Control measures include:
- Using appropriate handling techniques
- Protective clothing and equipment
- Aseptic technique.
Linear dilutions
Dilutions in a linear dilution series differ by an equal interval, for example 0·1, 0·2, 0·3 and so on.
Log dilutions
Dilutions in a log dilution series differ by a constant proportion, for example 10-1, 10-2, 10-3 and so on.
How does a standard curve work?
Plotting measured values for known concentrations to produce a line or curve allows the concentration of an unknown to be determined from the standard curve.
How do pH buffers control pH?
Addition of acid or alkali has very small effects on the pH of a buffer, allowing the pH of a reaction mixture to be kept constant.
What are colorimeters used for?
Colorimeters can be used to quantify concentration and turbidity (cloudiness).
Before use, colorimeters must be…
Calibrated with an appropriate blank sample as a base line.
In a colorimeter, what is absorbance used to determine?
Absorbance can be used to determine concentration of a coloured solution using suitable wavelength filters.
In a colorimeter, what is percentage transmission used to determine?
Percentage transmission can be used to determine turbidity, such as cells in suspension.
What is a centrifuge used for?
A centrifuge is used to separate substances of differing density.
How does a centrifuge work?
Samples are spun so that more dense components settle in the pellet (solid) and less dense components remain in the supernatant (liquid).
What substances do paper and thin layer chromatography separate?
Paper and thin layer chromatography can be used for separating different substances such as amino acids and sugars.
How do paper and thin layer chromatography work?
The speed that each solute travels along the chromatogram depends on its differing solubility in the solvent used.
What is affinity chromatography used for?
Affinity chromatography is used to separate proteins.
How does affinity chromatography work?
A solid matrix or gel column is created with specific molecules (usually receptors) bound to it.
Soluble, target proteins in a mixture, with a high affinity for these molecules, become attached to them as the mixture passes down the column.
Other non-target molecules with a weaker affinity are washed out.
What is gel electrophoresis used for?
Gel electrophoresis is used to separate proteins and nucleic acids.
How does gel electrophoresis work?
Charged macromolecules move through an electric field applied to a gel matrix.
Native gels
Native gels do not denature the molecule so that separation is by shape, size and charge.
SDS–PAGE
SDS–PAGE gives all the molecules an equally negative charge and denatures them, separating proteins by size alone.
What is isoelectric point?
IEP is the pH at which a soluble protein has no net charge and will precipitate out of solution.