1.1 Lab Techniques for Biologists Flashcards
What is a risk?
A risk is defined as the likelihood of harm arising from exposure to a hazard.
What is a hazard?
A hazard is anything that can cause harm or injury to people, or that can cause ecological damage if it is released from the laboratory.
How are hazards and risks controlled in a lab?
A risk assessment.
What does precise mean?
The closeness of repeated measurements to one another.
What does accurate mean?
The closeness of a measured value to the true (expected) value.
What does reliable mean?
Consistent values in repeats and independent replicates.
What does valid mean?
Variables are controlled so that any measured effect is likely to be due to the independent variable.
What is a buffer?
A buffer is a solution that keeps the pH of a solution constant. If acids or alkalis are added, they have very small effects.
Why are buffers important in experiments?
Buffers are important as pH can affect proteins (enzymes) so changes in pH could affect the rate of reactions.
Buffers can set the pH of a solution to ensure it stays within the pH range for a reaction or maintains the optimum pH for the reaction.
What is a linear dilution?
Different volumes of a stock solution create different dilutions of the solution.
eg.
1ml stock + 9ml solvent = 10% solution
What is a serial (log) dilution?
Dilutions differ by a constant proportion.
eg. by a tenth each time…
1… 0.1… 0.01… 0.001..
What are colourimetres used for?
Colourimetres can be used to quantify the concentration and turbidity of a solution.
Colourimetres must be calibrated with a blank sample to provide a baseline reading of absorbance or transmission.
Absorbance can be used to determine the concentration of a coloured solution using suitable wavelength filters.
Percentage transmission can be used to determine turbidity eg cells in suspension.
What is a standard curve?
Plotting known measurements on a graph allows you to determine unknown values.
What is centrifugation?
Centrifugation is a method for separating materials in suspension according to their differing density.
A centrifuge spins materials at high speeds and separates substances in liquids according to their density. More dense components are pushed to the bottom to form the pellet. Less dense components remain in the liquid - the supernatant.
What is paper and thin-layer chromatography?
In paper and thin-layer chromatography, amino acids or sugars can be separated according to their characteristics of solubility.
The speed at which each solute travels along the chromatogram depends on the solubility in the solvent used. More soluble solutes move faster and further along a chromatogram. Less soluble moves slower and less along a chromatogram.
Thin-layer chromatography is similar to paper chromatography but solutes move through a thin layer of absorbent material coating a slide instead of paper.
