biology - unit 1.1 Flashcards
What can present a hazard?
Substances, organisms, and equipment in a laboratory.
What do hazards in the lab include?
Toxic or corrosive chemicals, heat or flammable substances, pathogenic organisms, and mechanical equipment.
What is risk?
The likelihood of harm arising from exposure to a hazard.
What does risk assessment involve?
Identifying control measures to minimise the risk.
What do control measures include?
Using appropriate handling techniques, protective clothing and equipment, and aseptic technique.
What do dilutions in a linear dilution series differ by?
An equal interval, for example 0·1, 0·2, 0·3 and so on.
What do dilutions in a log dilution series differ by?
A constant proportion, for example 10-1, 10-2, 10-3 and so on.
What allows the concentration of an unknown to be determined from the standard curve?
Plotting measured values for known concentrations to produce a line or curve.
What do buffers allow?
The pH of a reaction mixture to be kept constant, as the addition of acid or alkali has very small effect on the pH of a buffer.
On a colorimeter, what is the use of absorbance?
Used to determine concentration of a coloured solution using suitable wavelength filters.
On a colorimeter, what is the use of percentage transmission?
Used to determine turbidity, such as cells in suspension.
What is used as a baseline in calibration?
Appropriate blank.
What is a centrifuge used for?
To separate substances of differing density. More dense components settle in the pellet; less dense components remain in the supernatant.
What can paper and thin layer chromatography be used for?
Separating different substances such as amino acids and sugars.
What does the speed that each solute travels along the chromatogram depend on?
Its differing solubility in the solvent used.
What is created for affinity chromatography?
A solid matrix or gel column with specific molecules bound to the matrix or gel.
What becomes attached to these specific molecules bound to the matrix or gel?
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 does gel electrophoresis do?
It helps separate proteins and nucleic acids.
What do charged macromolecules move through?
An electric field applied to a gel matrix.
What do native gels do?
They separate proteins by their shape, size and charge.
What do native gels do so that separation is by shape, size and charge?
They do not denature the molecule.
What does SDS-PAGE do?
It separates proteins by size alone.
What does SDS-PAGE give?
All the molecules an equally negative charge and denatures them, separating proteins by size alone.
How can proteins be separated from a mixture?
Using their isoelectric points (IEPs).
What is IEP?
The pH at which a soluble protein has no net charge and will precipitate out of solution.
If the solution is buffered to a specific pH, what will precipitate?
Only the protein(s) that have an IEP of that pH will precipitate.
How can proteins also be separated?
Using their IEPs in electrophoresis.
How can soluble proteins be separated?
Using an electric field and a pH gradient.
When does a protein stop migrating through the gel?
At its IEP in the pH gradient because it has no net charge.
What are immunoassay techniques used for?
To detect and identify specific proteins.
What do these immunoassay techniques use?
Stocks of antibodies with the same specificity, known as monoclonal antibodies.
What is an antibody specific to the protein antigen linked to?
A chemical ‘label’.
What is the ‘label’ often?
A reporter enzyme producing a colour change, but chemiluminescence, fluorescence and other reporters can be used.
In some cases, what does the assay use?
A specific antigen to detect the presence of antibodies.
What is western blotting?
A technique, used after SDS–PAGE electrophoresis.
What happens to the separated proteins from the gel?
They are transferred (blotted) onto a solid medium.
How can the proteins be identified?
Using specific antibodies that have reporter enzymes attached.
What is bright-field microscopy commonly used for?
To observe whole organisms, parts of organisms, thin sections of dissected tissue or individual cells.
What does fluorescence microscopy use?
Specific fluorescent labels to bind to and visualise certain molecules or structures within cells or tissues.
What does aseptic technique eliminate?
Unwanted microbial contaminants when culturing micro-organisms or cells.
What does aseptic technique involve?
The sterilisation of equipment and culture media by heat or chemical means and subsequent exclusion of microbial contaminants.
How can a microbial culture be started?
Using an inoculum of microbial cells on an agar medium, or in a broth with suitable nutrients.
What do many culture media which exist do?
They promote the growth of specific types of cells and microbes.
Where are animal cells grown?
In medium containing growth factors from serum.
What are growth factors?
Proteins that promote cell growth and proliferation.
What are growth factors essential for?
The culture of most animal cells.
In culture, what can primary cell lines do?
They can divide a limited number of times, whereas tumour cells lines can perform unlimited divisions.
What does plating out of a liquid microbial culture on solid media allow?
The number of colony-forming units to be counted and the density of cells in the culture estimated.
What is serial dilution often needed for?
To achieve a suitable colony count.
What is a haemocytometer used for?
To estimate cell numbers in a liquid culture.
What is vital staining required for?
To identify and count viable cells.
METHOD FOR HAEMOCYTOMETER
GEL ELECTROPHORESIS
AFFINITY CHROMOTOGRAPHY
USE OF CENTRIFUGE
METHOD FOR COLORIMETER
PRODUCTION OF STANDARD CURVE
METHOD OF LOG DILUTIONS
METHOD OF LINEAR DILUTIONS
