Lab Techniques

Question 1

What can present a hazard?

Answer 1

Substances, organisms, and equipment in a laboratory can present a hazard.

Question 2

What is an example of a hazard in a lab?

Answer 2

Hazards in the lab include toxic or corrosive chemicals, heat or flammable substances, pathogenic organisms, and mechanical equipment.

Question 3

What is a risk?

Answer 3

A risk is the likelihood of harm arising from exposure to a hazard.

Question 4

What does risk assessment involve?

Answer 4

Risk assessment involves identifying control measures to minimise the risk.

Question 5

What do control measures include?

Answer 5

Control measures include using appropriate handling techniques, protective clothing and equipment, and aseptic technique.

Question 6

How do dilutions in a linear dilution series differ?

Answer 6

Dilutions in a linear dilution series differ by an equal interval, for example 0.1, 0.2, 0.3 and so on.

Question 7

How do dilutions in a log dilution differ?

Answer 7

Dilutions in a log dilution series differ by a constant proportion, for example 10^-1, 10^-2, 10^-3 and so on.

Question 8

How do you determine an unknown from a standard curve?

Answer 8

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.

Question 9

Use of buffers to control pH

Answer 9

Addition of acid or alkali has very small effects on the pH of a buffer, allowing the oH of a reaction mixture to be kept constant.

Question 10

Method and uses of a colorimeter to quantify concentration and turbidity.

Answer 10

Calibration with appropriate blank as a baseline; use of absorbance ti determine concentration of a coloured solution using suitable wavelength filters; use of percentage transmission to detract turbidity, such as cells in suspension.

Question 11

Use of centrifuge to separate substances of differing density.

Answer 11

More dense components settle in the pellet; less dense components remain in the supernatant.

Question 12

What is paper and thin layer chromatography used for?

Answer 12

Paper and thin chromatography can be used for separating different substances such as amino acids and sugars.

Question 13

What does the speed that each solute travels along the chromatogram depend on?

Answer 13

Its differing solubility in the solvent used.

Question 14

Principle of affinity chromosome and its use in separating proteins.

Answer 14

A solid matrix or gel column is created with specific molecules bound to the matrix or gel. Soluble, target proteins inna 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.

Question 15

Principle of gel electrophoresis and its use in separating proteins and nucleic acids.

Answer 15

Charged macromolecules move through an electrical field applied to a gel matrix.

Question 16

Native gels

Answer 16

Native gels do not denature the molecule so that separation is done by shape, size, and charge.

Question 17

SDS-PAGE

Answer 17

SDS-PAGE gives all molecules an equally negative charge and denatures them, separating proteins by size alone.

Question 18

What does IEP stand for

Answer 18

Isoelectric points

Question 19

What is IEP?

Answer 19

IEP is the pH at which a soluble protein has no net charge and will precipitate out of the solution.
If a solution is buffered to a special pH, only the protein(s) that have an IEP of the pH will precipitate.

Question 20

How can proteins be separated using their IEPs in electrophoresis?

Answer 20

Soluble proteins can be separated using an electric field and a pH gradient. A protein stops migrating through the gel at its IEP in the pH gradient because it has no net charge.

Question 21

What are immunoassay techniques used for?

Answer 21

They are used to detect and identify specific proteins.

Question 22

What do immunoassay techniques use?

Answer 22

Stocks of antibodies with the same specificity, known as monoclonal antibodies.

Question 23

An antibody specific to the protein antigen is linked to a chemical ‘label’. What often is this ‘label’ ?

Answer 23

The ‘label’ is often a reporter enzyme producing a colour change, but chemiluminescence, fluorescence and other reporters can be used.

Question 24

What is used after SDS-PAGE electrophoresis?

Answer 24

Western blotting

Question 25

What is bright-field microscopy is commonly used for?

Answer 25

Observing whole organisms, parts of organisms, thin sections of dissected tissue or individual cells.

Question 26

What does fluorescence microscopy use and what does it visualise?

Answer 26

Fluorescence microscopy uses specific fluorescent labels to bind to and visualise certain molecules or structures within cells or tissues.

Question 27

Aseptic technique eliminates what?

Answer 27

Unwanted microbial contaminants when culturing micro-organisms or cells.

Question 28

What does aseptic technique involve?

Answer 28

Aseptic technique involves the sterilisation of equipment and culture media by heat or chemical means and subsequent exclusion of microbial contaminants.

Question 29

How can a microbial culture be started?

Answer 29

Using an inoculum of microbial cells on an agar medium, or in a broth with suitable nutrients.

Question 30

Many culture media exist that promote what?

Answer 30

The growth of specific types of cells and microbes.

Question 31

What are animal cells grown in?

Answer 31

Animal cells are grown in medium containing growth factors from serum.

Question 32

What are growth factors?

Answer 32

Proteins that promote cell growth and proliferation. Growth factors are essential for the culture of most animal cells.

Question 33

What is the difference between primary cell lines and tumour cell lines?

Answer 33

In culture, primary cell lines can divide a limited number of times, whereas tumour cell lines can perform unlimited divisons

Question 34

Plating out of a liquid microbial culture on solid media allows what?

Answer 34

The number of colony forming units to be counted and the density of cells in the culture estimated.

Question 35

What is often needed to achieve a suitable colony count?

Answer 35

Serial dilution

Question 36

What is required to identify and count viable cells in the use of a haemoctyometer.

Answer 36

Vital staining