Laboratory Techniques

Question 1

What are hazards in a lab?

Answer 1

Toxic or corrosive chemicals, heat or flammable substances, pathogenic organisms and mechanical equipment

Question 2

What is risk?

Answer 2

Risk is the likelihood of harmonising from exposure to a hazard.

Question 3

What is risk assessment?

Answer 3

Risk assessment involves identifying control measures to minimise risk

Question 4

Control measures

Answer 4

Using appropriate handling techniques, protective clothing and equipment and aseptic technique

Question 5

How do dilutions in a linear dilution series differ?

Answer 5

By an equal interval,for example 0.1,0.2,0.3 etc

Question 6

How do dilutions in a log series differ?

Answer 6

By a constant proportion

Question 7

How do you produce a standard curve?

Answer 7

Plot measured values for known concentrations to produce a line or curve that allows the concentration of an unknown to be determined

Question 8

How does a buffer control pH?

Answer 8

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

Question 9

What does a colorimeter do?

Answer 9

Quantify concentration and turbidity

Question 10

How does a colorimeter work?

Answer 10

It is calibrated with on appropriate blank as a baseline,a suitable wavelength-filter is used to determine absorbanceand then work out concentration of a coloured solution. Percentage transmission is used to determine turbidity

Question 11

How does centrifuge separate substances?

Answer 11

By density. More dense components settle in the pellet.less dense components remain in the supernatant.

Question 12

What does paper and thin layer chromatography separate?

Answer 12

Separating different substances such as amino acids and sugars.The speed that each solute travels along the chromatogram depends on its differing solubility in the solvent used.

Question 13

Principle of gel electrophoresis

Answer 13

Separates proteins and nucleic acids. Charged macromolecules more through an electric field applied to a gel matrix.

Question 14

Native gels

Answer 14

Separate their proteins by their size, shape and charge. Native gels don’t denature the molecule

Question 15

Sds-page

Answer 15

Separates proteins by size alone. Gives all the molecules an equally negative charge and denatures them

Question 16

What is an isoelectric point?

Answer 16

The pH at which a soluble protein has no het charge and will precipitate out of solution.

Question 17

How can you use IEPs to separate proteins.

Answer 17

If the solution is buffered to a specific pH, only the proteinsthat have that IEP will precipitate.

Question 18

How can you use IEPs in electrophoresis?

Answer 18

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

Question 19

What are immunoassay techniques used for?

Answer 19

To detect and identity specific proteins using stocks of antibodies with the same specificity.

Question 20

What are monoclonal antibodies?

Answer 20

Stocks of antibodies with the same specificity.

Question 21

How do antibodies detect proteins?

Answer 21

An antibody specific to the protein antigen is linked to a chemical label

Question 22

What kinds of labels are there?

Answer 22

The label is often a reporter enzyme that produces a colour change, but chemiluminesence, fluorescence and other reporters can be used.in some cases the assay uses a specific antigen to detect the presence of antibodies.

Question 23

What is Western blotting?

Answer 23

A technique used after sds-page, the separated proteinsfrom the gel are transferred to a solid medium, the proteins can be identified using specific antibodies that have reporter enzymes attached.

Question 24

What is bright- field microscopy commonly used to observe.

Answer 24

Whole organisms, parts of organisms, thin sections of dissected tissue ar individual cells.

Question 25

How does fluorescence microscopy work?

Answer 25

Specific fluorescent labels bird to ad visualise certain molecules or structures within cells or tissues.

Question 26

What does aseptic technique do?

Answer 26

Eliminates unwanted microbial contaminants when culturing micro-organisms or cells.

Question 27

What does aseptic technique involve?

Answer 27

The sterilisation of equipment and culture media by heat ar chemical means and subsequent exclusion of microbial contaminate.

Question 28

How can a microbial culture be started?

Answer 28

Using an inoculum of microbial cells on an agar medium, or in a broth with suitable nutrients. Many culture media exist that promote the growth of specific types of cells and microbes.

Question 29

How de animal cells grown?

Answer 29

In medium containing growth factors from serum.

Question 30

What are growth factors?

Answer 30

Proteins that promote cell growth and proliferation.they ae essential for the culture of most animal cells.

Question 31

What is the difference between a primary and turn cell line in culture?

Answer 31

Primary cell lines can divide a limited number of times, whereas tumour cell lines con perform unlimited divisions.

Question 32

How is the number of colony-forming units in a liquid microbial culture counted?

Answer 32

It is plated and often serially diluted to achieve a suitable colony count. Haemocytometers are used to count all colonies, vital staining is required to identity and count viable cells.