U1: KA1 - Lab techniques for biologists

Question 1

What is a hazard?

Answer 1

Anything which could cause harm.

Question 2

What is a risk?

Answer 2

Likelihood of harm arising from exposure to hazard.

Question 3

What is a risk assessment?

Answer 3

Involves identifying control measures to minimise the risk.

Question 4

Examples of control methods to reduce risk?

Answer 4

Wear PPE
Appropriate handling techniques
Aseptic techniques

Question 5

What is a log dilution?

Answer 5

Range of dilutions that differ by a constant proportion.
Each dilution acts as a stock for the next dilution
Each concentration depends on the previous ones and errors are compounded in later dilutions.

Question 6

What is a linear dilution?

Answer 6

Range of dilutions that differ by equal intervals e.g 0.1, 0.2, 0.3 etc
Add different volumes of stock solution to different volumes of solvent
Any errors only affect one concentration.

Question 7

What is the point of a standard curve?

Answer 7

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 7

What is a buffer?

Answer 7

Solution whose pH changes very little when a small amount of acid or base is added. Allowing pH of reaction mixture to be kept constant.

Question 7

What is a semi-log graph?

Answer 7

have a log scale on one axis and normal on the other.

Question 7

What is a log scale?

Answer 7

where each check mark takes you up an order of magnitude.

Question 8

What is a log-log graph?

Answer 8

Both axis are log.

Question 9

What method is used for a colorimeter?

Answer 9

Calibration with appropriate blank as a baseline.

Question 9

How does the centrifuge work?

Answer 9

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

Question 9

What are the uses of colorimeter?

Answer 9

Absorbance value - used to determine concentration of coloured solution.
Percentage transmission - used to determine turbidity such as cells suspension.

Question 9

What are the 3 types of chromatography?

Answer 9

Paper chromatography
Thin layer chromatography
Affinity chromatography

Question 10

Paper and thin layer chromatography can be used to separate what?

Answer 10

Different substances such as amino acids and sugars.

Question 11

what is affinity chromatography?

Answer 11

soluble target proteins with a high affinity in a mixture become attached to specific molecules as the mixture passes down column. Non-target with weaker affinity are washed out.

Question 12

What does the speed of the solute depend on in chromatography?

Answer 12

Differing solubility in the solvent used. More soluble components travel farthest. Less soluble components travel the least distance.

Question 13

What is gel electrophoresis meant to separate and how does it work?

Answer 13

Proteins and nucleic acids.
Move through an electric field applied to a gel matrix.

Question 14

How does native gel electrophoresis separate macromolecules?

Answer 14

By shape, size and charge. Does not denature them.

Question 14

How does SDS-page separate molecules?

Answer 14

Gives them all an equally negative charge and denatures them separating by size alone.

Question 14

Proteins can be separated from a mixture using there isoelectric points what is this?

Answer 14

Point at which a soluble protein has no net charge and will precipitate out of solution. If solution is buffered to specific pH only the proteins that have IEP will precipitate.

Question 15

How are soluble proteins separated?

Answer 15

Using Isoelectric field and pH gradient gel.
Protein stops migrating through gel at its IEP in the pH gradient because it has no net charge.

Question 16

What is immunoassay?

Answer 16

Identify specific proteins using stocks of antibodies with the same specificity known as (monoclonal antibodies)

Question 17

Antibodies can be linked to a chemical label what is that?

Answer 17

Often a reporter enzyme that produces a colour change. Fluorescence can be used.

Question 18

When is western blotting used?

Answer 18

After SDS-page electrophoresis.

Question 19

How does western blotting work?

Answer 19

Separated proteins from the gel are transferred on to a solid medium or membrane and dried. Proteins can be labelled by soaking the blot with specific antibodies. The antibodies bind to specific proteins. A second antibody with reporter enzymes are added, colour change occurs.

Question 20

Explain bright-field microscopy?

Answer 20

Used to observe whole organisms, parts of organisms, thin sections of dissected tissue or individual cells.

Question 21

Explain Fluorescence microscopy?

Answer 21

Uses fluorescent labels to bind to and visualise certain molecules or structures within the cell or tissues.

Question 22

What does aseptic techniques do?

Answer 22

Eliminates unwanted microbial contaminants when culturing micro-organisms or cells

Question 23

How are animal cells grown?

Answer 23

In medium containing growth factors from serum. Growth factors are ease in culture of most animal cells.

Question 24

In culture primary cell lines can divide a …………. Number of times.

Answer 24

Limited

Question 25

Tumour cell lines can perform …………… divisions.

Answer 25

Unlimited

Question 26

What does plating liquid microbial culture on solid medium allow?

Answer 26

Number of colony-forming units to be counted and density of cells in culture to be estimated.

Question 27

What is often needed to achieve a suitable colony count?

Answer 27

Serial dilution.

Question 28

What is a haemocytometer used for?

Answer 28

Estimate cell numbers in a liquid culture.

Question 29

What is vital staining?

Answer 29

Staining of cells to allow a viable cell count.