Cells and Proteins - Laboratory Techniques

Question 1

What can present a hazard in a lab?

Answer 1

Substances, organisms and equipment

Question 2

What do hazards in a lab include?

Answer 2

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

Question 3

Define risk?

Answer 3

The likelihood of harm arising from exposure to a hazard

Question 4

What does a risk assessment involve?

Answer 4

Identifying control measures to minimise the risk

Question 5

What are examples of control measures?

Answer 5

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

Question 6

Describe linear dilution?

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

Describe log dilution?

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 can the concentration of an unknown be determined from the standard curve?

Answer 8

By plotting measured values for known concentrations to produce a line or curve

Question 9

What are buffers used for?

Answer 9

To control pH

Question 10

How do buffers control pH?

Answer 10

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

Question 11

How are colorimeters used to quantify concentration?

Answer 11

Absorbance to determine concentration of a coloured solution using suitable wavelength filters

Question 12

How are colorimeters used to quantify turbidity?

Answer 12

Use of percentage transmission to determine turbidity, such as cells in suspension

Question 13

What is the separation technique centrifuge used for?

Answer 13

To separate substances of different density

Question 14

How does centrifuge work?

Answer 14

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

Question 15

What separation technique is used for separating different substances such as amino acids and sugars?

Answer 15

Paper and thin layer chromatography

Question 16

How does paper and thin layer chromatography work?

Answer 16

The speed that each solute travels along the chromatogram depends on its differing solubility in the solvent used

Question 17

How does affinity chromatography work?

Answer 17

A solid matrix or gel column is created with 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

Question 18

How does gel electrophoresis work?

Answer 18

It separates proteins and nucleic acids.

Charged macromolecules move through an electric field applied to a gel matrix

Question 19

How do native gels work?

Answer 19

They do not denature the molecule (protein) so that separation is by shape, size and charge

Question 20

How does SDS-PAGE work?

Answer 20

It gives all the molecules an equally negative charge and denatures them, separating proteins by size alone