1. Key Area 1- Lab techniques for biologists

Question 1

define a hazard

Answer 1

a source of potential harm

Question 2

what are the 3 main types of hazards?

Answer 2

substances, organisms and equipment

Question 3

define a risk

Answer 3

the likelihood of harm arising from exposure to a hazard

Question 4

what are the 3 main control measures

Answer 4

1. appropriate handling technique
2. protective clothing and equipment
3. aseptic technique

Question 5

what is a risk assessment

Answer 5

involves identifying control measures to minimise the risk

Question 6

what are the 4 hazards in the lab?

Answer 6

1. toxic or corrosive chemicals
2. heat or flammable substances
3. pathogenic organisms
4. mechanical equipment

Question 7

What are linear dilutions

Answer 7

they differ by an equal interval

Question 8

What is a standard curve and what is it used for?

Answer 8

Is produced in order to determine the concentration of a solute in an unknown solution

Question 9

What piece of equipment is used to determine the absorbance of a substance or its turbidity ?

Answer 9

a colorimeter

Question 10

Define turbidity

Answer 10

Proportional to the density of cells in the culture

Question 11

What is a buffer?

Answer 11

Solutions to control pH so that changes in pH don’t act as a confounding variable

Question 12

What is the function of centrifugation

Answer 12

To separate substances of differing densities

Question 13

What is the use of paper and thin layer chromatography?

Answer 13

To separate different substances such as: amino acids and sugars

Question 14

What does the speed that each solute travels along the strip depend on? (2 reasons)

Answer 14

its solubility in the chromatography solvent and its differing affinity

Question 15

What is affinity chromatography used for?

Answer 15

To separate target proteins from a mixture of proteins

Question 16

How are target proteins separated in affinity chromatography?

Answer 16

Soluble target proteins with high affinity for the specific molecules in the solid gel column (antibodies or ligands) attach to them. Non-target proteins with weaker or no affinity are washed out, target proteins can be washed out separately producing a more pure sample.

Question 17

What is the use of gel electrophoresis

Answer 17

Separates proteins and nucleic acids

Question 18

Describe the process of gel electrophoresis?

Answer 18

Charged macromolecules (proteins and nucleic acids) move through an electric field applied to a buffered gel matrix (polyacrylamide gel electrophoresis or PAGE)

Question 19

What separates proteins by their shape, size and charge

Answer 19

Native gels

Question 20

Why does SDS-PAGE separate proteins by size alone?

Answer 20

It contains Sodium Dodecyl Sulfate (SDS) which denatures molecules passing through it and gives all molecules present a negative charge thus separating proteins only by size

Question 21

Define a proteins isoelectric point (IEP)

Answer 21

Is the pH value at which a protein is electrically neutral with surface charges that are balanced. If the soultion is buffered to a specific pH, only the proteins that have t

Question 22

Effect of IEP on proteins in solutions

Answer 22

If the solution is buffered to a specific pH, only the proteins that have an IEP of that pH will precipitate.
+ Proteins can also be separated using their IEPS in electrophoresis

Question 23

What is the use of immunoassay techniques?

Answer 23

To detect and identify specific proteins

Question 24

What are stocks of antibodies with the same specificity?

Answer 24

monoclonal antibodies

Question 25

What are antibodies specific to the protein antigen linked to?

Answer 25

A chemical ‘label’, often a reporter enzyme that produces a colour change

Question 26

When is western blotting used?

Answer 26

After SDS-PAGE electrophoresis

Question 27

How is western blotting carried out?

Answer 27

Separated proteins from the gel are transferred (blotted) onto a solid medium. The protein can then be identified by using specific antibodies which have reporter enzymes attached

Question 28

What is bright field microscopy used for?

Answer 28

To observe whole organisms, parts of organisms, thin sections of dissected tissues or individual cells

Question 29

What is fluorescence microscopy used for?

Answer 29

Uses specific fluorescent labels to bind to and visualise certain molecules or structures within cells or tissues

Question 30

What is the purpose of aseptic technique?

Answer 30

Eliminates unwanted microbial contaminants when culturing micro-organisms or cells

Question 31

What is the equipment needed to start a microbial culture?

Answer 31

An inoculum of microbial cells on an agar medium or in a broth with suitable nutrients

Question 32

what are the nutrients/ growth factors from required for animal cells to grow?

Answer 32

glucose, fatty acids, amino acids etc

Question 33

Difference between primary cell lines and tumour cell lines

Answer 33

Primary cell lines can divide a limited number of times whilst tumour cell lines can perform unlimited divisions.

Question 34

What type of dilution is often needed to achieve a suitable colony count?

Answer 34

serial dilution

Question 35

What are haemocytometers?

Answer 35

Microscopic grids used to estimate cell numbers in liquid culture

Question 36

What is required to identify and count viable cells?

Answer 36

Vital staining