1.1 laboratory techniques for biologists

Question 1

define hazard

Answer 1

anything that can cause harm in the laboratory/field

Question 2

hazards in the lab (5)

Answer 2

toxic/corrosive chemicals
heat
flammable substances
pathogenic organisms
mechanical equipment

Question 3

define risk

Answer 3

the likelihood of harm arising from exposure to a hazard

Question 4

define risk assessment

Answer 4

identifying control measures to minimise risk

Question 5

control measures in the lab (4)

Answer 5

appropriate handling techniques
protective clothing
protective equipment
aseptic techniques

Question 6

linear dilution series

Answer 6

concentrations differ by an equal interval
0.1, 0.2, 0.3 etc.

Question 7

logarithmic dilution series

Answer 7

concentrations differ by a constant proportion
10⁻¹, 10⁻², 10⁻³ etc.

Question 8

use of a standard curve to determine an unknown concentration

Answer 8

plot measured values for known concentrations
formation of a standard curve
determine unknown concentrations

Question 9

purpose of a buffer

Answer 9

allow addition of acid/alkali without significant effect on pH, so pH is kept constant

Question 10

use of a colorimeter

Answer 10

calibration with an appropriate blank as a baseline
use of absorbance to determine the concentration
use of % transmission to determine turbidity

Question 11

use of centrifuge

Answer 11

separates by density
more dense components in the pellet
less dense components in the supernatant

Question 12

use of paper and thin layer chromatography

Answer 12

separates different substances
the speed which a solute travels depends on its solubility

Question 13

affinity chromatography

Answer 13

separates different proteins
solid matrix with specific molecules is created
target proteins (high affinity) bind
non-target proteins (weak affinity) are washed out

Question 14

gel electrophoresis

Answer 14

separates proteins and nucleic acids
an electric field is applied to a gel matrix and charged macromolecules migrate through the gel

Question 15

native gels

Answer 15

separate proteins by size, shape and charge
native gels do not denature the molecule

Question 16

SDS-PAGE

Answer 16

separates proteins by size only
all proteins are denatured and given an equal negative charge

Question 17

define isoelectric point

Answer 17

the pH at which a soluble protein has no net charge and will precipitate out of solution

Question 18

IEP electrophoresis

Answer 18

separates proteins by their isoelectric points
uses an electric field and pH gradient
proteins will stop migrating through at their IEP as it has no net charge

Question 19

define monoclonal antibodies

Answer 19

stocks of antibodies with the same specificity
the antibodies are linked to a chemical label

Question 20

western blotting

Answer 20

used after SDS-PAGE
separated proteins are transferred onto a solid medium
specific antibodies with reported enzymes attached identify the proteins

Question 21

bright-field microscopy is used to observe

Answer 21

whole/parts of organisms
dissected tissue
individual cells

Question 22

fluorescence microscopy

Answer 22

fluorescent labels bind to molecules/structures within cells/tissues, allowing visualisation

Question 23

purpose of aseptic techniques

Answer 23

eliminate unwanted microbial contaminants when culturing micro-organisms/cells

Question 24

examples of aseptic techniques

Answer 24

sterilisation (of equipment/media) by heat or chemical means

Question 25

growth factors

Answer 25

contained in serum
proteins that promote cell growth and are essential for the culture of most animal cells

Question 26

primary cell lines

Answer 26

perform limited divisions

Question 27

tumour cell lines

Answer 27

perform unlimited divisions

Question 28

haemocytometers

Answer 28

used to estimate cell numbers
multiply by 10,000

Question 29

vital staining

Answer 29

to identify and count viable (live) cells
dead cells cannot be distinguished from live cells without staining