key area 1

Question 1

linear dilution

Answer 1

Concentrations of each solution are separated by an equal interval e.g. 0.1, 0.2, 0.3 (does not have to be a factor of 10

Question 2

log dilution

Answer 2

Dilutions in a log dilution series differ by a constant proportion, for example 10-1, 10-2, 10-3

Question 3

standard curve

Answer 3

Method that is used to determine the concentration of a solution by using known concentrations which are measured and graphed

Question 4

buffers

Answer 4

Sterile solutions which control pH.

Question 5

colorimeter

Answer 5

Device that is used to measure the absorbance of a specific wavelength of light by a solution.

Question 6

absorbance

Answer 6

How much light has been absorbed by the sample.

Question 7

transmission

Answer 7

How much light passed through the sample without being absorbed. % transmission can calculate the turbidity of a substance

Question 8

centrifugation

Answer 8

A process which uses centrifugal forces to separate components of a mixture.

Question 9

pellet

Answer 9

Forms at the bottom (higher density materials) after centrifugation.

Question 10

supernatant

Answer 10

liquid at the top (lower density materials) after centrifugation.

Question 11

chromatography

Answer 11

A set of techniques which separates the components of a mixture.

Question 12

thin layer chromatography

Answer 12

Used for separating amino acids and sugars, a strip of absorbent material on a non reactive binding, the amount they travel depends on the solubility and how much they bind to the stationary phase

Question 13

affinity chromatography

Answer 13

Relies on the binding interactions between a protein and an immobilised ligand. Use to separate proteins.

Question 14

paper chromatography

Answer 14

uses pigments in a leaf, polar components will bind to cellulose fibres quickly and don’t travel up the paper

Question 15

electrophoresis

Answer 15

A process which applies an electric current across a gel to separate components of a mixture.

Question 16

native gel electrophoresis

Answer 16

Type of electrophoresis which separates proteins by their shape, size and charge.

Question 17

SDS page electrophoresis

Answer 17

Type of electrophoresis which separates proteins by size alone.

Question 18

isoelectric point

Answer 18

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

Question 19

bright field microscopy

Answer 19

Commonly used to observe whole organisms, parts of organisms, thin sections of dissected tissue or individual cells. uses stains to improve clarity

Question 20

fluorescent microscopy

Answer 20

Specific fluorescent labels to bind to and visualise certain molecules or structures within cells or tissues.

Question 21

haemocytometer

Answer 21

A device which allows an estimation of the concentration of cells in a sample to be made.

Question 22

aseptic techniques

Answer 22

Used to eliminate unwanted microbial contaminants when culturing micro-organisms or cells.

Question 23

examples of aseptic techniques

Answer 23

blue flame on the loop, chemicals to clean work surface, flame the glass neck of bottles

Question 24

microbial culture

Answer 24

Can be started using an inoculum of microbial cells on an agar medium, or in a liquid broth with suitable nutrients.

Question 25

primary cell line

Answer 25

A culture which will only divide a limited number of times and then die

Question 26

tumour cell line

Answer 26

A culture which does not have limitation, and will grow and divide indefinitely in cell culture.

Question 27

typical cell culture

Answer 27

Contains water, salts (Murashige and Skoog salts for plants), amino acids, vitamins and glucose.

Question 28

complex cell culture

Answer 28

Contains growth factors (proteins) from serum to promote cell growth and division (proliferation)

Question 29

vital staining

Answer 29

Estimates of cell counts can be made can be made using trypan blue dye, which is absorbed by dead cells. Required to identify and count viable cells.

Question 30

immunoassay

Answer 30

Techniques which use antibodies linked to reporter enzymes to cause a colour change in the presence of a specific antigen.

Question 31

monoclonal

Answer 31

Type of antibodies can be used to detect both the presence and concentration of a protein within a solution.

Question 32

western blotting

Answer 32

Allows scientists to identify specific proteins which are present in a cell sample. Technique used after SDS-PAGE electrophoresis where the membrane is then probed for the protein of interest using a specific antibody that is linked to a detectable label.