Unit 1: Key Area 1 - Lab Techniques For Biologists Glossary

Question 1

What is a hazard

Answer 1

Hazard in the lab include toxic or corrosive chemicals, heat or flammable substances, pathogenic organisms and mechanical equipment

Question 2

Define a risk

Answer 2

Risk is the likelihood of harm arising from exposure to a hazard

Question 3

What is a risk assessment

Answer 3

Risk assessment involves identifying control measures to minimize the risk

Question 4

Define control measures

Answer 4

Control measures include using appropriate handling techniques protective clothing and equipment and aseptic technique

Question 5

Define linear dilution

Answer 5

Dilutions in a linear dilution series differ by an equal interval for example 0.1, 0.2, 0.3 and so on

Question 6

Define log dilution

Answer 6

Dilutions in a log dilution series differ by a constant proportion for example 10’1, 10’2, 10’3 and so on

Question 7

Define a standard curve and why you produce one

Answer 7

Plotting measured values for known concentration to produce a line or curve allows the concentration of an unknown to be determined from the standard curve

Production of a standard curve to determine an unknown

Question 8

Describe the use of buffers to control pH

Answer 8

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

Question 9

Define colorimeter and the use to quantitfy concentrations and turbidity

Answer 9

Calibration with appropriate blank as a baseline; use of absorbance to determine concentration of a colored solution

Question 10

Explain the use of a centrifuge to separate substances of differing density

Answer 10

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

Question 11

What is paper and thin layer chromatography

Answer 11

Can be used for separating different substances such as amino acids and sugars. The speed that each solute travels along the chromatogram depends on its differing solubility in the solvent used.

Question 12

What is affinity chromatography

Answer 12

Use in separating proteins
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 13

Describe gel electrophoresis

Answer 13

Use in separating proteins and nucleic acids.

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

Question 14

Describe SDS Page

Answer 14

Separates proteins by size alone.

SDS Page gives all the molecules an equally negative charge and denatured them, separating proteins by size alone.

Question 15

Describe native gels

Answer 15

Separate proteins by their shape, size and charge.

Native gels do not denature the molecule so that separation is by shape, size and charge

Question 16

Describe isoelectric points

Answer 16

Proteins can be separated from a mixture using their isoelectric points (IEPs)
If the solution is buffered to a specific pH only the protein(s) that have an IEP of that pH will precipitate.

Question 17

Describe primary cell lines

Answer 17

Are cells taken from the body and are cultures. Can only divide by a limited number of times

Question 18

Describe tumor cell lines

Answer 18

Are cells taken from the body and are cultured. Can divide by an unlimited number of times

Question 19

What is an Isoelectric point (IEP)

Answer 19

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

Question 20

Describe what electrophoresis does and how

Answer 20

Proteins can also be separated using their IEPs in electrophoresis. Soluble proteins can be separated using an
electric field and a pH gradient. A protein stops migrating through the gel at its IEP in the pH gradient because it has no net charge.

Question 21

What are Immunoassay techniques used for

Answer 21

Immunoassay techniques are used to detect and identify specific proteins

Question 22

What do Immunoassay techniques use stocks of

Answer 22

These techniques use stocks of antibodies with the same specificity, known as monoclonal antibodies

Question 23

What is an antibody specific to the protein antigen liked to? Describe what it is?

Answer 23

An antibody specific to the protein antigen is linked to a chemical ‘label’
The ‘label’ is often a reporter enzyme producing a colour change, but chemiluminescence, fluorescence and other reporters can be used.
In some cases the assay uses a specific antigen to detect the presence of antibodies.

Question 24

Describe Western blotting

Answer 24

Western blotting is a technique, used after SDS–PAGE electrophoresis
The separated proteins from the gel are transferred (blotted) onto a solid medium
The proteins can be identified using specific antibodies that have reporter enzymes attached

Question 25

What is Bright-field microscopy commonly used for

Answer 25

Bright-field microscopy is commonly used to observe whole organisms, parts of organisms, thin sections of dissected tissue or individual cells

Question 26

Describe Fluorescence

Answer 26

Fluorescence microscopy uses specific fluorescent labels to bind to and visualise certain molecules or structures within cells or tissues

Question 27

What is the purpose of Aseptic technique

Answer 27

Aseptic technique eliminates unwanted

microbial contaminants when culturing microorganisms or cells

Question 28

What does Aseptic technique involve

Answer 28

Aseptic technique involves the sterilisation of equipment and culture media by heat or chemical means and subsequent exclusion of microbial contaminants.

Question 29

Describe a microbial culture

Answer 29

A microbial culture can be started using an inoculum of microbial cells on an agar medium, or in a broth with suitable nutrients
Many culture media exist that promote the growth of specific types of cells and microbes.

Question 30

What are animal cells grown in

Answer 30

Animal cells are grown in medium containing growth factors from serum

Question 31

What are growth factors

Answer 31

Growth factors are proteins that promote cell
growth and proliferation. Growth factors are
essential for the culture of most animal cells.

Question 32

What does plating out of a liquid microbial culture on social media allow

Answer 32

Plating out of a liquid microbial culture on solid media allows the number of colony forming units to be counted and the density of cells in the culture estimated

Question 33

What is needed to achieve a suitable colony count

Answer 33

Serial dilution is often needed to achieve a

suitable colony count

Question 34

What is required to identify and count viable cells

Answer 34

Vital staining is required to identify and count

viable cells