AH Bio - 1.1 Laboratory techniques for biologists

Affinity

the degree to which a substance is attracted and tends to bind to another substance

Affinity chromatography

a technique used to separate and purify proteins based on a specific binding interaction between an immobilised ligand and its binding partner

Antigen

a specific protein with which antibodies bind to in an immune response

Aseptic technique

procedures in place to prevent contamination, including sterilising equipment and work surfaces

Bright-field microscopy

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

Buffer

a solution used to set and maintain a particular pH

Centrifugation

a process that uses centrifugal forces to separate components of different densities in a mixture

Chromatography

a technique used to separate different substances; it has a stationary phase (for example, paper or gel) that the mobile phase (for example, a solvent) moves through, carrying the substance being examined; different distances are moved by substances of different solubility

Colorimeter

a device used to measure the absorbance of a specific wavelength of light by a solution

Culture media

a nutrient-rich growth medium providing the basic requirements for cell growth (amino acids, glucose, salts, water, as well as specific growth factors for animal cell lines)

Fluorescence

the emission of light of a different wavelength to that which was absorbed

Fluorescence microscopy

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

Gel electrophoresis

technique used to separate samples of nucleic acid and protein by size; introduced to a gel, they move through it due to an electric current; smaller fragments move further than larger fragments

Growth factors

proteins that promote cell growth and proliferation

Ligand

a substance that can bind to a protein

Haemocytometer

microscopic grid used to estimate the total number of cells within a sample (originally used to count blood cells)

Hazard

anything that poses a potential risk or threat to an individual or the environment

Immunoassay

technique used to detect and identify specific proteins; antibodies linked with reporter enzymes, for example, cause a colour change in the presence of a specific antigen

Inoculum

starting material used to grow a culture from, for example a bacterial culture

Isoelectric point (IEP)

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

Linear dilution series

a series of dilutions that differ by an equal interval, for example 0.1 M, 0.2 M, 0.3 M, and so on

Log dilution series

a series of dilutions that differ by a constant proportion, for example 10-1, 10-2, 10-3, and so on

Monoclonal antibodies

stocks of identical antibodies that are specific to a particular antigen

Native gel electrophoresis

does not contain SDS and does not denature the molecule, so proteins are separated by their shape, size and charge

Pathogenic

causing disease

Primary cell lines

a culture of cells isolated directly from animal or plant tissues; they have a finite lifespan and limited expansion capacity

Reporter enzyme

an enzyme linked to an antibody specific to a protein antigen; they are used in immunoassay techniques

SDS-PAGE

electrophoresis in which the gel contains SDS, which gives all the molecules an equally negative charge and denatures them, separating proteins by size alone

Serum

vitally important as a source of growth factors, hormones, lipids and minerals for the culture of cells

Standard curve

a graph that can be used to determine the concentration of an unknown solution

Supernatant

the liquid that lies above a solid residue or pellet in centrifugation

Turbidity

a measure of the degree to which a fluid loses its transparency due to the presence of suspended particles or cells in suspension

Vital staining

a technique in which a harmless dye is used to stain either living tissue cells or dead cells for microscopical observation to allow a viable cell count to be made

Western blotting

an analytical technique used to identify and locate specific proteins in a sample of tissue homogenate or extract based on their ability to bind to specific antibodies