Glossary

Antibodies

(Singular, antibody) Large Y-shaped proteins with two identical binding sites produced by the immune system of vertebrate animals in response to infections. Antibodies recognise antigens on the surface of cells and bind to specific epitopes. They are used in many cell biological techniques.

Confocal microscopy

A specialised type of fluorescence (light) microscopy that allows taking images in thin sections through a cell which can be assembled into a 3D image.

Double immunolabelling

Immunolabelling that uses two antibodies directed against two different proteins inside the same cell. The localisation of both proteins can be visualised simultaneously using secondary antibodies carrying different labels.

Electron microscope

Microscope that uses a beam of electrons instead of light, and magnetic fields as lenses. Electron microscopes have a much higher resolution than light and fluorescence microscopes and allow one to study cellular ultrastructure.

Electron microscopy

A type of microscopy that uses an electron beam to visualise the samples.

Fixed cells

Fixation is a process in which cells are first killed, then their structure is preseved by applying a fixative like formaldehyde. It is often followed by permeabilisation, which allows molecules like antibodies access to the cytoplasm.

Fluorescence microscope

Specialised type of light microscope which detects fluorescence, given off by fluorophores which were used to label the sample. Fluorescence microscopes use filters so samples are only illuminated with light of specific wavelengths.

Fluorescence microscopy

A specialised type of light microscopy that uses a fluorescence microscope and filters to illuminate the sample with light of a specific wavelength.

Fluorescence Recovery After Photobleaching

Abbreviated as FRAP. Specialised application of fluorescence microscopy that allows studying the movement of proteins in living cells.

Fluorescence Resonance Energy Transfer

Abbreviated as FRET. Specialised application of fluorescence microscopy that allows studying how close two proteins are inside a (living) cell.

Fluorescent dye

Fluorescent molecules that can be used to label structures in a cell. They can be cell-permeable.

Fluorescent indicator

Fluorescent molecule that changes its characteristics (e.g. the brightness) depending on environmental factors, for example the concentration of a certain ion. It is often cell-permeable and can be used to monitor changes of e.g. the concentration of an ion inside cells.

Fluorophore

Alternative name for fluorescent molecule. Chemicals which emit fluorescent light of a particular colour when illuminated with light at specific wavelengths.

Immunolabelling

Technique that allows the labelling of specific proteins inside a cell or on its surface using antibodies.

Light microscope

Microscope that uses visible light to illuminate a sample and glass lenses to focus and magnify the image. Also called an optical microscope.

Light microscopy

A type of microscopy that uses visible light to visualise the samples.

Magnification

Term that describes by how much a structure has been enlarged.

Micrograph

Image taken with a microscope.

Organelles

Membrane-bound components of eukaryotic cells, specialised to carry out particular functions.

Resolution

The smallest distance between two objects that can be distinguished by a particular type of microscopy.

Scale bar

Visual representation of a known length, typically a line, that is included in a microscopic image to provide a reference for the size of objects in the image. It helps to establish the magnification and the actual size of structures being viewed.

Scanning electron microscope

A type of electron microscope used to study the surface of intact cells and tissues. A sample is coated with a thin metallic layer that deflects an electron beam onto a detector.

Staining

Technique used during sample preparation in microscopy to increase the contrast of structures inside cells. Different stains are used in the different types of microscopy.

Super-resolution microscopy

A specialised type of fluorescence (light) microscopy that allows taking images with a better resolution than that of normal fluorescence (light) microscopy (up to ~25 nm vs. 200 nm).

Transmission electron microscope

A type of microscope used to study inside of cells and tissue sections. The sample is stained to increase the contrast of cellular structures when they are exposed to an electron beam. A transmission electron microscope is also known as a TEM.