Bright Field And Fluorescence Microscopy Flashcards
What happens in Bright-field microscopy?
a sample is mounted on a slide and illuminated from below.
Light is transmitted through the specimen to the objective lens (which magnifies the image) and then to the eyepiece at the top of the microscope where the image is observed.
The image of the sample that is produced is usually darker than the background which appears bright.
What is often carried out on samples before Bright-field microscopy? Why is this done?
Samples are often stained before being viewed using a bright field microscope to increase contrast.
What does fluorescence microscopy allow?
particular protein structures to be visualised.
What is a fluorescent molecule?
A fluorescent molecule is one which absorbs a specific wavelength of light then emits a different (longer) wavelength. This means that it absorbs light of one colour and emits light of a different colour.
What happens during fluorescence microscopy?
specific protein structures have fluorescent markers added to them. The cells can then be placed on a slide and the protein structure visualised using a fluorescence microscope.
What is immunofluoresecence? Describe this.
when antibodies are used to fluorescently tag protein structures.
A primary antibody, which is specific to the protein being visualised, is introduced to a cell sample.
A secondary antibody, attached to a fluorescent tag, is then added which binds to the primary antibody.
Describe how a fluorescent microscope works.
the light passing through the sample first passes through a filter which only lets through light at a specific wavelength that corresponds to the fluorescent marker being used.
When this light hits the fluorescent marker, it fluoresces and emits light of a different wavelength.
The second filter separates emitted light from the light first passed through the specimen and the fluorescing regions of the sample can be viewed in the microscope.
