Cells under the microscope Flashcards
What is meant by Resolving Power?
“Resolution”
The ability to distinguish two close objects
The maximum resolving power depends on the wavelength of illumination
What is the wavelength of visible light?
What is its resolving power?
Visible light has a wavelength of 400-700nm
Visible light can resolve objects about 200nm apart
Which micoscope would be used to resolve atoms?
An electron microscope
In a 200kV electron microscope the electron’s wavelength is 3 picometers
What is the minimum resolving power of a light microscope?
200nm is the minimum resolveable by the light microscope
What is the minimum resolving power of electron microscopes?
0.2nm is the minimum resolvable by electron microscopes
[…] cell can reveal subceullular structures
Staining cells can reveal subcellular structures
What is indirect immunofluorescnece?
A method of localizing specific proteins in the cell
What is the specificity and sensitivity of indircet immunofluorescence?
- Specificity - uses an antibody to the protein of interest (the antigen)
- Sensitivity - Fluorescence
- A molecule is fluorescent if it absorbs light of one wavelength and then emits light of a different (longer wavelength)
What are the steps of Immunofluoresence?
- Primary antibodies are introduced into the cell which bind to the designated antigen
- Marker coupled secondary antibodies are introduced, which subsequently bind to the primary anitbodies
When tagging two organelles in the cell, which antibodies have to be from different species and which can be from the same species?
The primary antibodies have to be from different species, while the secondary antibodies can be from the same species
What is the sensitivity and specificity of Green fluorescent protein (GFP)?
- Sensitivtiy - GFP Fluorescence
- Specificity - GFP protein “fusion”
Where does GFP come from?
Comes from the jellyfish Aequoria victoria
Which fluorescent protein colors come from mutated GFP?
Cyan and Yellow come from mutated GFP
What are the pros of electron microscopy?
Much better resolution than light microscope (more detail)
What are the cons of the electron microscope?
- Much more effort to get a 3D view of the cell
- More difficult to label specific proteins
- Cannot be used on live cells (imaging is done in a vacuum)
- Highest resolution is tricky because damage to sample caused by electrons
What are the key features of the Plasma Membrane?
- Seperates the cell from the environment
What are the key features of the Endoplasmic reticulum (ER)?
- Primary site for synthesis of lipids, membrane proteins, and secreted proteins
- Sections of ER with ribosomes bound are called “rough ER”
What are the key features of the Golgi Apparatus?
- Performs modifications on secretory proteins
- Central sorting station for vesicle trafficking
