ANHB3323 Lecture Notes - Lecture 2: G0 Phase, Photon, Antigen
3 Jun 2018
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LECTURE TWO: Microscopy and the Cell Cycle
Microscopy:
• Essential for cell biology
• 1 micrometre (um) = 1/1000 of a mm
• Cell sizes range from 5-100um
• Average cell nucleus → around 5um diameter
• Useful cellular ruler → red blood cell → 8um in diameter
Viewing Cells – Resolving Power:
• Human eye → down to 0.2mm
• Light microscope → down to 0.2um
• Electron microscope → down to 0.2 nm
• What shines on the sample
o Light microscopy
▪ Combined light wavelengths (e.g. white light, colour or
transmission microscopy)
▪ Specific light wavelengths (fluorescence microscopy)
• Epifluoresence
• Confocal
• Super-resolution
o Electron microscopy (conducted in vacuum)
▪ Electrons
Fixation:
• Start of microscopy
• Fixation = immediate stop of living processes in cells or tissues
• Main job → preserve structure
• Fixation blocks the degradation enzymes (DNAses, RNAses and
proteases) as well as prevent rotting by bacteria
Methods of Fixation:
• Physical
o Dessication
o Heat
o Freezing
• Chemical Methods
o Aldehydes
o Formaldehydes
o Paraformaldehyde
o Glutaraldehyde
• Solvents
o Methanol
o Ethanol
o Chloroform
o Acetone
• Acids
o Picric acid
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