The main difference between a microscope and a magnifying glass is as follows
The resolution of the microscope depends on the wavelength of the light used, the electron microscope began to appear in 1933 is due to the use of a much shorter wavelength than the visible light of the electron beam as a light source, so that the resolution it can achieve than the optical microscope greatly improved. And the different light source, also determines the electron microscope and optical microscope
A series of differences.
According to the differences in the imaging principle of the electron beam and the role of the sample on the different ways, the modern electron microscope has been developed to form a number of types, at present * commonly used is the transmission electron microscope and scanning electron microscope, the former can be in the range of 1,000-1,000,000 times the total magnification of the range of changes, the latter can be in the total magnification of the 20-300,000 times the total magnification of the changes between. This experiment focuses on the preparation of samples for the two types of microscopes, transmission electron microscope and scanning electron microscope.
Second, the equipment
1. Strain Escherichia coli (Escherichia coli, Escherichia coli) slant.
2. Solutions or reagents Amyl acetate, concentrated sulfuric acid, anhydrous ethanol, sterile water, 2% sodium phosphotungstic acid (pH 6.5-8.0) aqueous solution, 0.3% polyvinyl formaldehyde (dissolved in trichloromethane) solution, cytochrome c, ammonium acetate, plasmid pBR322.
3. Instruments or other paraphernalia Ordinary optical microscope, copper mesh, porcelain funnel, beaker, flat dish, sterile burette, sterile tweezers, lancet, slides, ** counting plate, vacuum coater, critical point dryer and so on.
Operation steps
Handling of metal mesh
Samples for optical microscopy are placed on slides for observation. However, in transmission electron microscopy, since electrons cannot penetrate the glass sheet, only mesh material can be used as a carrier, usually called carrier mesh. The carrier mesh can be divided into many different specifications due to different materials and shapes, of which the * commonly used is the 200-400 mesh (number of holes) copper mesh. Copper mesh should be treated before use to remove the dirt on it and keep it clean, otherwise it will affect the quality of the supporting film and the clarity of the specimen photos. The copper mesh used in this experiment is 400 mesh, which can be treated in the following way: firstly, bleach it with amyl acetate for a few hours, then rinse it with distilled water for several times, and then bleach it in anhydrous ethanol for dehydration. If the copper mesh by the above method is still not clean, can be used to dilute concentrated sulfuric acid (1:1) immersed in 1 ~ 2 minutes, or in 1% NaOH solution boiled for several minutes, rinsed several times with distilled water, placed in anhydrous ethanol dehydration, to be used.
