Cell surface membrane. Acts as a barrier (things go out and in). Smooth endoplasmic reticulum synthesises LIPIDS. (aka Fats.) [AN: See previous post, I asked about this part, yeah, probbem solved, will go back and correct in a bit.]
Magnification: Increases size, not deatil, only what you see increases in size.
Resolution: Allows you to see things close up, or closer together. Puts things into more detail.
The resolution depends on the wavelength of the illuminating source (i.e. the visible light from electrons.)
Resolution = 1/2 the Wavelength.
E.g. : A light has a wavelength of 500nm, the resolution would therefore be 250 nm.
Or: Electrons wavelength is 0.2nm, therefore, the resolution would be 0.1nm
Advantages of electron microscope:
- Greater resolution, see in more detail.
- Higher magnification (x500,000)
Disadvatages:
- Specimens are dead. *
- Artefacts (other things from outside, deposits, etc...) can be present.
- Preparation of the specimen is complex, and time consuming.
- Very expensive equiptment.
- Need a very specifically thin specimen.
*The tissue must be dead as it is in a vacuum. No oxygen, therefore, living organisms can't survive.
- Organelle shapes can be distored by this vacuum.
- See it from different angles, as it is 2D
Transmission Electron Miscroscope: Electron beam passes through specimen onto fluorescent plate onto photographic paper. 2D, and has higher resolution.
Scanning Electron Microscope: Electrons atr reflected from surface to get a 360 degree/ 3D view. Specimens can be thicker so electrons don't need to pass through. Lower resolution, 20nm. Still 10x better then light/optical, not better resoltion then a transmission electron microscope, but gives a much better image.
In the bit above, I /think/ the advantages/disadvantages are for the TEM only, as the SEM doesn't need a thin specimen, so yeah, once again, correct if wrong, or give extra info if you like. REmember, I'm only typing this up from my notes taken in class. ^___^
-Nin.
No comments:
Post a Comment