Cells, Microscopes, and Organelles

Cells, Microscopes, and All the Organelles, and you can draw pictures!! ..**

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  • Created on: 05-08-09 15:41
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Light Microscopes
Light Microscopes use visible light to magnify images.
Light has its limits with:
Any specimen that has properties less than 250 nm apart cannot be resolved and is
seen as one or not seen entirely.
And a maximum magnification of ×1500
Scanning Electron Microscope (SEM) & Transmission Electron Microscope (TEM)
SEM's use electromagnets to create electrons that scan over the surface of the specimen,
this produces a 3D image of the cell ultrastructure.
To use an electron microscope effectively, the specimens need to be:
Extremely thin
Coated with chemicals to make important parts of the specimen show up.
Coated with metals (usually gold) so that the electrons are not absorbed by the
specimen and are reflected off to produce an image on the computer screen.
Completely dehydrated so that no water molecules will interrupt the vacuum.
Dead because the chemicals would harm the specimen otherwise.
An Electron Microscope has a greater resolution than a light microscope because
electrons have a shorter wavelength.
Resolution: The minimum distance between two points at which they are visible as
two separate points. If they cannot be resolved they will be seen as one.
Magnification: Enlarging the specimen.

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The Animal Cell
Incl. Cell Ultrastructure
An Animal cell is a very simple structure, with a number of different organelles. Animal, and
Plant cells are Eukaryotic Cells. Their nuclei contain the DNA, and they have a complex
system of organelles.…read more

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Cell Ultrastructure
Eukaryotic Cells Under the Electron Microscope
Cell Surface Membrane/ Plasma Membrane:
The cellsurface membrane is the plasma membrane that
surrounds the cell and forms a boundary between the cell
cytoplasm and the environment. It allows different
conditions to be allowed inside and outside the cell. The
membrane is a bilayer of phospholipid molecules with
intrinsic and extrinsic protein in varying shapes and sizes
inbetween the phospholipids. These control the entry and
exit of substances through diffusion, active transport, and
osmosis.…read more

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This is the largest of the organelles, and has a number of
o The Nuclear Envelope is a double membrane, in
which the outer membrane is continuous with RER,
whereas the inner membrane controls the entry and
exit of substances.
o The Nuclear Pores allow ribosomes, and the large
molecule of RNA to leave the nucleus.
o The Nucleoplasm makes up the bulk of the nucleus.
o The Chromatin is the DNA found within the
Nucleoplasm.…read more

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Lysosomes are formed from the vesicles produced in the
golgi apparatus. They contain enzymes that can break up a
cell by releasing their contents.
These are fingerlike projections of the epithelial cell that
increase its surface area to allow more efficient
absorption.…read more


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