There are many similarities between SEMs and TEMs. The components of these two high-resolution microscopes are very similar. Each has an electron source/gun that emits an electron stream towards a sample in a vacuum, and each contains lenses and electron apertures to control the electron beam and capture images.

A light microscope is used to view the details of the surface of a cell as it cannot be viewed in detail by the transmission microscope. b. A light microscope allows visualization of small living cells, which have been stained and cannot be viewed by scanning electron microscope.

Light Microscope vs Electron Microscope. Light microscopes and electron microscopes both use radiation – in the form of either light or electron beams, to form larger and more detailed images of objects (e.g. biological specimens, materials, crystal structures, etc.) than the human eye can produce unaided.

The main difference between light microscope and electron microscope is that beam of electrons is used for magnifying the image of an object while visible light is used in the light microscope to magnify images of tiny areas of materials or biological specimens.

There are three basic types of microscopes: optical, charged particle (electron and ion), and scanning probe. Optical microscopes are the ones most familiar to everyone from the high school science lab or the doctor’s office.

What is the purpose of the lenses in a compound light microscope? There are several purposes of the lenses in a compound light microscope they are to bend light and make objects appear larger than they really are. Light microscopes today are more modern , so they can magnify objects up to 1,000 times the size.

With light microscopy, one cannot visualize directly structures such as cell membranes, ribosomes, filaments, and small granules and vesicles. Using an appropriate staining technique, however, makes aggregates of these smaller structures or the regions they occupy visible by light microscopy.

Light Microscopes can enlarge images up to 1,500 times their original size. They can be used to view living or nonliving objects. It can magnify an image up to 100,000 times or more and it’s resolution is up to 1,000 times greater than a light microscopes.

The specimens used for light microscopy are usually stained to increase their contrast prior to observations. The blood cells were stained with hematoxylin and eosin (H&E). With H&E staining, it is possible to observe large organelles, such as the cell nucleus, which stains a dark purple.

Upon viewing the bacteria under the microscope, you will be able to identify the bacteria based on a wide variety of physical characteristics. This mainly involves looking at their shape and size. There are a wide variety of different shapes, yet the three main types are cocci, bacilli, and spiral.

Even with a microscope, bacteria cannot be seen easily unless they are stained. The largest bacteria, such as Bacillus megaterium, can also be seen at 400X. Most other bacteria require 1000X magnification. Algae and protozoa are best viewed in a wet mount without staining.

If you have an unknown bacteria and you want to identify it, you’ll typically perform a gram stain and then observe the colony appearance and the individual features. At that point, you can say you have, for example, a gram-negative, aerobic streptobacilli.

The three basic bacterial shapes are coccus (spherical), bacillus (rod-shaped), and spiral (twisted), however pleomorphic bacteria can assume several shapes. Cocci (or coccus for a single cell) are round cells, sometimes slightly flattened when they are adjacent to one another.

spherical

Examples of Bacteria:

• Lactobacillus acidophilus found in yogurt.
• Staphylococcus aureus found on our skin.
• Escherichia coli found in our gut to aid in digestion.
• Staphlyococcuspneumoniae which causes pneumonia.
• Clostridium botulinum which can contaminate canned goods and cause botulism. Related Links: Examples.