The use of the electron microscope has advanced our understanding of cell biology further than the light microscope. Discuss." The definition of a microscope is that it is an instrument for viewing objects that are too small

Heather Sanders – Biology Coursework : Ms Belbin

“The use of the electron microscope has advanced our understanding of cell biology further than the light microscope. Discuss.”

The definition of a microscope is that it is an instrument for viewing objects that are too small to be seen easily by the naked eye. Microscopes have been around since the end of the first century and have become an essential instrument within early and modern-day science.

Below is a timeline or the innovation of the microscope from when it was first invented, to today.

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From this timeline, it is clear to see that the development to the microscopes that we are familiar with today was a gradual process, occurring over a century to evolve. We see how microscopes have progressed to the level that we can now see 3D images of cells and microscopic organisms.

Light Microscopes:

Invented in the 18th century, the light microscope was the beginning of what we now use to view microscopic cells and organisms. It is commonly used in small laboratories among the world and also in many secondary schools.

You would need to use ...

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Light Microscopes:

You would need to use a light microscope to view plant and animal cells, but you would only be able to see the outline of a bacteria cell.

A light microscope uses several lenses and a light source to view cells. A light microscope must gather large amounts of light from a dim, distant object; therefore, it needs a large objective lens to gather as much light as possible and bring it to a bright focus. The eyepiece of the microscope then magnifies that image as it brings it to your eye.

(Bill Indge, Martin Rowland, Margaret Baker – AQA Biology Spec. A )

Electron Microscopes:

Electron microscopes were developed due to the limitations of Light microscopes, which are limited to 500x or 1000x magnification and a resolution of 0.2 micrometers.

In the early 1930's this limit had been reached and there was a scientific desire to see the fine details of the interior structures of organic cells (nucleus, mitochondria, inside the nucleus itself, nucleolus). This required 10,000x plus magnification which was just not possible using Light Microscopes.
The Transmission Electron Microscope (TEM) was the first type of Electron Microscope to be developed and is patterned exactly on the Light Microscope except that a focused beam of electrons is used instead of light to "see through" the specimen. It was developed by Max Knoll and Ernst Ruska in Germany in 1931.
Next came the Scanning Electron Microscope (SEM) in 1942, with the first commercial instruments becoming available around 1965. Its late development was due to the electronics involved in "scanning" the beam of electrons across the sample.

Due to the Electron microscopes, scientists were able to the see cells and other microscopic organelles in much high detail and allowed them to understand functions within the cells fully, giving many of the modern understandings their foundations.

(www.uni.edu/CMRAcfem)

Comparison of Light and Electron Microscopes:

(www.mos.org/sin/SEM)

Technological Advancements:

Light Microscope …

The use of the early microscopes proved that disease and illness were not caused by an act of God, but in fact by small bacterium that were discovered under a light microscope. This was thanks to Van Leeuwenhooke was an amateur scientist who outdid his contemporaries by discovering ways to make superior lenses. These lenses magnified up to 200x when other common lenses only magnified 50x. Because of his superior magnification, Leeuwenhoek was the first to see bacteria, protozoa and spermatoza.
The use of light microscope helped early scientists discover that all living organisms were made up of individual cells. The scientist to discover this was Robert Hooke. Hooke made his discovery while studying a sample of cork. The structural mesh he saw reminded him of the small monastic rooms called cells.
Marcello Malpighi was the first to prove a controversial theory of the time, that the blood circulates in a circular motion from the heart around the body and back to the heart. It was not until 1660 when Malpighi actually saw capillaries, the microscopic connection between arteries and veins, that this theory was accepted.
Scientists have now developed a light microscope that can view particles just 100 nanometres across, using lasers, a metal coating and water. This shows how diverse microscopes have become and also how they will continue to evolve.

Before discoveries like Malpighi's, Hooke's and Leeuwenhoek's the microscope was doubted as a tool of scientific discovery. People did not realize that magnification might reveal structures that had never been seen before. The idea that all life might be made up of tiny components unseen by the unaided eye was simply not even considered.

(www.invsee.asu.edu/Modules/ size&scale/unit3/microscopy

www.newscientist.com/search/articals/2490/lightmicro)

Electron Microscopes …

It allowed researchers for the first time to view viruses directly, instead of merely suspecting their existence and guessing about their structure and behaviour. Because of this discovery, researchers could begin formulating medicines to combat a wide range of serious viral diseases, including polio and influenza.
Scientists have used electron microscopy to observe DNA, the chemical instruction code that controls human heredity. As researchers have begun to unlock the secrets of this genetic code, an immense new field of medicine has opened up, such as genetic engineering which in turn has already led to the creation of new drugs.

Also, scientists were able to prove the existence of DNA. Researchers had theorised its existence since 1871, not until the development of the electron microscope could scientists prove

Electron microscopes have helped to aid the controlling or even eliminating inherited diseases. Scientists are now able to use developed methods applied to DNA to aid diseases such as Downs Syndrome and FILL CRAP IN HERE!!!!!!!!!!!
Electron microscopes help researchers study newly discovered biological developments in more detail, such as aiding with cancer studies, in the hope that one day, a cure will be discovered.

"Only the electron micro-scope could provide convincing evidence that viruses were distinct entities present in infected tissue or purified intact there from. . . .The electron micrograph [photograph] of a virus was its official, definitive portrait." Nicolas Rasmussen, Science historian 1945

(www.bookrags.com/researchtopics/microscopes)

Conclusion: Light Microscope vs. Electron Microscope

“Using an instrument the size of his palm, was able to study the movements of one-celled organisms. Modern descendants of van Leeuwenhoek's light microscope can be over 6 feet tall, but they continue to be indispensable to cell biologists because, unlike electron microscopes, light microscopes enable the user to see living cells in action. The primary challenge for light microscopes since van Leeuwenhoek's time has been to enhance the contrast between pale cells and their paler surroundings so that cell structures and movement can be seen more easily. To do this they have devised ingenious strategies involving video cameras, polarized light, digitizing computers, and other techniques that are yielding vast improvements in contrast, fuelling a renaissance in light microscopy.”

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The light microscope was the underlying foundations for later development and was the spark that started the fire of microscopy within science.

However the electron microscopes have helped develop a further understanding for the world around us and we have been able to make some remarkable discoveries and evolutions in science. Without the electron microscopes, we would not have the standard of living that we do today, many human beings would be dieing unnecessarily of disease such as polio and influenza.

The enhancement of the electron microscope has saved lives and will continue to save others in the future.

Therefore, neither the light nor electron microscope has developed further, only our understanding has. Whether this is done to one or the other is not the case as many modern discoveries are being made with both microscopes to the current day in all fields of scientific developments. Electron microscopes have developed our detailed understanding of cell components and light microscopes have monitored cell movements and behaviour, so each balance. This is because you can discover as many cell components as you want, what they’re made up, their chemical formulas and the likes with an electron microscope, but how are you meant to understand them fully unless you study their movements with a light microscope. Therefore advance human understanding of cell biology; the key component is not just an electron or a light microscope, but both.

Bibliography:

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