Which microscope is used to see internal structures of cells in a natural state?
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Which microscope is used to see internal structures of cells in a natural state?
Microscopy
Introduction
Microscopes and lenses
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Magnification is a measure of how much larger a microscope (or set of lenses within a microscope) causes an object to appear. For instance, the light microscopes typically used in high schools and colleges magnify up to about 400 times actual size. So, something that was 1 mm wide in real life would be 400 mm wide in the microscope image.
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The resolution of a microscope or lens is the smallest distance by which two points can be separated and still be distinguished as separate objects. The smaller this value, the higher the resolving power of the microscope and the better the clarity and detail of the image. If two bacterial cells were very close together on a slide, they might look like a single, blurry dot on a microscope with low resolving power, but could be told apart as separate on a microscope with high resolving power.
Electron microscopes
Looking at the Structure of Cells in the Microscope
A typical animal cell is 10–20 μm in diameter, which is about one-fifth the size of the smallest particle visible to the naked eye. It was not until good light microscopes became available in the early part of the nineteenth century that all plant and animal tissues were discovering to be aggregates of individual cells. This discovery; proposed as the cell doctrine by Schleiden and Schwann in 1838; marks the formal birth of cell biology.
Animal cells are not only tiny, they are also colorless and translucent. Consequently; the discovery of their main internal features depended on the development; in the latter part of the nineteenth century; of a variety of stains that provided sufficient contrast to make those features visible.
Similarly, the introduction of the far more powerful electron microscope in the early 1940s required the development of new techniques for preserving and staining cells before the full complexities of their internal fine structure could begin to emerge.
To this day, microscopy depends as much on techniques for preparing the specimen as on the performance of the microscope itself. In the discussions that follow, we therefore consider both instruments and specimen preparation, beginning with the light microscope.
It shows a series of images illustrating an imaginary progression from a thumb to a cluster of atoms. Each successive image represents a tenfold increase in magnification. The naked eye could see features in the first two panels; the resolution of the light microscope would extend to about the fourth panel; and the electron microscope to about the seventh panel.
Some of the landmarks in the development of light microscopy are outlined in a chart. It shows the sizes of various cellular and subcellular structures and the ranges of size that different types of microscopes can visualize.
Which microscope best allows the observation of internal cell structures in a natural state?
Electron microscopes can allow examination of viruses and internal cell structures; whereas light microscopes are limited to objects that are 0.5 micrometers and larger.
Which type of microscope works best for seeing the internal structure of cells?
Transmission electron microscopes
What microscope would you use to see internal structures?
Electron microscopy uses electrons to see small objects in the same way that light beams let us observe our surroundings or objects in a light microscope. With EM, we can look at the feather-like scales of an insect, the internal structures of a cell, individual proteins or even individual atoms in a metal alloy.
Living Cells Are Seen Clearly in a Phase-Contrast or a Differential-Interference-Contrast Microscope
The possibility that some components of the cell may be lost or distorted during specimen preparation has always challenged microscopists. The only certain way to avoid the problem is to examine cells while they are alive, without fixing or freezing. For this purpose, light microscopes with special optical systems are especially useful.
When light passes through a living cell, the phase of the light wave is changed according to the cell’s refractive index: light passing through a relatively thick or dense part of the cell, such as the nucleus, is retarded; its phase, consequently, is shifted relative to light that has passed through an adjacent thinner region of the cytoplasm.
The phase-contrast microscope and, in a more complex way, the differential-interference-contrast microscope, exploit the interference effects produced when these two sets of waves recombine, thereby creating an image of the cell’s structure. Both types of light microscopy are widely used to visualize living cells.