Can You See Cells With A Microscope?

K&f concept 2026-08-04 01:25:00 0 Comments

Cells and microscopes

Cells are tiny! Cell diameters are typically measured in micrometers µ‍‍. Objects of this size are too small to be seen with the unaided eye.

To see and study cells, scientists use microscopes. These powerful tools magnify objects, allowing them to be seen up close. Microscopes can also capture images, called micrographs.

All living organisms are made up of cells. Cells are the smallest part of a living organism and are around 0.01 mm - 0.03 mm long. To look at a cell close up a microscope needs to be used.

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.

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What can be observed

Light microscopes can be used to visualize living cells.
Scientists use light microscopes to study cell structures and to observe cell movements and interactions.
For example, light microscopes can be used to observe cell division, the behavior of microorganisms, or changes in cancer cells.
With a good 100x, you can expect to see bacteria, red blood cells, and plant cells.
You can see onion cells with an even lower powered microscope.
Many types of cells need to be stained to make them visible.
Yes, you can even see cells with 100x (objective and eye-piece), some cells can even be seen under 40x (objective and eye-piece).
However, bacterial cells would require more, you'd need 1000x (objective and eye-piece) if you want to see their morphology.

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Magnification and resolution

Magnification power: Magnification power is not everything, in my microbiology lab we used 100x. as a maximum.
Resolution: What counts is resolution, a good 100x will beat any poor 300x everytime. There is no point looking at a big fuzzy blob, a small, clear image is so much better.
Total magnification: To see an object, the eye piece lens and the objective lens magnification are multiplied together to give the total magnification.
Formula: Total magnification = eye piece lens magnification × objective lens magnification.
Example: For example: 10 × 20 = 200. Magnification = 200.

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Light microscopy

Light microscopes work by shining white light (or sometimes single coloured light) against an object, and letting it bounce off a mirror through our magnification lens.

The way we see things is by light reflecting of of it into our eyes. Lenses take reflected light and make the image appear bigger.

We can only see things by bouncing light off them and then into our eyes. Lenses help us focus light so we can see smaller things, but evsntually, the things you're looking at are smaller than the wavelengths of light.

Light itself has a size and you can't bounce it off things that are smaller than it and get a good picture.

In order for the "reflection" to work the wavelength of the light has to be smaller than the object. This isn't a problem with anything we interact with in the normal world because everything is massive compared to wavelengths of visible light.

The problem is as you try to view something small, like cells, you need increasing smaller wavelengths of light. For most cells visible light is fine as they're still quite big.

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Wavelength limits

Light is a waves that have larger wavelength then the size of a atom.
The wavelenght of visible light is 380-740 nm.
A larger atoms have a diameter of 0.5 nm and the smaller hydrogen have a diameter of 0.05nm.
When a wave interact with object that is smaller then the wavelength it will diffract.
So light start to bend around object and other effect so the result is that you cant use light with microscopes for sizes below 200nm.
So light can pass around a small object and you cant see it is a way to look at it.
The minimum object you can see depend on the wavelength.
The light microscope can resolve details 0.2 μm apart.

Staining and living cells

Specimens are often stained with chemical dyes to make cell parts visible.

Different components of the cell can be selectively stained. Specific molecules can be located in cells by fluorescence microscopy. Antibodies can be used to detect specific molecules.

Living cells are seen clearly in a phase-contrast or a differential-interference-contrast microscope.

Fluorescence microscopes are a type of light microscope. A fluorescence microscope is a type of light microscope that creates brightly-colored images. The colors come from fluorescent (light-producing) dyes that are used to label different molecules in the specimen.

Scientists use fluorescence microscopes to observe the role of specific cell components in cellular processes, and to locate specific proteins in the cell.

Images can be enhanced and analyzed by electronic techniques. Imaging of complex three-dimensional objects is possible with the optical microscope. The confocal microscope produces optical sections by excluding out-of-focus light.

Electron microscopes

An electron microscope focuses beams of electrons on specimens instead of visible light.
Electron microscopes can visualize details at a much smaller scale compared to light microscopes.
For example, electron microscopes can capture detailed images of the structures inside of cells.
The electron microscope resolves the fine structure of the cell.
If you use electrons as the illumination instead of light you can ave a resolution smaller then 0.05 nm.
All particles can be looked at as both particles and waves.
The wavelength of a electron will depend on the momentum and when used in electron microscopes the momentum depend on the voltage you use.
At 200 000 v the wavelength of a electron is 0.0025nm and that is smaller then a atom.
So in some condition you can see individual atoms with a election microscope.

Electron microscopy and nonliving cells

However, because of the way specimens have to be prepared for viewing, electron microscopy can only be used to see nonliving cells.

A electron microscope needs the specimen to be placed in a vacuum to be able to magnify the object, because electrons move around easier in a vacuum. Since there is no oxygen in a vacuum, the cell can't survive.

Biological specimens require special preparation for the electron microscope. Microscopy depends as much on techniques for preparing the specimen as on the performance of the microscope itself.

Development 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.

Specific macromolecules can be localized by immunogold electron microscopy. Negative staining and cryoelectron microscopy allow macromolecules to be viewed at high resolution. Multiple images can be combined to increase resolution.

Scanning and transmission electron microscopes

Scanning electron microscopes: SEMs are used to show 3D images of a specimen’s surface.
Surface features: SEMs allow scientists to observe the overall shape and surface features of cells.
Example: For example, with an SEM, scientists can see outer cell structures such as the flagella.
Transmission electron microscopes: TEMs are used to visualize a thin cross section (slice) of a specimen.
Internal structures: TEMs allow scientists to see detailed images of organelles and other structures inside of cells.
Example: For example, with a TEM, scientists can see the inner membranes of mitochondria, details of the nucleus, and parts of the cytoskeleton.

Onion and cheek cell observation

Carefully cut an onion in half (or ask an adult). Peel a thin layer of onion (the epidermis) off the cut onion.
Place the layer of onion epidermis carefully on the glass slide, and cover with a cover slip.
Stain the layer of onion with food colouring.
Rub the tip of a new, clean soft-ended cotton bud against the side of your cheek.
Dip the cotton bud in the disinfectant (solution), and dispose in a sealed plastic bag in the bin.
Stain the slide by rubbing it with a cotton bud dipped in food colouring.
Rub the cotton tip (with your cheek cells on it) against the food colouring.

Focusing the specimen

Move the stage (the flat ledge the slide sits on) down to its lowest position.
Place the glass slide onto the stage. Be careful pushing it under the clips that the cover slide doesn't move or crack.
Select the lowest power objective lens.
Turn the coarse focus knob slowly until you are able to see the cells.
Turn the fine focus knob slowly until the cells are in focus and you can see them clearly.
Repeat steps 1-5 using the higher power magnification to see the cells in more detail.