Two items need to be added to our list of what constitutes life for biology
All life that we know about is carbon based and all living things are composed of cells. In essence, living things are composed of little bags of chemicals.
1. All living things that we know about are composed of cells.
2. The cell is the smallest thing that we know that can perform all the functions we recognize as life. As such, the cell is the smallest unit of life.
3. All cells come from pre-existing cells.
But I'm getting ahead of myself. Cells exist on the order of micrometers. A micrometer is a thousandth of a millimeter and that's way too small to observe with just my eyes. I need help with that so let's talk about microscopes first.
When we moved from Denver to Roswell, we moved lightly. Most of our stuff, we left behind, so I've been replacing some things and reorganizing since the move. In a way, that's good because I was collecting way too much stuff. This blog is about experiencing the world out there and that means inexpensively and portably.
There is also the issue of me dumping my phone into the washing machine. Now I have a new phone. Beside the expense, moving and destroying my phone was a good thing and, to some degree, enjoyable. It let me evaluate what I have, what I need, and what I want. I've spent some time reorganizing and getting to know my set-up.
So now I have two clip-on microscopes to try out. I have my old clip-on that I brought with me. It's not terribly powerful but very portable. I keep it in the phone wallet I carry on my belt on technical hikes. The other is the much more powerful clip-on from ScienceWiz. It's a little more fiddly but the magnification is considerably more. It's still not strong enough to show a lot of very important cell structures but it's fine for field observations.
The top left is my old clip-on. The magnification wasn't expressed when I bought it and I'm still not sure how powerful it is. The other photos are of my new ScienceWiz. It's a replacement. The magnification for that microscope was expressed in the package insert and on the website. It's a fascinating piece of technology that I will discuss later in the blog.
Of course, the best thing about both in my case is that imaging is done through my smartphone so that all the functions of the phone are available, including my blog editor.
The differences between the scopes are important
The old clip-on is a reflection microscope. It shines a light onto the specimen which returns it's image to the scope to be magnified. It uses the back camera with its better magnification and resolution.
The rear camera actually has two cameras. One has a resolution of 50 megapixels and the other has a resolution of 8 megapixels. The front camera (selfies and mirror) has a resolution of 32 megapixels.
Resolution is an important limit which I will explain (and demonstrate) later. It is the total number of pixels that the camera captures in a single picture.
The main camera has an aperture of f/1.8. f stops are related to the size of the opening. In general, the smaller the number, the larger the opening, the more light is gathered, the sharper (and closer) the focus, and the shallower the depth of field, (the subject is in sharp focus but the background is more out of focus.) f/1.8 is about as low as it gets for digital cameras. Electronically, higher f stops can be simulated. T
he pixels for the primary camera are 0.61 micrometers across. That provides for decent resolution (it can resolve details in the tens of micrometers). A micrometer is a thousandth of a millimeter.
The secondary camera has an aperture of f/2.2 and a pixel size of 1.12 micrometers. It's intended for macrophotography.
The front camera is located at the top of my camera screen as a 4 millimeter wide black dot. It's used by the ScienceWiz microscope and the image is right there on the phone screen beneath the microscope. That camera has a f/2.4 aperture with 1 micrometer pixels.
It may have struck you that, maybe, the better rear cameras could be used by the stronger microscope, but then the screen would be face down. That would be practical with an add-on monitor, which is available for phones. I may consider it later. The ScienceWiz clamp-on is illuminated from above so that what you see is light after it has passed through the subject. That makes the other microscope better for opaque subjects.
The cameras on my phone (I have several) will provide up to 4x magnification. That may sound good but that is where resolution comes in. You can improve the size of an image but resolution caps clarity and detail. Optical magnification can give you sharper images. Digital magnification can not.
So, the ScienceWiz microscope provides from 200 to 400 X magnification according to the phone optics. With 4x zoom, that expands to 800 to 1600 X power. Again, zooming (digital magnification) doesn't improve resolution.
Above is a slide with a print of the letter "e" on a slide. The other two images used my old clip-on microscope. This shows the forte of this clip-on. The magnification isn't great but I can focus on small things, even opaque things like minerals or small flowers.
To get rid of the walls of the microscope shown in the bottom left, I can zoom in. The zoomed image in the lower right shows the color dots that make up the image.
As for the magnification power....
The two lines above are two millimeters apart on the ruler. In the left photo, the lines are four millimeters apart, indicating a magnification of 2x. The zoomed image makes the lines 24 millimeters apart indicating a magnification of 12x.
The top photo was taken through my old microscope. The center left is zoomed twelve times. It's a splinter carved off an old stump in the front yard. The other two images were taken with the ScienceWiz microscope and is probably similar to what Robert Hooke saw when he named cells "cells".
Several folks were said to have invented the microscope including the inventor of the telescope, Hans Lippershey, around 1600. When Robert Hooke named cells, he wasn't looking at anything alive. His specimen was a fragment of cork, which is the dead outer layer of the bark of a cork tree (a species of oak).Being dead, the cells were not doing anything and were, in fact, empty and they looked to Hooke like the cells (private rooms) of a monastery.
I have mentioned that I have several camera apps and they all have strengths and weaknesses. The one used here, the standard camera for Motorola phones will not zoom with the front camera. I have since found that a couple of my other phones will, so I'm still learning.
The resolution problem that I have repeatedly mentioned is a problem and should be kept in mind, but it's perhaps not as much of a problem as I've indicated because the phone itself has algorithms to clean up blurry photos, to an extent, and photo apps such as cameras and Google Photos give you tools to clean up and modify photos. The edges of the image in the large photo at the bottom has been sharpened.
This is my second try at a stained slide since biology labs back in the 70s. The first was bad....
These are all a classic first slide, onion skin stained with iodine. The bottom photo was made using my old microscope so it didn't surprise me that I couldn't see cells.
Cells are tiny objects in the micrometer (micron) range. Even the more powerful microscope would be hard put to see much of cells but the two photos above are a good try. The left was stained with pH indicator and, for the right, I used Betadine. Iodine stains starch blue or black and cell walls brown
If you want to try, strip the fine onion skin out from between two layers of an onion (I was frying onions and peppers for hotdogs that night). Put a drop of water on a microscope slide and place the onion skin in the drop. Add a drop of stain (food color will work, too). Slowly lay a cover slip over the specimen and if fluid seeps out, lay a piece of paper towel or tissue paper along side of the cover slip to draw the excess out.
Although you can't see the detail within the cells, you can see how the cells are lined up in rows.
There is another classic "first slide", the cheek epithelium scraping slide.
To create that, place a drop of saline on a slide (animal cells without rigid cell walls are more vulnerable to bloating than plant cells). The saline can be mixed by dissolving 1/4 teaspoon (1.5 grams) salt in 166 milliliters water. Using a toothpick, scrape the inside of your cheek repeatedly and then rub the toothpick into the saline drop. Add a drop of stain (I used blue and red food coloring for the microphotographs below.) Gently lay a cover slip over the drop
The top left photo is not zoomed. Unlike the Android camera, my other camera apps will zoom the front camera, so the second one is zoomed The blue food color worked well and I'm pleased that the nuclei showed up clearly. The other photos were zoomed about 3x. The left center, right center, and lower left photos include the red dye. The lower right photo shows what happens at maximum zoom
Optical magnification exposes detail in a photo microgram but digital zooming does not add detail. It just makes the image larger. The result is blurring.
Phone cameras have algorithms to conserve details in zoomed photos. For instance, they can take several images and layer them, sharpening edges. But even the tricks that digital cameras use can only deal with so much zoom 4x is about the limit and anything above 6x is currently useless.
With the equipment I use to keep cost low (the ScienceWiz microscope is outstanding at less than $50) and portability high, I won't be able to delve too deeply into the inner workings of the cell.
The microscope is special because it uses a spherical lens with a short focal length to augment the cell phone's camera lenses. This design has been used to provide third world countries with inexpensive, accessible, 3d printable medical equipment
For deep explorations of cell biology, I use cell models and there are three exceptional ones that I keep around:
The 3d tour of the cell video at ScienceWiz
https://sciencewiz.com/portals/cells/tour-inside-the-cell/a-tour-of-the-cell-more-advanced/
The Cell Biology Wikibook
And Kahn Academy's College and AP biology sections
Those will carry you as deeply as you could want to go into cell biology.
Some people suggest that you look at a cell like a city. I've worked in a lot of factories, so I prefer seeing a cell as a factory, a very automated factory
The walls of the factory is a membrane made of fat and phosphate that likes to align itself with the phosphate heads pointing outward into the watery environment, and the fatty tails pointing inward. It's a phospholipid bilayer because both the outer and inner environments are watery. In other words, the walls of the cell factory are fluid with things stuck in and through them (like doors and windows that only let certain things through.) Plant cells have more sturdy cell walls around the membranes that are made of stuff like cellulose. Fungus cell walls gave chitin, similar to the stuff that makes up insect bodies Bacteria can have some strange stuff.
The control center is the nucleus in eukaryotic cells. In prokaryotic cells like bacteria, everything just pretty much floats around The cell's business is programmed on long tapes (actually spirals or helixes with two outer rails that the program units are arranged between.) A complex mechanism unzips the two parts of the tape, composed of desoxyrhibonucleic acid (DNA) and use one as a template for instructions to be carried out to the rest of the cell. The mechanism has to be complex because errors in the instruction can be disastrous. The process is called "transcription". The result is a strand of ribonucleic acid (RNA) that makes it's way out of the nucleus through pores in the nuclear membrane into a series of corridors called the "endoplasmic reticulum".
What the DNA codes for is proteins. The endoplasmic reticulum, specifically the part called the rough endoplasmic reticulum, is studded with machines called ribosomes (there are also ribosomes floating around free in the gooey cell center, called the cytoplasm). Ribosomes read the RNA instructions and create proteins. Those are carried down the hall to an organelle called the Golgi Apparatus. It looks like a stack of pancakes, but the pancakes are hollow. They check the big molecules to makes sure there are no errors and then package them into neat bundles called "vacuoles" that are sent down fibers (like little railways or monorails) to their destination. That can either be to places in the cell to help produce chemicals other than proteins or to break down sugar for energy, or they can be sent outside the cell where they might act as hormones......messengers to other parts of the body.
That breaking down sugars....... that's how the cell gets energy to do things and it takes place in organelles called "mitochondria". There are complicated chains of chemical reactions that break down sugar to water and carbon dioxide and in the process add phosphate groups to ADP (adenosine diphosphate) to form adenosine triphosphate.
The machines in cells don't use electricity to operate
When a phosphate group break off ATP it releases a jolt of energy and that's what cells use for power. It's a lot safer in tiny machines than electricity or fire
Plant cells have installed an extra source of energy. They don't need to transport sugar into the cell for energy. They create their own in organelles called "chloroplasts". That's what makes plant cells green because chloroplasts use a green pigment, chlorophyll, to combine carbon dioxide and water to create sugar.
I've read that microbes can form cysts that can last in soil for a long time, so I wanted to check that out. I collected some of our desert soil in a test tube, added water, and let it sit over night. Then I took some microphotographs.
Nothing was moving but I circled some suspects. They definitely have nuclei so they're eukaryotes. That would indicate that they're protozoans but the images are too small to identify. The upper right photo shows the same scene stained differently without the marks most of the small dots are dirt particles.
I wanted to see if I could catch some of the fast division and growth of yeast cells. After 45 minutes (1 tablespoon sugar and a package of active baker's yeast in warm water) it looked like this:
But I think I waited too long. Division had slowed down. Here's a video of the action
There is some motion but it's primarily due to gravity. The slide was slanted.
But what I primarily wanted to see was if polarized light could be used as a "stain" and I was pleased at how it brought the chromosomal materials out in the cells
For those slides, I placed a polarizing filter under the microscope stage, between the lens and the front camera. Most of the cells are in interphase and the chromatids are not visible, but some of the cells are getting ready to divide and you can see the chromosomes.
Later, when I look at cell division and reproduction, I'll try this again but catch the cells earlier.
Even though I absolutely recommend that you play around with making your own slides if you're going to study biology......
Pretty pictures caught when I zoomed out and saw what the glass slide was doing with the polarized light
but you're not stuck with homebrew. Many suppliers of lab equipments also sell prepared slides. Both Home Science Tools and ScienceWiz sell sets of prepared slides. These are from the ScienceWiz animal slides collection.
And there are several sites online that provide microscopic images, including Wikimedia.
And, of course, if you want to study biology, you'll need some sources. I'm working through the Khan Academy biology sections and reading the Wikibooks in their biology section. I am very impressed with both!
But the bottomline is that there are two kinds of cells.
A prokaryotic cell is a bag of chemicals in a gelatinous goo.
A eukaryotic cell is a bag of bags of chemicals in gelatinous goo.
If you're reading this blog, you are composed of eukaryotic cells.
You might want to learn how to take care of those cells
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