ameliorate = improve, enhance
corpuscle = a minute body or cell in an organism, especially a red or white cell in the blood
nonius scale = vernier scale = google it if you don't know
Basic Shit:
When we use the light microscope we'd better prepare a microscopic slide. That's a small rectangular piece of glass (carrier glass) on which we put what we want to examine (often liquid stuff like blood or milkshake) and then put another thinner piece of glass called coverslip.
We can also apply a protective or preservative treatment to our stuff, or even stain it so we can see clearer and in color.
Our microscope uses two sets of lenses, the first, called oculars magnifies 10 times and the second set (objective lenses) can change (often among 4x, 10x, 40x and 100x). The total magnification is the product of the two (add 'zero' to the objective lens magnification, 40x, 100x etc).
We fix our slide on the stage of the microscope, adjust so we see clearly and enjoy!
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Resolution is the minimum distance between two nearby objects in which we can discriminate they are apart.
Magnification and resolution are different.
For example, if with the naked eye we see two stars that are close to one another as one, a shitty telescope might show us a bigger picture of the same one fuzzy bright thing (magnification but not greater resolution), whereas, using a quality telescope of high resolution with the same magnification we can tell they are two stars, not one star, they are TWO DIFFERENT STARS.
Our eyes' resolution is around 0.1mm.
A good light microscope has a resolution of around 1μm.
Since we are talking distances in the range of the wavelength of visible light (that's 0.4-0.7μm) an optical microscope can't visualize structures smaller than 0.5μm ( I don't understand why 0.5 and not larger than 0.7μm).
To increase the resolution of the greatest magnification we apply oil (immersion oil) between the lens and the microscopic slide. The oil increases the refraction index N of the light and for a reason I didn't quite get it helps.
We often add colouring-matter to increase the contrast.
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What to be careful of using the microscope:
- Use immersion oil ONLY with the larger magnification.
- Coverslip of the microscopic slide on the top.
- If you wanna magnify more and switch lens you may want to readjust the diaphragm and the light brightness.
- Don't use the coarse focus knob when rolling the 'oil immersion lens'. It's a delicate guy. Also, always wipe the lens properly off the oil.
Diameter of the field of view:
To have a sense of the sizes of what we look we can use a microscopic slide with crossed hairs and a nonius (or vernier) scale. We just measure the distance between two opposing points in the periphery of the 'circle' we see in the microscope.
Make sure the diaphragm is completely open.
Remember, these distances/sizes can be in μm.
1000μm = 1mm (=10^-6m) .
Now, our measuring tool (the nonius scale) is too big for the largest dry magnification (400x) so we have to calculate the diameter of the field of view from the previous (probably 100x ) measurement. Basically just divide it with how many times larger is the new magnification (in this case 4x so divide by 4).
Optical Depth
is the elevation of the stage at which we can sharply see (focus on) our specimen. A good way to determine where to set our stage height is to try discriminate which of two crossed hairs is on the top, using the middle or largest dry magnification. When we can clearly see that, we have found our optical depth.
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Determination of the real size
That's cool! As long as we have the diameter of field of view, we can just estimate how many times of our thingy make that diameter and divide with that.
For example: If I have a cell of 'width' 1/6 and 'height' 1/3 of my FOV, and my Field Of View is 350μm, my cell's 2-dimensions will be 350/6 and 350/3 μm.
We can calculate the diameter of our hair :D
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We'll have to make drawings of our findings. I'll find it hard to not put eyes and boobs on my cells but science ain't promiscuous, or that's what she wants us to believe.
Anyway, the drawings are in scale, so we have to carefully calculate how many micrometers each of our on-drawing centimeters is. That number over one is our scale.
Εach 1cm is 10.000 μm.
Example: I draw a circle of diameter 2cm to represent a circle of 116μm.
My scale is 2cm/116μm = 20.000μm/116μm = 172/1
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Now, to the lab session on mitosis
Cell division is called mitosis.
btw, meiosis is splitting cells in 2 without duplicating the DNA to create gametes (sperm or eggs)..
Mitosis is only one of the three phases in a cell cycle.
The major phases of a cell cycle:
1. Interphase: The time in between dividing. Cell growth, replication of DNA, and preparation of mitosis.
2. Mitosis: That's how unicellular organisms reproduce asexually and how multicellular organisms grow and repair themselves. In mitosis the nucleus divides.
3. Cytokinesis: The cytoplasm divides and two plasma membranes form to eventually form two new cells.
Interphase is the longest phase. In interphase the genetic material (chromatin) will appear grainy and indistinct inside the nucleus. Chromosomes are not distinct.
Then, cells enter the prophase of mitosis. The chromosomes begin to condense and become visible as darkly stained structures. They appear clearly until the end of telophase.
Look carefully at this figure of Mitosis. Please motherfuckers do it. It's the most nice and relevant I found.
In plants, mitosis occurs at specific sites of the plant.
This formative plant tissue is called meristem. It's usually made up of small cells capable of dividing indefinitely to similar cells or cells that differentiate.
Meristems can be found in the stem and root tip.
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