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Waffle ๐ด๐ต๐ธ
11/12/2025
Biology
Microscopy and cell fractionation
64
โข
11 Dec 2025
โข
Understanding Microscopy and Cell Fractionation
Waffle ๐ด๐ต๐ธ
@amuslimah
1 / 4
Light Microscope Basics
Light microscopes are brilliant tools that use two convex glass lenses to magnify tiny objects, but they've got limits. They can only resolve images that are 0.2 micrometers apart - that's because light waves themselves restrict how much detail you can see.
You'll need to master the magnification formula: Magnification = size of image รท size of real object. This equation pops up in exams regularly, so get comfortable with it! Resolution is equally important - it's the minimum distance apart that two objects can be seen as separate things.
When you peer through a light microscope, you'll spot different structures in plant and animal cells. Plant cells show off their cell walls, chloroplasts, and large vacuoles, whilst animal cells reveal centrioles and other organelles. Some structures like ribosomes (25nm) are too small to interfere with light waves, so they're tricky to see clearly.
Quick tip: Remember that anything smaller than the wavelength of light (400nm) becomes difficult to distinguish clearly under a light microscope.
Electron Microscopes
Electron microscopes smash through the limitations of light microscopes by using electron beams instead of light. They can resolve objects just 0.1 nanometers apart - that's 2000 times better than light microscopes!
There are two main types you need to know. Transmission electron microscopes (TEM) fire electrons through ultra-thin specimens, creating detailed internal images where electron-absorbing areas appear darker. Scanning electron microscopes (SEM) bounce electrons off surfaces to build stunning 3D images based on how the electrons scatter.
Both types need a vacuum environment to work properly - air particles would knock the electrons off course. This creates some serious limitations: you can't observe living specimens, samples need complex staining (which might create artificial structures), and TEM specimens must be incredibly thin.
Remember: SEM gives you 3D surface detail, whilst TEM shows internal structures - but TEM has better resolution than SEM.
Cell Fractionation and Ultracentrifugation
Cell fractionation is like sorting your laundry, but with cell organelles! Scientists use differential centrifugation to separate different cell parts so they can study each component individually.
The process starts with homogenisation - cells get blended up in a special solution to create a mixture called homogenate. Then comes the clever bit: the homogenate gets spun in a centrifuge at increasing speeds. Heavy organelles like nuclei settle out first at low speeds, forming a pellet at the bottom.
The remaining liquid (supernatant) gets transferred to a new tube and spun faster. This time, mitochondria form the pellet. Keep increasing the speed and you'll separate out progressively lighter organelles. The initial homogenate must be kept cold, buffered, and at the same water potential as the original cells.
Key point: The process works because different organelles have different densities - heavier ones settle out at lower centrifuge speeds.
Measuring with Eyepiece Graticules
An eyepiece graticule acts like a tiny ruler built into your microscope, but here's the catch - it shows different measurements depending on which objective lens you're using. You'll need to calibrate it every single time you change magnification.
Calibration involves lining up your eyepiece graticule with a stage micrometer (a precise microscopic ruler). Count how many eyepiece graticule divisions fit into one stage micrometer division. If 35 graticule divisions equal 10 micrometers on the stage micrometer, then one graticule division equals 10 รท 35 = 0.29 micrometers.
Once calibrated, measuring becomes straightforward. Count the graticule divisions that span your specimen, then multiply by your calibration factor to get the actual size in micrometers. This technique is essential for measuring cellular structures accurately in coursework and exams.
Pro tip: Always recalibrate when switching between objective lenses - the calibration factor changes with magnification!
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Best app on earth! no words because itโs too good
Thomas R
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Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because itโs too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Understanding Microscopy and Cell Fractionation
Waffle ๐ด๐ต๐ธ
@amuslimah
Microscopy is your gateway to exploring the invisible world of cells and their tiny components. From basic light microscopes to powerful electron microscopes, these tools let scientists see structures thousands of times smaller than what your naked eye can detect.
Light Microscope Basics
Light microscopes are brilliant tools that use two convex glass lenses to magnify tiny objects, but they've got limits. They can only resolve images that are 0.2 micrometers apart - that's because light waves themselves restrict how much detail you can see.
You'll need to master the magnification formula: Magnification = size of image รท size of real object. This equation pops up in exams regularly, so get comfortable with it! Resolution is equally important - it's the minimum distance apart that two objects can be seen as separate things.
When you peer through a light microscope, you'll spot different structures in plant and animal cells. Plant cells show off their cell walls, chloroplasts, and large vacuoles, whilst animal cells reveal centrioles and other organelles. Some structures like ribosomes (25nm) are too small to interfere with light waves, so they're tricky to see clearly.
Quick tip: Remember that anything smaller than the wavelength of light (400nm) becomes difficult to distinguish clearly under a light microscope.
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Electron Microscopes
Electron microscopes smash through the limitations of light microscopes by using electron beams instead of light. They can resolve objects just 0.1 nanometers apart - that's 2000 times better than light microscopes!
There are two main types you need to know. Transmission electron microscopes (TEM) fire electrons through ultra-thin specimens, creating detailed internal images where electron-absorbing areas appear darker. Scanning electron microscopes (SEM) bounce electrons off surfaces to build stunning 3D images based on how the electrons scatter.
Both types need a vacuum environment to work properly - air particles would knock the electrons off course. This creates some serious limitations: you can't observe living specimens, samples need complex staining (which might create artificial structures), and TEM specimens must be incredibly thin.
Remember: SEM gives you 3D surface detail, whilst TEM shows internal structures - but TEM has better resolution than SEM.
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Cell Fractionation and Ultracentrifugation
Cell fractionation is like sorting your laundry, but with cell organelles! Scientists use differential centrifugation to separate different cell parts so they can study each component individually.
The process starts with homogenisation - cells get blended up in a special solution to create a mixture called homogenate. Then comes the clever bit: the homogenate gets spun in a centrifuge at increasing speeds. Heavy organelles like nuclei settle out first at low speeds, forming a pellet at the bottom.
The remaining liquid (supernatant) gets transferred to a new tube and spun faster. This time, mitochondria form the pellet. Keep increasing the speed and you'll separate out progressively lighter organelles. The initial homogenate must be kept cold, buffered, and at the same water potential as the original cells.
Key point: The process works because different organelles have different densities - heavier ones settle out at lower centrifuge speeds.
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Measuring with Eyepiece Graticules
An eyepiece graticule acts like a tiny ruler built into your microscope, but here's the catch - it shows different measurements depending on which objective lens you're using. You'll need to calibrate it every single time you change magnification.
Calibration involves lining up your eyepiece graticule with a stage micrometer (a precise microscopic ruler). Count how many eyepiece graticule divisions fit into one stage micrometer division. If 35 graticule divisions equal 10 micrometers on the stage micrometer, then one graticule division equals 10 รท 35 = 0.29 micrometers.
Once calibrated, measuring becomes straightforward. Count the graticule divisions that span your specimen, then multiply by your calibration factor to get the actual size in micrometers. This technique is essential for measuring cellular structures accurately in coursework and exams.
Pro tip: Always recalibrate when switching between objective lenses - the calibration factor changes with magnification!
We thought youโd never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
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Is Knowunity really free of charge?
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Most popular content: Microscope
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Most popular content
English - inspector calls quotes and analysis
Quotes from every main character
English Literature10
Can't find what you're looking for? Explore other subjects.
Students love us โ and so will you.
4.9/5
App Store
4.8/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because itโs too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because itโs too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user