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Cells, microscopes and creepy crawlies

Cells, microscopes and creepy crawlies. And all the other things you can’t see!. How small are they really?. E. coli: 2-3 μ m. Influenza virus: 0.130 μ m OR 130 nm. 1000 μ m!!!. Let’s have a closer look!!!. Onion cell: 250-400 μ m. Red Blood cell: 8 μ m.

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Cells, microscopes and creepy crawlies

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  1. Cells, microscopes and creepy crawlies And all the other things you can’t see!

  2. How small are they really? E. coli: 2-3 μm Influenza virus: 0.130μm OR 130 nm 1000 μm!!! Let’s have a closer look!!! Onion cell: 250-400 μm Red Blood cell: 8 μm

  3. Field of view • When you look in a microscope the circle of light that you see is called the ‘field of view’ • But how do we know how small a cell/specimen really is? • It depends on the magnification • As you increase the magnification the field of view decreases

  4. Measuring a cell! 1,600 μm Field diameter ÷ no. cells ÷ 3 1,600 μm 1000 μm!!! ≈ 533 μm

  5. Measuring a cell! Field diameter ÷ no. cells 4,000 μm 1,600 μm 400 μm Low 4,000 μm ÷ 2 ≈ 2,000 μm ≈ 800 μm 1,600 μm ÷ 2 Medium ≈ 200 μm 400 μm ÷ 2 High

  6. Measuring your own specimens! • We’re going to look at a few specimen • Draw what you see • Write down the magnification • Low = 4 × 10, Medium = 10 × 10, High = 40 × 10 • Guess how many of them you could fit side by side • Use the formula to work out how long / wide your specimen are! • Then we’ll come back to our tables to discuss what we found

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