Investigating Mitosis

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Why, when investigating mitosis is the sample cut from the root tip?
Because it is where growth occurs, and therefore mitosis occurs
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What temperature should the water bath be?
60 c
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How are root tips observed?
Put in a tube of 1 M hydrochloric acid, and in a water bath of 60C, incubate for 5 minutes, rinse with cold water using a pipette, and leave to dry on a paper towel. Cut 2mm from the endand use a mounted needle to spread the cells out, add stain, pu
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Cont.
push on the cover slip, and observe with an optical microscope.
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Why do you push the coverslip?
It makes it thinner, so light can pass through it.
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How do you observe cells using an optical microscope?
Clip the prepared cell onto the stage, choose the lowest power objective lens, bring the stage up to just below the lens using the coarse adjustment knob, looking through the eyepiece continue to adjust until it is roughly in focus, adjust the focus
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Cont.
using the fine adjustment knob until the image is clear, if you need more magnification, swap to a higher power objective lens and readjust
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What is the mitotic index?
Proportion of cells undergoing mitosis
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How do you calculate mitotic index?
Mitotic Index = Number of cells with visible chromosomes/total number of cells
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What is used to calculate the size of cells?
Graticule and micrometer
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What is the eyepiece graticule?
Fitted onto the eyepiece, like a ruler, has numbers but has no units
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What is the stage micrometer?
Placed on the stage, has accurate scale with units, and is used to work out value of divisions on the eyepiece graticule
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How is the value of divisions on the eyepiece graticule calculated?
Line it up with the stage micrometer,
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Other cards in this set

Card 2

Front

What temperature should the water bath be?

Back

60 c

Card 3

Front

How are root tips observed?

Back

Preview of the front of card 3

Card 4

Front

Cont.

Back

Preview of the front of card 4

Card 5

Front

Why do you push the coverslip?

Back

Preview of the front of card 5
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