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Slide 1

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Gel Electrophoresis…read more

Slide 2

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What is it?
· Gel Electrophoresis is a type of
· Chromatography is the term used to describe
the separation of chemicals, or in this case the
separation of different pieces of DNA based
on their length.…read more

Slide 3

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The Process..
· DNA strands are cut into fragments using Restriction Enzymes.
· The fragments are placed into wells of an Agar Tank using a Micropipette.
· The fragments are colourless but can be dyed using: ethidium bromide
(highly visible under UV light) or individual strands of DNA can be `labelled'
from the beginning, using Radioactive Isotopes (visible under x-ray once
the experiment is complete).
· DNA is found to carry a negative charge because of the oxygen they carry,
so when an electric current is passed through the Agar, the fragments
move towards the positive electrode (anode).…read more

Slide 4

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The smaller DNA fragments move faster and therefore
further down the gel towards the anode, whereas the
larger fragments are slower therefore stay closer to the
· The Process the fragments move by is called `Reptation'.
· This difference in speed of movement allows the fragments
to be separated by size.
· Photographic paper is placed on the finished gel in the dark
and the DNA will show up as Dark Bands (when `labelled').…read more

Slide 5

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1. Name the 6 main stages of Gel
Electrophoresis. (6)
2. Name the type of Enzyme used to `cut' the
DNA strands. (1)
3. Name the dye often used in Gel
Electrophoresis. (1)
4. Describe where the different lengths of DNA
fragment would be found in the Agar gel at
the end of Gel Electrophoresis. (2)…read more

Slide 6

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1. -DNA strands cut by restriction enzymes.
-Fragments placed in Agar Gel.
-Fragments of DNA dyed or `labelled'.
-Electrical current passed through the gel.
-Fragments move towards the positive electrode.
-Photographic paper makes the DNA visible.
2. Restriction Enzymes
3. Ethidium Bromide
4. Longer strands ­ Top of Agar (Closer to Cathode)
Smaller strands ­ Lower on Agar ( Closer to Anode)
/10…read more


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