DNA Extraction
from wheat germ
Protocol
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Step #1
• Obtain a numbered 50 ml
conical vial with 10 ml of
water.
• Write your number
here:________
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Step #2
• To the tube with 10 ml
water add 1g (1 pinch)
of raw wheat germ.
– The wheat germ should
settle to fill 1/2 the
cone
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Step #3
• Cap the tube and
vigorously shake to
mix for about 30
seconds.
• What do you think
the shaking is doing
to the wheat cells?
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• After shaking - let
the cell walls settle
to the bottom
– What’s in the cloudy
solution?
– Where is the DNA at
this point?
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Step #4
• Using a transfer pipet
add 3 ml of 25% dish
soap to the tube with
water and wheat germ.
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Steps #5-6
• Cap the tube and
slowly invert several
times to mix (DO
NOT SHAKE).
Loosen the cap
slightly before placing
tube in the hot water
bath.
• Heat at 65°C for 5
minutes.
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• What do you think the soap will do?
• How will the hot water bath help?
• Bonus question:
– Why does washing your hands with soap and
hot water kill bacteria on your skin?
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Step #7
• While the tubes are
heating label a 1.7 ml
eppendorf tube with
your initials.
• Carefully open the epi
tube and place it into
the rack
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Steps #8-9
• Before removing your
tube from the 65°C water
fill a transfer pipet with
3ml of alcohol.
• Bring the 50 ml conical
tube back to your table
and as soon as possible
add the 3ml of alcohol to
the tube.
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Step #10
• Watch the DNA rise out
of the green soap layer
and into the alcohol layer.
• What color is DNA??
– What color do you think
YOUR DNA is?
– Why?
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Step #11
• After waiting a few
moments to allow the
DNA to precipitate
remove the DNA
using an inoculation
loop and place in your
eppendorf tube. Try to
avoid any wheat germ
debris that is present.
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Step #11 cont.
• Spinning the loop will
help get the DNA off
• Make sure to close the
epi tube securely
(you should hear it
“click”)
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Congratulations!
• You have just done something that
scientists do everyday in the lab!
• Your DNA will last you for years – it’s
very stable when stored in isopropanol
• SOME RULES:
– Your DNA tube should be put away during
school - other teachers will confiscate it if
you disturb their class!
– You must show your parents at home your
DNA and tell them what you learned!
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Review:
• We extracted DNA from wheat germ
• And discovered that the color of DNA is …
WHITE!
• No matter what organism it comes from, DNA
in a tube looks the same!
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We ALL have white DNA!!
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