Extraction of DNA From a Strawberry

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Extraction of DNA From a Strawberry
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Directions for completing lab.

• 1. Crush the strawberry in a plastic storage
  bag.
• Squeeze air out of bag.
• Follow the demonstration of technique given by
  Mr. Cooney.
• This step should take _at_ 3 minutes.

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Directions for completing lab. (contd)

• 2. Open bag.
• Pour in 10 ml of the extraction buffer that is
  found in the front of the room. Use the plastic
  micropipette that is provided.
• Remove air from the bag and reseal.
• With your fingers or the palm of your hand, mix
  the buffer with the strawberry.
• Avoid creating foam, so proceed slowly with this
  step.
• Continue for _at_ 2 minutes.

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Directions for completing lab. (contd)

• 3. Empty the contents of the bag into a funnel
  that is lined with cheesecloth.
• Pour the mixture slowly.
• Allow the contents to drip slowly through the
  cheesecloth into a collecting test tube.
• Take your time - _at_ 10 minutes.
• When finished, discard the cheesecloth into a
  garbage can, being careful not to drip any on the
  floor.
• Throw out the plastic bag.

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Cheesecloth traps large debris and material.
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Directions for completing lab. (contd)

• 4. When instructed to do so, measure out 10 ml
  of ice cold ethanol obtained from the freezer.
• Pour the ethanol into an ice cold graduated
  cylinder.
• Return the unused ethanol to the freezer.

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Directions for completing lab. (contd)

• 5. Tilt the test tube containing the strawberry
  mixture.
• Gently and slowly pour the cold ethanol into this
  test tube.
• The ethanol will sit on top of the strawberry
  solution.
• The area where the strawberry and the ethanol
  meet is known as the interface.
• Observe the DNA that has appeared, especially
  near the interface.

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Directions for completing lab. (contd)

• Using the yellow inoculating loop, gently twist
  the loop and gather the DNA that has formed.
  After observing, discard the DNA in the sink.

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Directions for completing lab. (contd)

• 7. You will repeat the process with the remainder
  of the alcohol after stirring (according to Mr.
  Cooneys directions).
• 8. When finished, take this DNA and all of the
  contents of the test tube an pour it down the
  drain in the sink. Wash the test tube and return
  all materials to their proper place.

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Why strawberries?

• Strawberries are soft and easy to pulverize.
• Produce their own pectinase and cellulase
• Cell walls are made of cellulose
• Enormous genomes.lots of DNA!
• Octoploidy (sometimes called polyploidy), eight
  sets of chromosomes.
• Humans are diploid.

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Why strawberries? (contd)

• Detergent dissolves the phospholipids, especially
  those found in the cell membranes.
• Membranes also in the Golgi Apparatus,
  mitochondria, SER, RER, lysosomes, etc.
• Cell parts and molecules are liberated.

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Why strawberries? (contd)

• Filtering will separate the large parts (debris)
  from the soluble (disolved) parts (DNA and
  proteins).
• DNA is insoluble in ice cold ethanol, so it
  falls out and clumps together (precipitates).
• Salt in the detergent will prevent the proteins
  from precipitating out with the DNA- - you will
  only see the DNA.

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THE END