1) The document provides instructions for extracting DNA from bananas through mixing mashed banana with a saltwater and soap solution, filtering the mixture, and adding pineapple juice and ethanol to precipitate out the DNA. 2) It explains that DNA is a molecule found in cell nuclei that has a double helix structure formed from two intertwined strands bound by nucleobases. 3) In 1953, Watson and Crick discovered the double helix structure of DNA with help from Franklin's X-ray crystallography photographs, though Franklin did not receive a Nobel Prize since she died before the award.

1. Extracting DNA fromfruitsExtracting DNA fromfruits

2. ● Verify to have all the materials before starting the experiment (pic.
1).
● Melt the salt (about 10 g) in 100 ml of water (pic. 2).
● Add a teaspoon (about 10 g) of liquid soap (pic. 3 and 4).

3. ● Stir slowly, without making foam, which may hinder the contact
between the solution and the banana (pic. 5 and 6).
● Mash 100g of banana (pic. 7 and 8).

4. ● Pour the mush into the solution (pic. 9).
● Wait for 20 minutes.

5. What isWhat is DDNNAA??

6. ● DNA or desoxyribonucleic acid is a
molecule content in the cell nucleus.

7. ● If we could look DNA closely, we would
discover that this molecule is composed
by two strands which, joined together, fold
up forming a double-helix similar to a
spiral stairs.
● If we could look DNA closely, we would
discover that this molecule is composed
by two strands which, joined together, fold
up forming a double-helix similar to a
spiral stairs.

8. ● The rungs of this stair correspond to chemical
substances called nucleobases which form a chemical
bond two by two.
● DNA can be compared to an important instruction
book which contains genetic informationuseful for
cells to “make”differents chemicals molecules known
as proteins.

9. WHO DISCOVERED DNA?WHO DISCOVERED DNA?
● In 1953, the
scientists J.
Watson and F.
Crick discovered
the double-helix
structure of
DNA.
● They were
helped by the

10. Unfortunately,
Franklin did not
recived Nobel Price
for medicine in 1962
with her collegues
Watson and Crick
because she died
before the
assignment of the
Prize, but it is
necessary to

11. COME BACK TO OURCOME BACK TO OUR
EXPERIMENT!!!EXPERIMENT!!!

12. ● After 20 minutes, filter the mixture (pic. 10-12).

13. ● Wait until the mixture goes through the filter (pic.13
and 14).
● Take a sample of 5 ml from the filtered mixture with a
syringe (pic. 15 and 16).

14. ● Move the liquid into the test tube, avoiding making foam (pic.
17).
● Add 2 ml of pineapple juice using another syringe (pic. 18).
● Turn upside down the tube 2 or 3 times to facilitate the
mixing of the liquids (pic. 19).

15. ● Add 10 ml of ethyl alcohol (pic. 20 e 21).
● Wait a few minutes and the ball of DNA will emerge
and, using a magnifying glass you'll be able to see it.
(fig. 22-24).