BIOLOGY DEMONSTATIONS

       Seeing human DNA

Aim: To extract DNA from human saliva.

Concept: 
 when dish wash liquid is added to the saliva it opens the cells that lines the cheeks. It opens the nucleus that holds the DNA. The salt makes everything to clump to
Ethyl alcohol helps to precipitate the DNA strands from the solution.DNA is not soluble in alcohol, so it forms a solid where the alcohol and salt water layers meet. Most other substances from your cheek cells stay dissolved in the salt water layer. The white strings and clumps you see are thousands of DNA molecules clumped together. Single DNA molecules are far too small to see with the naked eye.

Materials required: 100 ml beaker , salt, ethyl alcohol,  dish wash liquid , glass rod

Procedure:
1. Wash your mouth clean.
2. Collect your saliva in the beaker
3. To the saliva add a drop of dish wash liquid.
4. Mix the solution using glass rod
5. Add a pinch of salt.
6. To this now add ethyl alcohol and mix
7. Observe


Observation: There is a clumpy white substance seen floating in the solution.

Application : collection and storage of blood sample is difficult hence saliva can be used instead of blood for DNA testing 

No comments:

Post a Comment