Investigating DNA
Aim: To extract and examine DNA.
Materials: As per page 40.
Method: As per page 40.
Results:
As it can be seen in the picture, the DNA appeared to be a white coloured and looked like threads floating in the liquid.
Discussion:
1. Explain why each of the following were used in the extraction process.
• Detergent
Detergent was used as detergent has the ability to break down the plasma membrane of the peas cells. This then allows the meat tenderiser to enter the cells and allows the DNA to exit the cells.
• Meat tenderiser
The meat tenderiser contains an enzyme that is able to break down proteins, so its job is to break down the nucleus to release the DNA and also to break the enzymes in the cells that break down the DNA
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An error could be that the detergent wasn’t mixed thoroughly enough. This could affect the results as if the detergent isn’t mixed properly, than the cell membranes could not have been broken down very well. This would mean that then DNA wouldn’t be able to come out of the peas. To minimise this in the future, it can be made sure that the detergent is give a good stir when it is poured into the pea mixture. Another error could have been that the alcohol was poured straight into pea mixture and was mixed in with the pea and water mixture instead of forming a layer on top of the mixture. This affected the results as alcohol is less dense than the water and pea mixture so the DNA should rise through to the alcohol layer, but without the alcohol layer there will be no movement of DNA. To minimise this in the future, it is recommended that you hold the test-tube on an angle and gently pour the alcohol down the side of the test-tube. Another error could be that the stirring time of five minutes for the meat tenderiser wasn’t timed. This could affect the results as if the meat tenderiser isn’t properly mixed in it could mean that it hasn’t being able to break down the nucleus to release the proteins and even if it has done that it could not have broken down the enzymes that break down DNA that escapes the nucleus. This would mean that there would be no DNA leaving the cells. To minimise