3.9 DNA Extraction

Question 1

What are the steps for DNA extraction?

Answer 1

-Grind sample in a pestle and mortar
-Mix sample with water, detergent and salt
-Heat at 60°C for 15 minutes in a water bath
-Cool the mixture for 5 minutes
-Add protease enzyme
-Add a layer of ethanol on top of the sample
-The DNA will be seen as white strands forming between the layer of sample and layer of alcohol.

Question 2

Why should you grind a sample in a pestle and mortar for DNA extraction?

Answer 2

To break down the cell walls

Question 3

Why should you add salt to a sample for DNA extraction?

Answer 3

To break down the hydrogen bonds between the DNA and water molecules.

Question 3

Why should you mix a sample with detergent for DNA extraction?

Answer 3

To break down the cell membrane, releasing the cell contents (including DNA) into the solution.

Question 4

Why should you add protease to the sample for DNA extraction?

Answer 4

This will break down the histones, allowing the DNA to uncoil

Question 4

Why should you heat the sample at 60°C for DNA extraction?

Answer 4

DNase enzymes, which would otherwise start to cut the DNA into fragments, are denatured.

Question 5

Why should you cool down the sample for 5 minutes for DNA extraction?

Answer 5

To slow down the breakdown of DNA/denaturing of enzymes

Question 6

Why should you add a layer of ethanol on top of the sample for DNA extraction?

Answer 6

Alcohol causes the DNA to precipitate out of solution, making it more visible.