Extraction of DNA from fruit

Question 1

Explain 1st part of method: (Prepping strawberry before tube)

Answer 1

1. Crush strawberry with 20cm3 DNA extraction buffer. Do with pestle + mortar
2. Strain this into beaker using tea strainer + muslin
3. Add 1cm3 of protease enzyme to filtrate

Question 2

Explain 2nd part of method: (Boiling tubes)

Answer 2

4. Pour filtrate into boiling tubes
5. Add 5cm3 cold ethanol to filtrate
6. Tip boiling tubes to side + slowly roll ethanol down inside wall of boiling tubes- so it forms layer ontop of filtrate
7. Let it stand for 5 mins. Then DNA will form white precipitate where layer of buffer meets ethanol - scoop this with inoculating loop

Question 3

What is the function of the detergent solution?

Answer 3

Disrupts phospholipid bilayer of cell membranes, releasing the DNA

Question 4

Explain the function of the salt:

Answer 4

Neutralises charge between phosphate groups - reduces solubility of DNA in water

Question 5

What is the function of the protease solution?

Answer 5

Protease enzymes digest histone proteins, just leaving the DNA

Question 6

Why does the DNA precipitate into the ethanol?

Answer 6

DNA is insoluble in ethanol so forms a precipitate

Question 7

What is the structure of the extracted DNA?

Answer 7

Its amorphous (without shape), gel like, white, + translucent