DNA Extraction

DNA Extraction:

Scientists isolate DNA for:

1. Genetic testing

2. Body identification

3. Analysis of forensic evidence

DNA extraction is important because the DNA first needs to be purified away from proteins and other contaminants.

Steps:

1. Collect cells from test subject

2. Burst cells open to release DNA

3. Separate DNA from proteins and debris

4. Isolate concentrated DNA

2. Burst cells open to release DNA

Lysis solution:

Contains -

Detergent

The detergent disrupts the cell membrane and nuclear envelope, causing the cells to burst open and release their DNA.

Enzyme called proteinase K

The DNA is still wrapped very tightly around proteins called histones, and the proteinase K cuts apart the histones to free the DNA.

3. Separate DNA from proteins and debris

Salt solution:

Salt causes proteins and cellular debris to clump together.

Centrifuge:

- When placing the tube containing the DNA into the centrifuge, a tube containing water is placed opposite the tube in order to ‘balance’ it.

- Inside the centrifuge, the tubes are spun around at high speed, which causes the heavy clumps of protein and debris to sink to the bottom, while the strands of DNA remain distributed throughout the liquid. The DNA can then be separated from the proteins and debris.

4. Isolate concentrated DNA

Isopropyl alcohol/ethanol:

DNA is not soluble in isopropyl alcohol and so it comes out of the solution. When put into the centrifuge again, the DNA settles at the bottom of the tube instead.

Notes taken from http://learn.genetics.utah.edu/content/labs/extraction/ when completing the DNA Extraction Virtual Lab Activity :)