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Course: Class 12 Biology (India) > Unit 10
Lesson 3: Tools and processes of recombinant technologyEnzymes for isolation of DNA
Isolation of genetic material using enzymes and spooling.
This article reviews the names and functions of the various enzymes that can help isolate DNA from a cell.
Key terms
| Term | Meaning |
|---|---|
| lysozyme | enzyme that breaks down peptidoglycans in cell walls of bacteria |
| cellulase | enzyme that breaks down cellulose in cell walls of plants |
| chitinase | enzyme that breaks down chitin in cell walls of fungi |
| protease | enzyme that breaks down proteins |
| ribonuclease | enzyme that breaks down RNA, also called RNase |
| spooling | method used for collecting large amounts of DNA |
How do you get DNA out of a cell?
In order to perform a polymerase chain reaction (PCR) or a restriction enzyme digest, we first need to isolate DNA from the inside of a cell. On top of that, the DNA needs to be purified, so that it's not mixed up with a bunch of other macromolecules.
The following section provides the basic recipe to extract and purify DNA from a sample.
Recipe for DNA
- First, grind up or violently disturb the sample. DNA is usually extracted from a group of cells, or a piece of tissue, and this step removes 'clumps' that stick together.
- Depending on the kind of organism, add the required amount of one the following enzymes - lysozyme (for bacteria), cellulase (for plant cells), or chitinase (for fungus). This ensures that cell membrane or wall is broken.
- Next, add some protease. This enzyme will get rid of any proteins, such as histones, which can be found bound to DNA.
- Remove any RNA present with the help of a ribonuclease.
- Finally, precipitate DNA out using chilled ethanol. Collect the condensed DNA using spooling, or other techniques of your choice.
Refer to the table at the top of this article for a refresher on what each enzyme does.
Note - nowadays, there are readymade kits that can be used to extract DNA. Simply follow the protocol for a quick preparation of fresh nucleic acid!
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