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Question
________is added to precipitate purified DNA.
________is added to precipitate purified DNA.
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Solution
The correct option is B Chilled ethanol
In order to isolate or extract DNA, the cell is lysed. This involves breaking the membranes of the cell to release the DNA and other macromolecules in the medium.
If the cell has a cell wall it has to be treated with the respective degradative enzymes.
In case of plant cells, the cell walls are primarily made of cellulose. This is digested by cellulase treatment.
For a bacterial cell, the cell wall is made up of peptidoglycan which can be degraded by lysozyme treatment.
Fungal cells are protected by a cell wall made up of chitin and chitinase enzymes help in degradation of the cell wall.
Dissolution of the cell wall is followed by the breakdown of the plasma membrane which releases the cell contents in the media.
Though DNA molecules are present in cell lysate, they are wrapped around proteins. So, to separate it, protease treatment is given.
Later on, chilled ethanol is added. Ethanol will interfere with the DNA-water molecule interactions. This will reduce the solubility of DNA in the water. As a result, DNA will precipitate out. A colder temperature will also help in faster precipitation. Therefore, chilled ethanol helps to precipitate the purified DNA.
In order to isolate or extract DNA, the cell is lysed. This involves breaking the membranes of the cell to release the DNA and other macromolecules in the medium.
If the cell has a cell wall it has to be treated with the respective degradative enzymes.
In case of plant cells, the cell walls are primarily made of cellulose. This is digested by cellulase treatment.
For a bacterial cell, the cell wall is made up of peptidoglycan which can be degraded by lysozyme treatment.
Fungal cells are protected by a cell wall made up of chitin and chitinase enzymes help in degradation of the cell wall.
Dissolution of the cell wall is followed by the breakdown of the plasma membrane which releases the cell contents in the media.
Though DNA molecules are present in cell lysate, they are wrapped around proteins. So, to separate it, protease treatment is given.
Later on, chilled ethanol is added. Ethanol will interfere with the DNA-water molecule interactions. This will reduce the solubility of DNA in the water. As a result, DNA will precipitate out. A colder temperature will also help in faster precipitation. Therefore, chilled ethanol helps to precipitate the purified DNA.
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