Alfred Hershey and Martha Chase proved that DNA is the genetic material.
Experiment of Hershey and Chase
1. They made two different preparations of the phage; in one, the DNA was made radioactive with \(^{ 32 }P\) and in the other, the protein coat was made radioactive with \(^{ 35 }{ { S } }\).
2. These two phage preparations were allowed to infect the bacterial cells separately.
Soon after infection, the cultures were gently agitated in a blender to separate the adhering protein coats of the virus from the bacterial cells.
3. The culture was also centrifuged to separate the viral coat and the bacterial cells.
4. It was found that when the phage containing radioactive DNA was used to infect the bacteria, its radioactivity was found in the bacterial cells (in the sediment) indicating that the DNA has been injected into the bacterial cell.
5. So, DNA is the genetic material and not proteins.

Alfred Hershey and Martha Chase proved that DNA is the genetic material.
Experiment of Hershey and Chase
1. They made two different preparations of the phage; in one, the DNA was made radioactive with \(^{ 32 }P\) and in the other, the protein coat was made radioactive with \(^{ 35 }{ { S } }\).
2. These two phage preparations were allowed to infect the bacterial cells separately.
3.Soon after infection, the cultures were gently agitated in a blender to separate the adhering protein coats of the virus from the bacterial cells.
4.  The culture was also centrifuged to separate the viral coat and the bacterial cells.
5.  It was found that when the phage containing radioactive DNA was used to infect the bacteria, its radioactivity was found in the bacterial cells (in the sediment) indicating that the DNA has been injected into the bacterial cell.
6. So, DNA is the genetic material and not proteins.

During RNA processing
(i)unwanted nucleotides are removed
(ii)useful regions are rejoined
(iii)certain nucleotides are added
(iv)some nucleotides are modified, and
(v)folding of molecule

Auxotroph,because it needed increase nutrision(G.auxano=to increase),it needed citrulline as it lacked the gene for the enzyme that could catalyse the chage of orithine into citrulline.

DNA expresses its genetic information by transcribing mRNA and synthesising proteins