Compare the structure and characteristics of DNA & RNA and prove that DNA is better nucleic acid for inheritance. Please send solution quickly and point wise (4M)

Dear Sayyidh,

 A) The following distinguishing characteristics can be used to differentiate between DNA and RNA: 

• Pentose sugar - the deoxyribose of DNA has one less oxygen than the ribose of RNA 
   
• Nitrogenous bases - DNA contain adenine, thymine, cytosine, guanine; RNA contains adenine, uracil, cytosine, and guanine. 
   
• Strandedness - DNA is double-stranded and RNA is single-stranded. 
   
• Functions - DNA stores genetic information and RNA transfers the information to other places in the cell. 
   
• Location - DNA is only found in the nucleus whereas RNA can be found in both the nucleus and cytoplasm. DNA contains the information for protein synthesis; RNA carries out protein synthesis. 
   
• Reactivity - DNA is less reactive due to stable C-H bonds; RNA is more reactive due to C-OH bond. DNA is stable in alkaline/basic conditions while RNA is unstable in alkaline/basic conditions. 
   
• UV radiation - DNA is more easily damaged. 
   
• Grooves - DNA has smaller grooves reduce enzyme ability to attach and damage while RNA has large grooves enable enzymes to attach and damage. 
   
• Geometry - DNA has B-form helix geometry and RNA has A-form helix geometry

B) 

Hershey and Chase Experiment to Confirm DNA as the Genetic Material

• Hershey and Chase worked on bacteriophages (viruses that infect bacteria).
• When a bacteriophage infects a bacterium, the viral genetic material gets attached with the bacterial genetic material and bacteria then treats the viral genetic material as its own to synthesise more viral particles.
• Hershey and Chase worked to discover whether it was a protein or DNA that entered the bacteria from virus.
• They labelled some phages with radioactive sulphur and the others with radioactive phosphorus.
• These radioactive phages were used to infect E. coli.
• E.coli was then blended and centrifuged to remove viral particles.
• It was observed that bacteria with radioactive DNA were radioactive while those with radioactive proteins lost their radioactivity.
• This showed that it is the DNA that enters the bacteria from viruses and not proteins. Hence, it was concluded that DNA is the genetic material.
  

In this experiment, sulphur (absent in DNA) in the proteins was labelled and phosphorus (absent in proteins) of DNA was labelled. Since the radioactivity was seen in the cells in which phosphorus of the phage DNA was labelled and not in labelled sulphur of proteins.


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