DNA and RNA are two vital biomolecules of the living systems. Both of these nucleic acids account for gene expression and regulation inside the cells.  They are closely associated and depend on each other for carrying out their functions. Hence, they share more similarities with each other than differences.

Some key differences between DNA and RNA.









































































































































































Deoxyribonucleic Acid

Ribonucleic Acid



Strands

  • DNA is mostly double-stranded, helical in shape, and antiparallel strands encircling each other.
  • RNA is mostly single-stranded, and sometimes folded to form double strands.

Sugar Base

  • The DNA molecule contains 5-Carbon deoxyribose sugar as the sugar backbone. It has one oxygen less than ribose sugar.
  • RNA Molecule contains ribose sugar as sugar backbone. 

Nitrogenous base

  • DNA molecule has Adenine, Guanine (Purines), Thymine, and Cytosine (Pyrimidines).
  • RNA molecule contains Adenine and Thymine (Purines) and Cytosine and Uracil (Pyrimidines).

Replication

  • DNA is self-replicating. It makes a copy of itself inside the cell using cellular machinery.

  • RNA is formed by the transcription of DNA.

Location

  • DNA is found in the nucleus of the cell. It is also present inside some cell organelles like Mitochondria and Chloroplasts of eukaryotic cells.


  • 5. RNA is mostly located in close association with ribosomes outside the nucleus and in the cytoplasm.

Length

  • DNA is a relatively long and large molecule with several thousand to billions of nucleotides. A rare Japanese flower named Paris japonica sports an astonishing 149 billion base pairs.


  • RNA is relatively shorter and smaller in size. The size of RNA ranges from (25000 base pairs to 2 million base pairs).

Function

  • DNA functions to transfer genetic information in cellular organisms. DNA also transcribes into mRNA for protein synthesis.


  • RNA acts as a genetic material only for some viruses. Protein is synthesized out of mRNA.

Types

  • DNA based on its structure is classified into five types. A-DNA, B-DNA, C-DNA, D-DNA ,and Z-DNA.

  • The most common types of RNA are tRNA, mRNA, rRNA, and snRNA. Besides there are miRNA, siRNA, lncRNA, and other many other types of RNA which have a role in gene regulation.

UV resistance

  • DNA is susceptible to UV radiations. It changes the geometry and shape of DNA causing mutations and damaging effects.
  • RNA is much more resistant to UV degradation than DNA.

Stability

  • DNA is a highly stable molecule. It is more stable under alkaline conditions. That is because DNA lacks a hydroxyl group on the 2' position in each sugar group.
  • Naturally, RNA is more reactive than DNA. RNA is not stable in alkaline conditions.

Immunogenicity

  • DNA is a weak immunogen with low antigenic activity. Only a few structural genes and certain nucleotide sequences might show an immune response.
  • Most RNAs are immunogenic. They readily elicit an immune response.

Packing

  • DNA is packed into Chromatin by coiling with histone proteins and nucleoproteins. The 23 pairs of chromosomes are DNA packed together.
  •  RNA is in close association with ribosomes. They do not undergo supercoiling with nucleoproteins. 

Quantity of DNA

  • A quantity of DNA inside a cell is fixed. Cells might contain DNA as genomic DNA, Plasmids, or inside cell organelles.
  • The quantity of RNA inside the cell might vary depending on its physiological state. 

Half life

  • The latest estimations show the half-life of DNA is approx. 521 years
  • The half-life of mRNA depends on RNA type. However, it is assumed that mRNA has a half-life of about 10 hours, tRNA up to 80 hours, and tRNA up to 7.8 days.

Detection

  • DNA is analyzed by Southern Blotting.
  • RNA is analyzed with Western Blotting.

Inheritance

  • During cell division, DNA is replicated and inherited into the daughter cells.
  • RNA does not inherit. However, it is transcribed in the daughter cells after cell division. 

Staining with Cationic Dyes

  • DNA stains Blue/ Green with methyl green. It has a high affinity with phosphate radicals in the DNA helix.
  • RNA stains red with Pyronin Y. This dye does not have an affinity for phosphate radicals but intercalates between negatively charged RNA molecules. 

Catalytic activity

  • DNA does not possess catalytic activity.
  • Some exceptional RNAs carry out catalytic activity. It is present in various small ribozymes, the catalytic center of ribosome and spliceosome, and even on some self-splicing group I and II introns. 

Chargaff's Rule

  • DNA follows Chargaff's rule. This rule states DNA from any species of any organism should have a 1:1 stoichiometric ratio of purine and pyrimidine bases.
  • RNA doesn't follow Chargaff's rule. It appears practically impossible for them because they are single-stranded.

Grooves

  • The folds of DNA helix have smaller grooves. This saves the DNA from most enzymatic attacks.
  • RNA has larger grooves and thus is more vulnerable to hydrolytic enzyme attacks.

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