Structural Biochemistry/Nucleic Acid/Difference between DNA and RNA

DNA and RNA are different from their structure, functions, and stabilities. DNA has four nitrogen bases adenine, thymine, cytosine, and guanine and for RNA instead of thymine, it has uracil. Also, DNA is double-stranded and RNA is single-stranded which is why RNA can leave the nucleus and DNA can't. Another thing is that DNA is missing an oxygen.

Predominant structures
DNA is a double-stranded molecule with a long chain of nucleotides while RNA is only single-stranded. In most of its biological roles and has a shorter chain of nucleotides (after transcription and splicing, only exons remain in RNA). DNA exists mainly in a double helix form while RNA will take on many different shapes and sizes such as the 'hair pin formation'. DNA is used to carry an organism's genetic information while RNA takes on many different roles, for instance, RNA can act as an enzyme such as ribozyme. There is one single type of DNA while there are many types of RNA that have different functions such as mRNA (carries DNA message to cytoplasm), tRNA (carries amino acids to mRNA and Ribosomes), rRNA (Ribosomal RNA, workbench for protein synthesis). DNA cannot catalyze its own synthesis while RNA can. This supports the RNA World Hypothesis. The pairing of bases in DNA including A-T(Adenine-Thymine) and G-C(Guanine-Cytosine)is different to that of RNA including A-U(Adenine-Uracil) and G-C(Guanine-Cytosine).

Bases and sugars
DNA is a long polymer with deoxyriboses and a phosphate backbone. Having four different nitrogenous bases: adenine, guanine, cytosine and thymine. RNA is a polymer with a ribose and phosphate backbone. Four different nitrogenous bases: adenine, guanine, cytosine, and uracil.

Structure of ribose in RNA

Functions
DNA is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. It is a medium of long-term storage and transmission of genetic information, while RNA is a nucleic acid polymer that plays an important role in the process of translating genetic information from deoxyribonucleic acid (DNA) into protein products. RNA acts as a messenger between DNA and the protein synthesis complexes known as ribosomes.

Both DNA and RNA start synthesis in the 5'-3' direction. However, no primer is needed for RNA. In addition, only RNA polymerase lacks the ability to detect errors of base pairing.

Stabilities
Deoxyribose sugar in DNA is less reactive because of C-H bonds on the second carbon (C2). DNA is stable in alkaline conditions. It has smaller grooves where the damaging enzyme can attach which makes it harder for the enzyme to attack DNA; RNA, on the other hand, has larger grooves which makes it easier to be attacked by enzymes. RNA, ribose sugar is more reactive because of the presence of hydroxyl group on C2. RNA is not stable in alkaline conditions because bases can easily deprotonate the Hydrogen from the -OH on C2. After deprotonation, the negatively charged oxygen may attack the Phosphate at the PO4, kicking off the Oxygen connected to the 5'C of next nucleotide over, resulting in hydrogenation.

Unique features
The helix geometry of DNA is of β-Form. DNA is completely protected by the body i.e. the body destroys enzymes that cleave DNA. DNA can be damaged by exposure to ultra-violet rays. The helix geometry of RNA is of α-Form. RNA strands are continually made, broken down and reused. RNA is more resistant to damage by ultra-violet rays.

Comparison chart
Here is a chart that shows the differences between DNA and RNA: