DNA vs RNA

	DNA	RNA
Stands for:	Deoxyribonucleic acid	Ribonucleic acid
Definition:	A nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms	A nucleic acid polymer that plays an important role in the process that translates genetic information from deoxyribonucleic acid(DNA) into protein products
Job/Role:	Medium of long-term storage and transmission of genetic information	Acts as a messenger between DNA and the protein synthesis complexes known as ribosomes
Bases & Sugars:	DNA is a long polymer with a deoxyribose and phosphate backbone and four different bases: adenine, guanine, cytosine and thymine	RNA is a polymer with a ribose and phosphate backbone and four different bases: adenine, guanine, cytosine, and uracil
Types:	Single	1) mRNA (carries DNA message to cytoplasm) 2)tRNA (carries amino acids to mRNA and Ribosomes) 3)rRNA(Ribosomal RNA, workbench for protein synthesis)
Predominant Structure:	Typically a double- stranded molecule with a long chain of nucleotides	A single-stranded molecule in most of it's biological roles and has a shorter chain of nucleotides
Difference:	1.Found in nucleus 2.the genetic material 3. sugar is dexyribose 4. Bases are A,T,C,G	1.Found in nucleus and cytoplasm
Pairing of Bases:	A-T(Adenine-Thymine), G-C(Guanine-Cytosine)	A-U(Adenine-Uracil), G-C(Guanine-Cytosine)
Stability:	Deoxyribose sugar in DNA is less reactive because of C-H bonds. Stable in alkaline conditions. DNA has smaller grooves where the damaging enzyme can attach which makes it harder for the enzyme to attack DNA	Ribose sugar is more reactive because of C-OH (hydroxyl) bonds. Not stable in alkaline conditions. RNA on the other hand has larger grooves which makes it easier to be attacked by enzymes
Unique Features:	The helix geometry of DNA is of B-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 A-Form. RNA strands are continually made, broken down and reused. RNA is more resistant to damage by Ultra-violet rays

The main difference between DNA and RNA is the sugar present in the molecules. While the sugar present in a RNA molecule is ribose, the sugar present in a molecule of DNA is deoxyribose. Deoxyribose is the same as ribose, except that the former has one more OH.

DNA does not usually exist as a single molecule, but instead as a tightly-associated pair of molecules. These two long strands entwine like vines, in the shape of a double helix. This arrangement of DNA strands is called antiparallel. The asymmetric ends of DNA strands are referred to as the 5′ (five prime) and 3′ (three prime) ends. One of the major differences between DNA and RNA is the sugar, with 2-deoxyribose being replaced by the alternative pentose sugar ribose in RNA. The four bases found in DNA are adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T). A fifth pyrimidine base, called uracil (U), usually takes the place of thymine in RNA and differs from thymine by lacking a methyl group on its ring.

Chemical differences between DNA & RNA

Both RNA and DNA are composed of repeated units. The repeating units of RNA are ribonucleotide monophosphates and of DNA are 2'-deoxyribonucleotide monophosphates.

Both RNA and DNA form long, unbranched polynucleotide chains in which different purine or pyrimidine bases are joined by N-glycosidic bonds to a repeating sugar-phosphate backbone.

The chains have a polarity. The sequence of a nucleic acid is customarily read from 5' to 3'. For example the sequence of the RNA molecule is AUGC and of the DNA molecule is ATGC

The base sequence carries the information, i.e. the sequence ATGC has different information that AGCT even though the same bases are involved.

Consequences of RNA/DNA chemistry

The DNA backbone is more stable, especially to alkaline conditions. The 2' OH on the RNA forms 2'3'phosphodiester intermediates under basic conditions which breaks down to a mix of 2' and 3' nucleoside monophosphates. Therefore, the RNA polynucleotide is unstable.

The 2' deoxyribose allows the sugar to assume a lower energy conformation in the backbone. This helps to increase the stability of DNA polynucleotides. The following link shows 3-D models of the DNA and RNA nucleotides.

Cytidine deamination to Uridine can be detected in DNA but not RNA because deamination of Cytidine in DNA leads to Uridine not Thymidine. Uridine bases in DNA are removed by a specific set of DNA repair enzymes and replaced with cytidine bases.