Structure of DNA and RNA
DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid) are fundamental nucleic
acids that serve as the genetic material in all known living organisms and many
viruses. They are both long-chain polymers composed of repeating units called
nucleotides. Each nucleotide is made up of three components: a nitrogenous base, a
five-carbon sugar (pentose), and a phosphate group.
Pentose Sugars
The main structural difference between DNA and RNA lies in their sugar
components:
DNA contains deoxyribose, a five-carbon sugar in which the 2′ carbon atom
lacks a hydroxyl (-OH) group. Instead, it has a hydrogen atom, which
contributes to the overall stability and resistance to hydrolysis, making DNA a
better long-term storage molecule for genetic information.
RNA contains ribose, which has a hydroxyl (-OH) group at the 2′ carbon. This
hydroxyl group makes RNA chemically more reactive and less stable than
DNA. However, it also allows RNA to adopt a variety of structural
conformations and perform multiple roles in the cell, such as acting as a
messenger (mRNA), a structural and catalytic component (rRNA), or an
adaptor molecule (tRNA).
The presence or absence of the hydroxyl group significantly influences the biological
function and stability of the molecules. Due to the lack of OH group at 2’ Carbon the
DNA’s gains chemical stability which makes it suitable for preserving genetic
information, while RNA’s flexibility and reactivity make it ideal for short-term
processes like protein synthesis, gene regulation, and catalysis (in the case of
ribozymes).
Other Key Differences to Structure:
Lifespan: DNA molecules are long-lived, often persisting for the entire
lifespan of a cell or organism. In contrast, RNA molecules are generally short-
lived and are rapidly degraded after their function is fulfilled.
Function: DNA’s primary role is to store and transmit genetic information.
RNA performs various roles including carrying genetic messages (mRNA),
forming core structural and enzymatic components of ribosomes (rRNA), and
aiding in protein synthesis (tRNA), among others.
Base Composition: DNA contains the bases adenine (A), guanine (G),
cytosine (C), and thymine (T), while RNA contains uracil (U) in place of
thymine.
Phosphodiester Bond
Nucleotides are linked together to form long chains (polynucleotides)
through/phosphodiester bonds. The bond is formed between the 3' carbon atom of
