BIOMOLECULES
DEOXYRIBONUCLEICACID
Nucleic acids are the organic materials present in all organisms in the form of DNA or RNA. These
nucleic acids are formed by the combination of nitrogenous bases, sugar molecules and phosphate
groups that are linked by different bonds in a series of sequences. The DNA structure defines the
basic genetic makeup of our body. In fact, it defines the genetic makeup of nearly all life on e
DNA
“DNA is a group of molecules that is responsible for carrying and transmitting the hereditary
materials or the genetic instructions from parents to offsprings.”
This is also true for viruses as, as most of these entities have either RNA or DNAt their genetic
material. For instance, some viruses may have RNA as their genetic material, while others have
DNA as the genetic material. The Human Immunodeficiency Virus (HIV) contains RNA, which
is then converted into DNA after attaching itself to the host cell.
Apart from being responsible for the inheritance of genetic information in all living beings, DNA
also plays a crucial role in the production of proteins. Nuclear DNA is the DNA contained within
the nucleus of every cell in a eukaryotic organism. It codes for the majority of the organism’s
genomes while the mitochondrial DNA and plastid DNA handles the rest.
The DNA present in the mitochondria of the cell is termed mitochondrial DNA. It is inherited from
the mother to the child. In humans, there are approximately 16,000 base pairs of mitochondrial
DNA. Similarly, plastids have their own DNA, and they play an essential role in photosynthesis.
DNA Types
There are three different DNA types:
A-DNA: It is a right-handed double helix similar to the B-DNA form. Dehydrated DNA takes an A
form that protects the DNA during extreme conditions such as desiccation. Protein binding also
removes the solvent from DNA, and the DNA takes an A form.
B-DNA: This is the most common DNA conformation and is a right-handed helix. The majority of
DNA has a B type conformation under normal physiological conditions.
Z-DNA: Z-DNA is a left-handed DNA where the double helix winds to the left in a zig-zag pattern. It
was discovered by Andres Wang and Alexander Rich. It is found ahead of the start site of a gene and
hence, is believed to play some role in gene regulation.
