The entire DNA content of the cell is what is known as
genome. The segment of genome that is transcribed into RNA is called gene. All organisms
self replicate due to the presence of genetic material DNA, the polynucleotide consisting
of four bases Adenine (A), Thymine (T), Guanine (G) and Cytosine (C)
Adenine
Thymine
Guanine
Cytosine
Figure 1: DNA and its alphabets A, T, G & C the nucleic acid bases.
It suggests that hereditary information is transferred in the form of genes
containing four bases. Understanding about these genes is one of the modern day
challenges. Some of the questions which arises are: Why only five percent of
the entire DNA is in the form of genes?, What is the rest of the DNA responsible
for?, Under what conditions genes are expressed?, Where, when and how to regulate
gene expression? are some unsolved puzzles. The information present in DNA is
expressed via RNA molecules into proteins which are responsible for carrying
out various activities. This information flow is called the central dogma of
molecular biology (Fig.2).
