GENOMICS AND PROTEOMICS
Every organism possesses a genome that contains the biological information needed to
construct and maintain a living example of that organism. Most genomes, including the
human genome and those of all other cellular life forms, are made of DNA
(deoxyribonucleic acid), but a few viruses have RNA (ribonucleic acid) genomes. DNA
and RNA are polymeric molecules made up of chains of monomeric subunits called
nucleotides. Each molecule of DNA comprises two polynucleotides wound around one
another to form the famous double helix, in which the two strands are held together by
chemical bonds that link adjacent nucleotides into structures called base pairs.
The human genome, which is typical of the genomes of all multicellular animals, consists
of two distinct parts
• The nuclear genome comprises approximately 3,235,000,000 base pairs of DNAs,
divided into 24 linear molecules, the shortest 48,000,000 base pairs in length and
the longest 250,000,000 base pairs, each contained in a different chromosome.
These 24 chromosomes consist of 22 autosomes and the two sex chromosomes,
X and Y. Altogether, some 45,500 genes are present in the human nuclear genome.
• The mitochondrial genome is a circular DNA molecule of 16,569 base pairs, up
to 10 copies of which are present in each of the energy-generating organelles
called mitochondria. The human mitochondrial genome contains just 37 genes.
Introduction:
The genome is a store of biological information, but on its own it is unable to release that
information to the cell. Utilization of the biological information contained in the genome
requires the coordinated activity of enzymes and other proteins, which participate in a
complex series of biochemical reactions referred to as genome expression. The initial
product of genome expression is the transcriptome, a collection of RNA molecules
derived from those genes that are active in the cell at a particular time. The transcriptome
is maintained by the process called transcription, in which individual genes are copied
into RNA molecules. The second product of genome expression is the proteome, the cell’s
repertoire of proteins, which specifies the nature of the biochemical reactions that the
cell can carry out. The proteins that make up the proteome are synthesized by
translation of some of the individual RNA molecules present in the transcriptome.
