An Overview of Genomics :
Process of life of an organism is defined, driven and depictedby its genetic constitution, or the genome. A genome is a collection genetic material present in the cell as nuclear or organelle DNA. To be precise, it is the sum of alL single copy genetic materials present in the cellular subcompartments. Thus a diploid organism
having two copies of each chromosome contains genetic material constituting two copies of the genome, while a gamete of the same organism contains single copy of the same. Organelle genome is shared by chioroplast and mitochondria. In these two organelle genetic material is present in single copy per organelle, although many copies of organelle ensures that a cell harbours many copies of mitochondrial or plastid genome. Unraveling the structure and function of the genome is, therefore, the central objective of biological science. Technologies that would help to understand the basis of genetic, biochemical and physiological processes are pivotal to execute the knowledge for the betterment of mankind and environment.
The foundation of the principles of behaviour and perpetuation of an organism’s phenotypic expression was laid by an Austrian monk Gregor Johan Mendel, who in 1865 showedthat the pattern of inheritance and expression of a pheriotypic character can be explained by simple probabilistic rules. This led
to development of a new biological science called ‘genetics’, the study of heredity and variation. The determinants of the phenotypic expressions were termed as ‘ekrnt-nls’ by Mcndel, which later became famous as ‘gene’, a term coined by Johansscn In 19. In essence. Mendel’s laws showed that the phenotypic
characters are governed by genes, which are present in alternate forms called alleles, During gamete formation these alleles segregate, unite in progeny through fertilization and rcsgregate during gamete formation in the progeny.Oneof the alternate forms or alleles remains silent or recessive inheterozygous condition, but is not lost in the first filial gcneration It reappears in the secondfillal generation as a recessive trait with two copies of the recessive allele in the zygote. Moreover, segregation behaviour of one set
of alleles of a gene is independent of segregation behaviour of another set of alleles of another gene. The clarornowmal Sfwory of &writance, proposed by Sutton and Bovei-v predicted that these genes are present on chromosomes, which constitutes the genorne of eukaryotic organisms However, how such simple rules explain the complexity of life was an intriguing question. It soon became clear that although the basic underlying principle remains the same, the structure and pattern of gene expression is extremely complex and variable. A phenotypic expression may be controlled by a single gene few genes or many genes. Some of the genes may interact with each other and with environment to create variation in the population, while some gets permanently altered naturally or under environmental influences. The genes can be mapped on particular positions on chromosomes or the genomne through various genetic and physical mapping techniques. A gene
wp is therefore is a linear array of genes on chromosomes or genetic material maintaining a specific dltance from each other either In terms of recombination frequency or actual physical distance. Fine
structure of the genes was determined in the 1950s showing genes are further suf’dwrsrfrk in smaller functional compartments. During these periods it was established that the genes arc made of linear
combination of nucleotides having a functional expression, the
Process of life of an organism is defined, driven and depictedby its genetic constitution, or the genome. A genome is a collection genetic material present in the cell as nuclear or organelle DNA. To be precise, it is the sum of alL single copy genetic materials present in the cellular subcompartments. Thus a diploid organism
The foundation of the principles of behaviour and perpetuation of an organism’s phenotypic expression was laid by an Austrian monk Gregor Johan Mendel, who in 1865 showedthat the pattern of inheritance and expression of a pheriotypic character can be explained by simple probabilistic rules. This led
to development of a new biological science called ‘genetics’, the study of heredity and variation. The determinants of the phenotypic expressions were termed as ‘ekrnt-nls’ by Mcndel, which later became famous as ‘gene’, a term coined by Johansscn In 19. In essence. Mendel’s laws showed that the phenotypic
characters are governed by genes, which are present in alternate forms called alleles, During gamete formation these alleles segregate, unite in progeny through fertilization and rcsgregate during gamete formation in the progeny.Oneof the alternate forms or alleles remains silent or recessive inheterozygous condition, but is not lost in the first filial gcneration It reappears in the secondfillal generation as a recessive trait with two copies of the recessive allele in the zygote. Moreover, segregation behaviour of one set
of alleles of a gene is independent of segregation behaviour of another set of alleles of another gene. The clarornowmal Sfwory of &writance, proposed by Sutton and Bovei-v predicted that these genes are present on chromosomes, which constitutes the genorne of eukaryotic organisms However, how such simple rules explain the complexity of life was an intriguing question. It soon became clear that although the basic underlying principle remains the same, the structure and pattern of gene expression is extremely complex and variable. A phenotypic expression may be controlled by a single gene few genes or many genes. Some of the genes may interact with each other and with environment to create variation in the population, while some gets permanently altered naturally or under environmental influences. The genes can be mapped on particular positions on chromosomes or the genomne through various genetic and physical mapping techniques. A gene
wp is therefore is a linear array of genes on chromosomes or genetic material maintaining a specific dltance from each other either In terms of recombination frequency or actual physical distance. Fine
structure of the genes was determined in the 1950s showing genes are further suf’dwrsrfrk in smaller functional compartments. During these periods it was established that the genes arc made of linear
combination of nucleotides having a functional expression, the
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