Modern Genetics

Genetics deals with various concepts and phenomena related to inheritance. Mendel's findings sowed the seeds for understanding the secrets of heredity and paved the way for further knowledge on genes and chromosomes. The post mendelian period was remarkable in that many concepts and hypotheses related to general genetics such as factor(gene) interactions, sex determination, linkage, sex linkage, crossing over, cytoplasmic inheritance, multiple allelism, polygenic inheritance were added. The discovery of double helical DNA by Watson and Crick in 1952 has unraveled the secrets of gene functions. The voluminous works on Drosophila and prokaryotes like Escherichia coli opened up a new era of molecular or modern genetics.

In modern genetics, human genetics constitutes a part. It attempts to bring informations most important for understanding the genetics of man who is also a species like any other taxonomic species. Human genetics involves the identification of human chromosomes, genetics engineering prospects, genetic diseases and gene therapy, cloning devices, transgenic or genetically modified organisms etc. Towards this line, the modern genetics also deals wih the human genome project, bioinformatics, and proteomics.

Karyotyping:

This is a technique through which the complete set of chromosomes are separated from a cell and the chromosomes are lined up in a karyogram. The term karyogram is replaced by another word called ideogram, which is a diagrammatic representation of chromosomes.

Uses:

• It helps to identify the sex of individuals.
• Genetic diseases in human beings can be detected by this .
• The chromosomal abnormalities could be detected.

Genetic Engineering: (Recombinant DNA technology): It deals with the manipulation of genes according to human will. A gene of known function can be transferred from its normal location into an entirely different cell or organism, through a suitable carrier or vector. The carrier may be a plasmid DNA segment of a bacterium. The gene transferred likewise start functioning to synthesize a particular protein in the new environment. Thus the gene can function irrespective of its environment formed the basis of genetic engineering.

Plasmids:

It is a circular DNA with about 200 -300 nucleotides. It is present in bacterial cells alongside their main chromosomes.