Genetic information is carried in the linear sequence of nucleotides in DNA. Its expression involves the translation of the linear sequence of specific regions of DNA existing in the nucleus of the cell (called coding regions or genes) into a collinear sequence of amino acides (proteins). As an intermediate step, however, DNA must be copied into different types of polynucleotide known as the ribonucleic acid (RNA) which retains all the information of the DNA sequence from which it was copied. Single-stranded RNA molecules are synthesized by a process known as DNA transcription which is regulated by interactions between DNA sequences located upstream of the gene (promoters) and proteins (transcription factors). Thousands of RNA transcripts can be made from the same DNA segment in a given cell. Many of these RNA molecules undergo major chemical changes before they leave the nucleus to serve as the messenger RNA (mRNA) molecules that direct the synthesis of proteins in the cytosol. Fragments of DNA can be amplified by a process called DNA cloning which consists in inserting the DNA into a plasmid or a bacterial virus and then growing these in bacterial (or yeast) cells.
ABOUT THE AUTHOR S.P. Singh
Dr. S.P. Singh, obtained degrees of B.Sc. (Hons.) Ag. & A.H. and M.Sc. (Ag.) Horticulture from G.B. Pant University of Agriculture & Technology, Pantnagar (UP) India in 1964 and 1970 respectively. In the same University, he conducted research and imparted technical know-how on seed production technology in cereal and vegetable crops to the progressive farmers of Tarai region of western U.P. He was awarded Senior Research Fellowship by CSIR, New Delhi leading to Ph.D. degree in Horticulture at National Botanical Reserch Institute, Lucknow under Kanpur University, Kanpur (UP) in 1974-78. He joined Konkar Krishi Vidyapeeth, Dapoli, Ditt. Ratnagiri (MS) as Assistant Professor in 1978 and worked in the cadre of Associate Professor from January 1979 to Nov. 1983 in the same University. Presently Dr. Singh is serving as Associate Professor of Horticulture at Gujarat Agricultural University, Junagadh Campups, Junagadh since December, 1983. Dr. Singh has published more than 50 research papers and 65 semi-research articles in Horticulture. Dr. Singh is a life member of the Indian Journal of Plant Science Research and Indian Farmers’ Digest His main areas of interests are floriculture, olericulture and plantation crops. He is author of three more books, viz. 1. Mist propagation, 2. The Gliricidia, 3. Scientific Management of Arecanut Gardens.
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