The present book has been designed to provide detailed knowledge about molecular biology in relation with crop improvement. The topics mainly covered includes cell structure and function, molecular genetics and gene expression, molecular biology techniques, PCR and gene cloning, mutations and in vitro mutagenesis, molecular markers and genomics, tissue culture and plant genetic engineering, transgenics, biosafety and regulations and biomolecules like carbohydrates, proteins, lipids, nucleic acids and enzymes. Hope this book would be useful for graduate and post-graduate students of Agriculture, Biotechnology and Biology in all the Universities. This will also be useful for those appearing in competitive examinations such as Agricultural Research Services of the Indian Council of Agricultural Research, National Eligibility Test, Civil Services Examinations and other allied examinations.