Bioinformatics programmes and genetic engineering techniques have become powerful tools to understand structure-function relationships of macromolecules. This monograph deals with the analyses of proteins and nucleic acids using these tools. The first paper describes development of a new software to analyze the untranslated regions in eukaryotic mRNAs. UTRScan utility has been used to analyze these regions (cis acting elements) in mRNAs. However, the UTRScan is not very sensitive and also not highly specific. We have developed a new algorithm and an Internet based web application tool named UlTRaSCAN, which overcomes these limitations and proved to be highly specific and sensitive in detecting patterns in UTRs. The second paper describes an anomaly observed in the commonly used multiple sequence analysis programmes viz., ClustalW and T-COFFEE. The third and fourth papers combine the knowledge of biochemical and genetic engineering data with bioinformatics data to analyze active sites of enzymes such as polygalacturonases, invertases and fructofuranosyl transferases. I do hope these articles will make an interesting reading not only for the specialists but also for the beginners.