Biomolecules in the interstellar medium and in comets

We review recent studies of organic molecule formation in dense molecular clouds and in comets. We summarise the known organic. inventories of molecular clouds and recent comets, particularly Hale-Bopp. The principal chemical formation pathways involving gas phase reactions, as well as formation by catalytic reactions on grain surfaces or through dust fragmentation, are identified for both dense clouds and cometary comae. The processes leading to organic molecules with known biological function, carbon chains, deuterium fractionation, HNC and S-bearing compounds are described. Observational searches for new interstellar organics are outlined and the connection between observed interstellar organics and those detected in comets Hale-Bopp and Hyakutake are discussed. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.