RNA interference (RNAi) is an important pathway that is used in many different organisms to regulate gene expression. This animation introduces the principles of RNAi involving small interfering RNAs (siRNAs) and microRNAs (miRNAs).
Over millions of years, retroviruses, which insert their genetic material into the host genome as part of their replication, have left behind bits of their genetic material in vertebrate genomes.
The ebola virus is one of the nastiest pathogens known to man. It corrodes blood vessels and stops clotting, leaving most of its human victims bleeding to death through their pores. And guinea pigs — along with opossums, wallabies and insect-eating bats — have it in their genes.
Scientists still have not come close to creating a living organism from nonbiological materials, especially ones that might have existed on Earth four billion years ago. In other words, scientists have not shown how life began, how inanimate materials become animate.