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Bacterial conjugation, computer artwork. Conjugation is the process by which genetic material is transferred from one bacterium to another. Here a pilus (hair-like structure) connects the donor bacterium to the recipient cell. A circular molecule of DNA (deoxyribonucleic acid, known as a plasmid (not seen), passes through the pilus and will be incorporated into the recipient bacterium's genome. Plasmids often carry genes that confer advantages, such as antibiotic resistance or the ability to use a new metabolite. (KEYSTONE/SCIENCE PHOTO LIBRARY/DAVID MACK)