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How Bacteria Reproduce By: Stephanie and Anna Asexual Reproduction Bacterial cells cannot reproduce Lack nuclei therefore cannot go through mitosis or meiosis Genetic material is contained in a single chromosome with the cell Binary fission: the asexually reproductive process of cell division in bacteria As a bacterial cell grows, it duplicates its original, single chromosome Continuation… It gets longer and separates into two chromosomes. Builds a wall and than splits itself into two smaller cells. The two smaller cells are genetically identical This is sequence is called exponential growth. This process happens all very quickly , reproducing two new cells every 20 minutes. Sexual Reproduction Conjugation: produces cells with new genetic combinations Some may be better adapted to changing conditions Bacterial cells become linked through pili (singular pilus) Bacterium transfers all or part of its chromosome to the other The receiving cell undergoes binary fission to produce more cells with the same genetic make-up Gene Transfer Plasmids: small loops of DNA that separate from the main chromosome Contain from one to a few genes which are different than the ones found in the chromosome Can split from the chromosome and rejoin it Important method of producing genetic recombination Plasmids are transferred during conjugation Continuation… Scientists use this as a tool for genetic engineering to introduce new genes into cells Spore Formation Life cycle includes a dormant stage Cells can survive in an unfavourable environment Develop a tough outer coating around their DNA Forms small seed like structures called endospores Bacteria do not grow or reproduce in the endospore stage Endospores can live in extreme conditions Continuation… Endospores lose their coat and grow and divide like normal cells when favourable conditions return Endospores can be killed Bacteria and Human Health Anaerobic: reactions in the absence of molecular oxygen Botulism: food poisoning caused by anaerobic bacteria Bacteria forms endospores that germinate in anaerobic conditions Bacteria’s metabolism produces toxic products that cause illness or death in humans Bacteria are not dangerous unless they’re trapped in anaerobic conditions for a long period of time Continuation… Food must be heated under high pressure (with the temperature above the boiling point of water) to ensure the bacterial endospores are killed