How Bacteria Reproduce

1. How Bacteria Reproduce By: Stephanie and Anna

2. 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

3. 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.

4. 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

5. 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

6. Continuation… • Scientists use this as a tool for genetic engineering to introduce new genes into cells

7. 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 canlive in extreme conditions

8. Continuation… • Endospores lose their coat and grow and divide like normal cells when favourable conditions return • Endospores can be killed

9. 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

10. Continuation… • Food must be heated under high pressure (with the temperature above the boiling point of water) to ensure the bacterial endospores are killed