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Prokaryotic World

Explore the structural features and reproductive methods of prokaryotic cells, particularly bacteria, including motility, ecological roles, and the fascinating Cyanobacteria. Delve into the world of E. coli and discover its unique characteristics.

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Prokaryotic World

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  1. Prokaryotic World

  2. Eukaryotic: cells have a nucleus Prokaryotic: cells have no nucleus Bacteria Archaea Eukarya The Three Domains Kingdoms: Animalia Plantae Fungi Protista Bacteria Cyanobacteria “Extremophiles”

  3. Prokaryotic cells

  4. Bacterial structure • Bacteria have no nucleus, but do have: • a cell membrane • a cell wall • a capsule • flagellae or cillia

  5. Bacterial Structure • Bacteria come in three common shapes: • Coccus (spherical) • Bacillus (rod-shaped) • Spirillus (spiral-shaped)

  6. Motility • Some bacteria are motile and can move by means of a flagella. • A simple “wheel and axle” arrangement of proteins forms the base of the flagellum.

  7. Reproduction • Bacteria reproduce by binary fission (simple cell division). • However, they can also exchange genetic information by trading plasmids (DNA rings) across conjugation bridges.

  8. Ecological roles • Bacteria play a wide range of roles in the ecology. • Many are decay organisms, breaking down dead material and releasing inorganic compounds such as nitrogen compounds or carbon dioxide. • Some are symbiotic organisms that live in animal digestive systems. • Some are disease-causing organisms.

  9. Ecological Roles • Nitrogen-fixing bacteria are associated the the roots of certain plants. These bacteria convert nitrogen gas into compounds that plants can absorb.

  10. Escherischia coli • E. coli is a well-known gut bacteria. • Like all prokaryotes, it has no nucleus and no membrane-bound organelles, but is highly adaptable.

  11. E. coli • The “hot dog” shape is a typical “bacillius” form. • Normally, E. coli is a part of our intestinal flora. Out of place, however, it can cause serious infections.

  12. E. coli • In this photo, you can see the bacterial DNA coiled up in the center of the organism. • Bacterial DNA forms one long loop rather than strands. • Small loops (“plasmids”) can be shared between bacteria.

  13. Cyanobacteria • These are photsynthetic bacteria that gather in long strands. • Cyanobacteria were probably the first photosynthetic organisms on the planet.

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