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Prokaryotic World

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

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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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