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2.1 The Prokaryotes: Eubacteria and Archaea

2.1 The Prokaryotes: Eubacteria and Archaea. Grade 11 University Biology. Chart comparing prokaryotes and eukaryotes. Importance of prokaryotes. Disease-causing bacteria (called pathogens ) are responsible for many human diseases such as cholera and leprosy

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2.1 The Prokaryotes: Eubacteria and Archaea

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  1. 2.1 The Prokaryotes: Eubacteria and Archaea Grade 11 University Biology

  2. Chart comparing prokaryotes and eukaryotes

  3. Importance of prokaryotes • Disease-causing bacteria (called pathogens) are responsible for many human diseases such as cholera and leprosy • Ecological role: many are decomposers or producers • Live in animals’ intestine and aid in digestion (in humans, they produce vitamin K and B12) • Commercial uses: production of cheese, yogourt, soy sauce, chocolate and antibiotics

  4. Domain Eubacteria • Have lived on Earth for more than 3.5 billion years • There are 6 important groups. See Table 1 on p. 48 for key features.

  5. Characteristics of all bacteria: Structure • Contain 1 chromosome in form of loop in area called nucleoid (some bacteria also have one or more small loops of DNA called plasmids ) • Have one or more flagella for movement and small hair-like structures called pili http://home.biotec.or.th/NewsCenter/my_documents/my_pictures/F7AFD_plasmid.jpg http://kconline.kaskaskia.edu/bcambron/Biology%20117/Cells_files/image002.jpg

  6. Characteristics of all bacteria: Structure cont’d • Cell walls contain peptidoglycan which give it strength • Some surrounded by capsule which provides protection

  7. Characteristics of all bacteria: Structure cont’d • 3 shapes: • coccus (pl. cocci) = round • bacillus (pl. bacilli) = rod-shaped • spirillum (pl. spirilla)= spiral http://shorewoodscience.com/images/bacteria_shapes.gif

  8. Characteristics of all bacteria: Metabolism • Some autotrophic (via photosynthesis or chemosynthesis), some heterotrophic • Some obligate aerobes (can’t live without oxygen); some facultative aerobes (can live with or without oxygen); some obligate anaerobes (can’t live with oxygen)

  9. Characteristics of all bacteria: Reproduction • most reproduce asexually by binary fission • In most cases, daughter cells are genetically identical to parent cell • Mutations occur occasionally (1000 times as much as eukaryotic gene) which creates genetically different offspring

  10. Characteristics of all bacteria: Reproduction cont’d • Some undergo sexual reproduction in process called conjugation in which two cells join to exchange genetic information http://upload.wikimedia.org/wikipedia/commons/0/0a/Bacterial_Conjugation_en.png

  11. Characteristics of all bacteria: Reproduction cont’d • Transformation is when bacteria takes in and uses pieces of DNA from its environment (when DNA from other species, called horizontal gene transfer) http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2003/Siegenthaler/fig2.gif

  12. Characteristics of all bacteria: reproduction • Some bacteria are able to use endospores: structure which forms around nucleus during unfavourable environmental conditions http://www.apsnet.org/edcenter/illglossary/Pages/E-H.aspx

  13. Bacterial Diseases • Cause many diseases (range in severity of symptoms similar to viral diseases) • Ex. Cholera, diptheria, lyme disease, pertussis, tetanus, botulism • Some cause disease by producing and releasing toxins (ex. Botulism) • Some contain toxins that aren’t released until cell dies (ex. E. coli)

  14. Antibiotics and Antibiotic Resistance • Antibiotics are substances used to destroy bacteria • Antibiotic resistance is caused when antibiotics are overused or used improperly

  15. Antibiotic resistance http://upload.wikimedia.org/wikipedia/commons/thumb/f/f6/Antibiotic_resistance.svg/300px-Antibiotic_resistance.svg.png

  16. Domain Archaea (Kingdom Archaebacteria) • Live in extreme environments, most without oxygen, possibly conditions that were similar to those when life first evolved on Earth • See Table 3 on p. 52 for examples http://facstaff.uww.edu/wentzl/blacksmoker.jpg

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