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Chapter 19

Chapter 19. Bacteria and Viruses. 19-1 Bacteria Classifying Prokaryotes. Eubacteria - have cell walls with peptidoglycan , a carbohydrate Archaebacteria - have cell walls with out peptidoglycan -DNA is more similar to eukaryotes -live in harsh environments. Identifying Prokaryotes.

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Chapter 19

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  1. Chapter 19 Bacteria and Viruses

  2. 19-1 BacteriaClassifying Prokaryotes Eubacteria- have cell walls with peptidoglycan, a carbohydrate Archaebacteria- have cell walls with out peptidoglycan -DNA is more similar to eukaryotes -live in harsh environments

  3. Identifying Prokaryotes • Shape • Bacilli (rod shaped) • Cocci (spherical) • Spirilla (spiral and corkscrew)

  4. Identifying Prokaryotes • Cell Walls • Gram-positive: thick peptidoglycan walls • Gram-negative: think peptidoglycan walls • More resistant to antibiotics

  5. Identifying Prokaryotes • Movement • Some move (flagella) • Some don’t move

  6. Metabolic Diversity Heterotrophs Chemoheterotrophs- get carbon and energy from organic molecules Ex: humans Photoheterotrophs- get carbon from organic molecules, get energy from sunlight

  7. Metabolic Diversity Autotrophs Photoautotrophs- get carbon from CO2, get energy from sunlight Ex: cyanobacteria. Chemoautotrophs- get carbon from CO2, get energy from inorganic chemical reactions

  8. Metabolic Diversity

  9. Releasing Energy • Obligate aerobes- require oxygen Ex: Mycobacterium tuberculosis • Obligate anaerobes- do not require oxygen, oxygen kills them Ex: Clostridium botulinum • Faculatative anaerobes- live with or w/o oxygen Ex: E. coli

  10. Growth and Reproduction • Binary fission- parents splits into two daughter cells, asexual reproduction

  11. Growth and Reproduction • Conjugation- a pilus forms between two bacteria, DNA is transferred, sexual reproduction

  12. Growth and Reproduction • Spore Formation- Endospore- thick wall that protects a dormant bacterium

  13. Importance of Bacteria • Decomposers • Nitrogen Fixation • Taking nitrogen from the air and converting it to a useable form

  14. 19-2 Viruses Virus- composed of a DNA or RNA core surrounded by a capsid (protein coat)

  15. Viral Infection Lytic Infection- Virus enters the cells, copies itself, and causes the cell to burst

  16. Viral Infection Lysogenic Infection- virus enters the cell, integrates its DNA into the host DNA, it gets copied when the host replicates Prophage- viral DNA embedded in a host’s DNA

  17. Retroviruses • Genetic information is RNA • In the host RNA is copied to DNA (reverse transcription) • Examples: HIV

  18. Viroids and Prions • Viroids- effect plants, ssRNA w/o a capsid • Damage tomatoes, apples, potatoes • Prions- effect animals, protein infectious particles • Ex: mad cow disease, Creutzfeldt-Jakob disease

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