1 Chapter 19 Bacteria & Viruses

2 19–1 Bacteria Prokaryote = single-celled organism lacking a nucleusProkaryote = single-celled organism lacking a nucleus 1 to 5 micrometers1 to 5 micrometers Epulopiscium fishelsoniEpulopiscium fishelsoni

3 Classifying Prokaryotes Monera  eubacteria and archaebacteriaMonera  eubacteria and archaebacteria Eubacteria: - Larger kingdom, live almost everywhereEubacteria: - Larger kingdom, live almost everywhere E. Coli

4 lack peptidoglycan different membrane lipids the DNA sequences of key archaebacterial genes are more like those of eukaryotes than those of eubacteria Live in extreme environments Archaebacteria

5 Identifying Prokaryotes Identified by:Identified by: –shape –the chemical nature of their cell walls –the way they move –the way they obtain energy

6 Shapes Shapes Rod-shaped prokaryotes are called bacilli (singular:bacillus).Rod-shaped prokaryotes are called bacilli (singular:bacillus). Spherical prokaryotes are called cocci (singular: coccus).Spherical prokaryotes are called cocci (singular: coccus). Spiral and corkscrew-shaped prokaryotes are called spirilla (singular: spirillum).Spiral and corkscrew-shaped prokaryotes are called spirilla (singular: spirillum).

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8 Cell Walls & Movement Cell Walls:Cell Walls: – with or without peptidoglycan –Use violet and red stains to detect –Gram + (violet) = with –Gram – (red) = without Movement:Movement: –No movement –Flagella = whip like –lash, snake, or spiral forward –glide slowly along a layer of slimelike material they secrete

9 Metabolic Diversity Most heterotrophs, some autotrophsMost heterotrophs, some autotrophs Heterotrophs:Heterotrophs: –Chemoheterotroph - Most heterotrophic prokaryotes must take in organic molecules for both energy and a supply of carbon. –Photoheterotroph = organism that is photosynthetic but needs organic compounds as a carbon source

10 Autotrophs:Autotrophs: –Photoautotroph = organism that uses energy from sunlight to convert carbon dioxide and water to carbon compounds Ex: CyanobacteriaEx: Cyanobacteria –Chemoautotroph = organism that makes organic carbon molecules from carbon dioxide using energy from chemical reactions

11 Releasing Energy Releasing Energy Obligate aerobe = organism that requires a constant supply of oxygen in order to live “Obligated” means they are required to have or do something –Ex: Mycobacterium tuberculosis

12 Obligate anaerobe = organism that cannot live in the presence of oxygen. –ex: Clostridium botulinum grow in canned food that has not been properly sterilized

13 Facultative anaerobe = organism that can survive with or without oxygen “Facultative” means able to function in different ways depending on the environment –Ex: E. coli lives anaerobically in the large intestine and aerobically in sewage or contaminated water

14 Growth and Reproduction Binary Fission = type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells

15 Conjugation = form of sexual reproduction in which paramecia and some prokaryotes exchange genetic information

16 Spore Formation = When growth conditions become unfavorable, many bacteria form structures called spores – endospore = type of spore formed when a bacterium produces a thick internal wall that encloses its DNA and a portion of its cytoplasm remain dormant for months or even years conditions improve, the endospore will germinate survive harsh conditions

17 Endospores

18 Nitrogen Fixers = bacteria nitrogen fixation = process of converting nitrogen gas into ammonia

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20 The Role of Microorganisms in Maintaining Equilibrium in the Environment

21 Importance of bacteria Bacteria are vital to maintaining the living world.

22 Helpful Bacteria Decomposers break down dead organic material Biotechnology - inserting helpful genes into a plasmid Bioremediation - bacteria eat up oil spills Food production Put nitrogen back into the soil Aid in digestion

23 Importance of Bacteria MANY uses!! Decomposers - bacteria help the ecosystem recycle nutrients; sewage treatment

24 Importance of bacteria Some are producers that capture energy by photosynthesis.

25 Importance of bacteria Others are decomposers breaking down nutrients in dead matter. Bacteria breakdown dead and decaying organisms. Help to recycle nutrients – which helps to maintain equilibrium in the environment.

26 Importance of bacteria Bacteria are also used to make some foods such as: pickles, ice cream, yogurt, and other things. Cheese: Bacteria produce lactic acid, which initially thickens the milk; bacteria also determine the flavor of the cheese later in the ripening process. Bread (leavened): Made using yeast, although the byproducts of the yeast’s fermentation of the dough are water and carbon dioxide (not alcohol), which fills the dough with air bubbles that make it rise Pickles: Cucumbers are fermented using lactic acid producing bacteria, giving pickles their sour taste and also preventing harmful strains of bacteria from taking hold. Microbes used: Enterobacter aerogenes, Lactobacillus brevis and L. plantarum, Leuconostoc mesenteroides, Pediococcus cerevisiae, Enterococcus faecalis Olives: Basically inedible until they are fermented, olives are also fermented using lactic acid producing bacteria, including Lactobacillus brevis, Lactobacillus plantarum. and Leuconostoc Yogurt: Bacteria added to milk produce lactic acid that makes the yogurt sour and partially breaks down the lactose in the milk. Microbes used: Lactobacillus bulgaricus and/or acidophilus & Streptococcus thermophilus