Chapter 18 Bacteria

Concept Map Section 19-1 Bacteria Go to Section: are classified into the kingdoms of Eubacteria Archaebacteria include a variety of lifestyles such as live in harsh environments such as Infecting large organisms Thick mud Living in soil Animal digestive tracts Salty lakes Hot springs Go to Section:

Bacteria are part of two kingdoms: Archaebacteria Eubacteria The larger of the two kingdoms prokaryotes Cell walls contain peptidoglycan

Archaebacteria Prokaryotes, although the DNA are more like those of eukaryotes than eubacteria Cell walls lack peptidoglycan Membrane lipids are different than those of eubacteria Many scientists think that archaebacteria may be the ancestors of eukaryotes

Archaebacteria (cont.) Many archaebacteria live in harsh environments Methanogens – produce methane gas Extreme halophiles – salt-loving archaebacteria Thermoacidophiles – live in extremely acidic environments that have extremely high temperatures, like hot springs

Identifying Prokaryotes Shape Bacilli – rod-shaped Cocci- spherical Spirilla – spiral and corkscrew shaped

Identifying Prokaryotes (cont.) Cell walls Two different types of cell walls in eubacteria The Gram stain is used to tell them apart Gram-positive – stain purple Gram-negative – stain red/pink

Identifying Prokaryotes (cont.) Movement flagella- whip-like structures used for movement Other prokaryotes lash, snake, or spiral forward Some other prokaryotes glide slowly along slime they produce Many prokaryotes do not move at all

Obtaining Energy Autotrophs – produce their own food Photoautotrophs – use light for the energy source Example: cyanobacteria Chemoautotrophs – obtain energy from inorganic molecules (such as ammonia) Heterotrophs – obtain energy by the food it consumes Photoheterotrophs – obtain energy from light and also from inorganic molecules

Releasing Energy Cellular respiration – requires oxygen Called obligate aerobes Fermentation – does not require oxygen Called obligate anaerobes Some bacteria can survive with or without oxygen Called facultative anaerobes

Growth and Reproduction Replicates DNA and simply divides in half (asexual reproduction) Binary fission Some bacteria can transfer genetic material from one cell to another Conjugation When growth conditions become unfavorable, some bacteria form endospores to protect their genetic material

Bacteria in Nature Decomposers – bacteria act as “recyclers Nitrogen fixation Convert nitrogen from N2 into a form that plants can use Bacteria and Disease – disease causing bacteria are called pathogens Bacteria cause disease in one of two ways Damage tissues by breaking them down for food Release toxins (poisons) that harm the body Antibiotics can be used to kill bacteria

Common Diseases Caused by Bacteria Section 19-2 Disease Pathogen Prevention Tooth decay Lyme disease Tetanus Tuberculosis Salmonella food poisoning Pneumonia Cholera Streptococcus mutans Borrelia burgdorferi Clostridium tetani Mycobacterium tuberculosis Salmonella enteritidis Streptococcus pneumoniae Vibrio cholerae Regular dental hygiene Protection from tick bites Current tetanus vaccination Vaccination Proper food-handling practices Maintaining good health Clean water supplies Go to Section:

Any Questions ?