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Bacteria. Classifying Bacteria. Bacteria - general term used to describe prokaryotes Prokaryotes are unicellular organisms that lack a nucleus and membrane bound organelles Prokaryotes are divided into 2 kingdoms: eubacteria and archaebacteria . Eubacteria.
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Classifying Bacteria • Bacteria - general term used to describe prokaryotes • Prokaryotes are unicellular organisms that lack a nucleus and membrane bound organelles • Prokaryotes are divided into 2 kingdoms: eubacteria and archaebacteria.
Eubacteria • “True” bacteria - the most common bacteria. • Contain a cell wall made of a carbohydrate - peptidoglycan. • Ex: E. coli, Streptococcus, Chlamydia, Gonnorhea, Antrasis, C. botulinum
Ribosome Cell wall Cell membrane Peptidoglycan Pili – cell to cell contact Flagellum for movement DNA The Structure of a Eubacterium
Archaebacteria • Live in harsh conditions: • methanogens - no O2 – thick mud, digestive tracts of animals • halophytes - salty environments, hot springs • thermophiles – extremely hot environments • No peptidoglycan, different membrane lipids, different DNA sequence than eubacteria.
Identifying Factors of Bacteria • Shape • Cell Wall • Movement
Identifying Factors of Bacteria • Shape: • cocci – round • bacilli – rod-shaped • spirilla – spiral / corkscrew
Identifying Factors of Bacteria • Cell Wall: • Gram-positive - contain peptidoglycan (violet) • Gram-negative - no peptidoglycan (pink)
Identifying Factors of Bacteria • Movement • No movement • Movement – with flagella, spiral motion or slime layer
Metabolism • Heterotrophs • Chemoheterotrophs– take in food for energy and carbon. • Photoheterotrophs – is photosynthetic but needs organic compounds for carbon.
Metabolism • Autotrophs • Chemoautotrophs – make carbon molecules from CO2 using energy from chemical reactions • Photoautotrophs– use sunlight to change CO2 and water to carbon compounds
Releasing Energy • Bacteria release energy through cellular respiration, fermentation or both. • Obligate aerobes – require a constant supply of oxygen (ex: Mycobacterium tuberculosis) • Obligate anaerobes – must live in absence of oxygen (ex: Clostridium botulinum) • Facultative anaerobes – neither require nor are harmed by O2. (ex: E. coli)
Growth and Reproduction • Binary fission (asexual) – bacterium grows, replicates DNA, divides in half. Produces identical cells. • Conjugation (sexual) – hollow bridge forms between 2 bacteria cells, genetic material is transferred.
Spore Formation – unfavorable conditions endospores form enclosing the DNA. In favorable conditions, they germinate and grow.
Important Uses of Bacteria • Decomposers – break down deadorganisms, waste and sewage treatment plants. • Nitrogen Fixers – convert nitrogen gas to nitrogen compounds plants can use. • Human Use – food, beverages, clean up oil spills, medicine, intestinal tract.