chapter 18.2: archaebacteria and eubacteria
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Chapter 18.2: Archaebacteria and Eubacteria. AE/P/FPA. Brief Comparison. Bacteria Structure. Same as most prokaryotic cells and it has a cell wall Cell wall is important because it prevents bacterial cell from bursting - PowerPoint PPT PresentationTRANSCRIPT
Chapter 18.2: Archaebacteria and Eubacteria
AE/P/FPA
Brief Comparison
Archaebacteria Both Eubacteria
-Cell wall has no peptidoglycan-has a unique DNA
-Prokaryotic-Unicellular-autotrophic and heterotrophic
-cell wall has peptidoglycan-heterotrophic photosynthetic (cyanobacteria)-heterotrophic chemosynthetic (nitrogen-fixing bacteria)
Bacteria Structure
• Same as most prokaryotic cells and it has a cell wall
• Cell wall is important because it prevents bacterial cell from bursting– Most cells naturally take on water by osmosis; live
in a hypotonic solution
Bacteria Identification
• “Gram-Staining”– Reflects a difference in cell walls (they also will
react to different antibiotics)• Gram positive = turns purple when stained• Gram negative = turns pink when stained
Bacteria Identification
• Shape– 1. spheres = “cocci”– 2. rods = “bacilli”– 3. spirals = “spirilla”
• Good example of all 3 shapes can be seen in Fig 18.12 of our textbook
Bacteria Identification
• Arrangement– 1. Diplo = paired arrangement– 2. Staphylo = “grape” like arrangement– 3. Strepto = “chains of cells” arrangement
Bacteria Reproduction
• Asexual reproduction– “binary fission”
• Sexual reproduction– “ conjugation” with the use of a PILUS (“pili” =
plural form)
• Fig 18.13 and 18.14
Bacteria Reproduction:Binary Fission vs. Conjugation
Other terms to be familiar with
• Obligate Anaerobes– One of the first bacteria to evolve– Killed by oxygen– Release energy using fermentation
• Obligate Aerobes– Require oxygen for respiration– Release energy using cellular respiration
Bacteria Survival Mechanism
• Endospore– A tiny structure that contains a bacteriums DNA
and a small amount of its cytoplasm, encased by a tough outer covering the resists temperature extremes and harsh chemicals
– Protects the DNA during “hard times”– Botulism can be caused by an endospore of B.
botulinum germinates
Bacteria Survival Mechanisms
• Toxin– Poison produced by a bacterium
The Importance of Bacteria
• Nitrogen fixation– Taking nitrogen from atmosphere and putting it
into a form plants can use
• Recycling of nutrients (decomposers)• Foods and medicines• Bacteria cause Disease– Now due to development of better antibiotics, the
average human life expectancy has increased to 75 years old
TODAYS ASSIGNMENT
• Homework over the weekend:– 18.2 Reinforcement and Study Guide– My suggestion is that you complete it here while
you have 30 minutes left in class.