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.