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Notes 9-2. Bacteria. 2 Kingdoms. Most scientists agree that there are 2 Kingdoms of bacteria 1) Archaebacteria (very ancient) 2) Eubacteria (“true” bacteria). The Bacterial Cell. Prokaryotic (No nucleus, so genetic material and ribosomes are floating in cytoplasm) Circular DNA
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Notes 9-2 Bacteria
2 Kingdoms • Most scientists agree that there are 2 Kingdoms of bacteria • 1) Archaebacteria (very ancient) • 2) Eubacteria (“true” bacteria)
The Bacterial Cell • Prokaryotic (No nucleus, so genetic material and ribosomes are floating in cytoplasm) • Circular DNA • Cell walls • May have flagella
Discovery • Discovered in late 1600s by Anton van Leeuwenhoek using a microscope
Shapes of bacteria • 3 Shapes: 1) Spirilla are spiral, Bacilli are rod-like, and Cocci are circular • You can often tell the shape of the bacteria by its scientific name.
Bacillus Anthracis • Can you tell the shape of this bacteria by its name? It’s shape is bacilli or rodlike! This bacteria causes anthrax!
Streptococcus pyogenes • Can you tell the shape of this bacteria by its name? It’s shape is cocci or sperical! This is one of the bacterias that cause strep throat!
Living conditions • Many can survive harsh conditions by growing protective capsule called endospores inside • Some are autotrophs, they make their own food using sunlight or chemicals • Some are heterotrophs that consume food such as other living organisms or dead/ decaying matter • Some need oxygen and some do not, some will die in presence of oxygen!
Endospore • Protects DNA until environmental conditions are right for survival
Reproduction • Asexually by binary fission (cell copies its DNA, then splits into 2 identical cells) • Sexually by conjugation (bridge built between 2 bacteria and DNA is inserted, then divides asexually by binary fission, genetically different from parent cell)
Role in Nature • Release O2 gas into air we breathe • Both food production and spoilage • Environmental recycling (they’re decomposers like fungi) • Environmental cleaning • Some cause diseases, some used to make medicines • Found naturally in body and help many processes