Bacteria
Prokaryotes
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Unicellular organisms that lack a nucleus and true organelles
Smallest of all the cells
Common term = Bacteria
A. Classifying Prokaryotes
1. Eubacteria – “true bacteria”; common, all around us
2. Archaebacteria – ancient Bacteria; extreme environments (hot, sulfur springs)
Common Diseases Caused by Bacteria
B. Structure of a Eubacterium
1.Cell Wall
2. Cell Membrane
3. Ribosome
4. Pili
5. DNA
6. Flagellum
C. Identifying Prokaryotes
1. Shapes
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Bacilli – rod shaped
Cocci – spherical
Spirilla – spiral shaped
2. Cells Walls – made of peptidoglycan
 Eubacteria – two types of cell walls
 Gram-positive – stain purple, stains the thick peptidoglycan cell walls
 Ex . Streptococcus
 Gram –negative – stain pink or light red,
 Ex. E. coli
3. Movement: Do they move or how they move?
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Propelled by flagella
Spiral forward
Glide along a layer of excreted slime
D. Obtaining Energy
1. Photoautotroph – photosynthetic prokaryotes (bacteria)
2. Chemoautotroph – energy from chemical reactions
3. Heterotroph – obtains energy from food it consumes (organic compounds)
4. Photoheterotroph – photosynthetic and needs organic compounds
E. Releasing Energy -Bacteria use cellular respiration, fermentation or both
1. Obligate Aerobes – need Oxygen (02) to live
2. Obligate Anaerobes - do not need Oxygen (02) and are poisoned by it
3. Facultative Anaerobes – do not require Oxygen (02) to live, but are not harmed by it either (live in our
gut)
F. Growth & Reproduction
1. Binary Fission = Asexual – double in size and DNA, split in half.
2. Conjugation = Sexual, two bacteria exchange genetic material – can create a new strain.
3. Spore Formation = Endospore -Formed during harsh conditions – hibernates until
conditions are good
Ex. Drought, extreme heat, no food, frozen food
G. Bacteria – Why do plants and animals need nitrogen?
1. Decomposers – break down organic matter
2. Nitrogen Fixers – converts nitrogen into a form plants can us N2 converted to NH3 (ammonia)
3. Bacteria & Disease – 2 ways!
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Damage the tissues to make food
Release toxins (poisons)
4. Human Uses of Bacteria - yogurt, cheese, mine minerals, oil spill cleanup, medicine etc.)
5. The Nitrogen Cycle
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Nitrogen is required to make proteins
Most of the nitrogen on Earth is in the air as N2
H. Controlling Bacteria
1. Sterilization by heat
2. Disinfectants
3. Food Storage and Processing
4. Antibiotics
5. Vaccines