1. Chapter 20 Section 1 Bacteria

2. There are two major groups of bacteria
Two Types of Bacteria
There are two major groups of bacteria
Domain Archae
Domain Bacteria

3. Archeabacteria Older than eubacteria
Contain unusual lipids in cell wall and introns in their DNA- both are lacking in eubacteria
Known for living in extreme conditions
Examples:
Methanogens: anaerobes that make energy by converting H2 and CO2 into methane gas
Extreme halophiles: thrive in environments w/high salt content. They use salt to make ATP
Thermoacidophiles: live in highly acidic, hot environments.

4. Eubacteria Most known prokaryotes are members of the Domain Bacteria.
Found everywhere
Occur in three shapes
Cocci (pl) Coccus (sing) are spherical or round in shape
Bacilli (pl) Bacillus (sing) are rod shaped
Spirilli (pl) Spirillus (sing) are cork screw shaped

5. The Gram Stain
Bacteria are classified partly due to the way that they react to a Gram Stain
Gram positive bacteria dye purple (they have a thick layer of peptidoglycan and no outer membrane)
Gram negative bacteria dye pink/red (they have a thin layer of peptidoglycan and have an outer membrane)
Gram positive bacteria and Gram negative bacteria differ in their cell wall structure. This difference impacts which stain they will absorb.

6. Obtaining Energy Some bacteria are:
Photoautotrophic: use light to make energy, photosynthetic
Ex. Sulfur and nonsulfur bacteria and cyanobacteria
Chemoautotrophs: get there energy from inorganic sources
Heterotrophs: get there energy from other organisms. Heterotrophs can be broken down into:
Anaerobic: do not need oxygen to survive
Obligate anaerobes: will die if exposed to oxygen ex. methanogens
Obligate aerobes: require oxygen to survive ex. Tubercullosis (TB)
Facultative anaerobes: live w/ or w/o oxygen ex. E. coli

7. Prokaryote Reproduction
Reproduce through binary fission
Exchange of genetic material through conjugation, transformation, and transduction; and survive harsh conditions by forming endospores

8. Types of Genetic Recombination Reproduction
Transformation: In transformation a bacterial cell will take up free floating genetic material from the surrounding environment.
Conjugation: one bacteria shares genes contained in a plasmid with another bacteria through a pilus (sing) pili (pl)
Transduction: a virus takes up a piece of a host bacteria’s DNA during infection
When new viruses form they have the piece of bacterial DNA in their DNA
When the new viruses infect another DNA they will insert their new DNA along with the piece of bacterial DNA into the host bacteria
Transduction occurs during the lysogenic and lytic cycle of virus reproduction

9. Bacteria Toxins Two Types:
1. Endotoxins: are composed of lipids and carbohydrates. They are part of the cell membrane of Gram negative bacteria. They are released when the bacteria dies
Ex. E. coli causes illness through endotoxins
2. Exotoxins: are proteins produced by Gram positive bacteria
Ex. Diptheria causes illness by releasing exotoxins
Ex. Botulism causes illness by releasing exotoxins

10. Disease
Bacteria cause illness through toxins (endotoxins and exotoxins) and enzymes
Digestive enzymes are released by bacteria to open up tissue to further invasion
Ex. Streptococci (strep throat) releases enzymes that destroy blood clots

11. How do antibiotics work?
Antibiotics are chemicals that kill bacteria by interfering with their life functions (Table 24-5)
Penicillin inhibits cell wall synthesis
Rifampin interferes with RNA synthesis

12. Bacterial Resistance There are two main causes:
Antibiotics are prescribed for viral diseases
Anitibiotics are not used properly
Some bacteria possess a genetic mutation that renders them less susceptible to the antibiotics. These bacteria are said to be antibiotic resistant.

13. Good or Bad? Not all bacteria are bad
Some plants contain bacteria in their roots that fix nitrogen.
Legumes such as soy and peanuts have this ability
Bacteria are important in the process of decay
Bacteria play a necessary role in the creation of some food Ex. Yogurt, buttermilk, sauerkraut

14. Bacteria vs. Viruses Bacteria are: Viruses are: Living organisms
Capable of making or obtaining energy
Completely different in structure
Viruses are:
Not living organisms
Not capable of making or obtaining energy (they don’t need to)