KEY CONCEPT Kingdoms Eubacteria and Archaeabacteria are composed of single-celled prokaryotes.

Prokaryotes are widespread on Earth. Prokaryotes can be grouped by their need for oxygen. obligate aerobes need oxygen facultative aerobes can live with or without oxygen obligate anaerobes are poisoned by oxygen

Eubacteria and Archaebacteria are structurally similar but have different molecular characteristics. flagellum pili plasmid cell wall chromosome plasma membrance This diagram shows the typical structure of a prokaryote. Archaea and bacteria look very similar, although they have important molecular differences. plasmid flagellum pili

Domain Archaea, Kingdom Archaebacteria Archaebacteria are typically obligate anaerobes. Live in extremely harsh environments, ex.stomachs of cows, high salt concentrated areas such as the Dead Sea and in sulfur springs or deep sea vents. Divided into 3 groups: methanogens (methane producers, halophiles (salt loving) and thermophiles (heat loving) Come in a variety of shapes, similar to Eubacteria. There is no peptidoglycan in their cell walls, and they contain entirely different lipids than Eubacteria.

Domain Bacteria, Kingdom Eubacteria Eubacteria commonly come in three forms. rod-shaped, called bacilli spiral, called spirilla or spirochetes spherical, called cocci Lactobacilli: rod-shaped Spirochaeta: spiral Enterococci: spherical

Eubacteria groups (prefixes describe bacteria) Diplo: two Staphlo: cluster Strepto: chain Ex. Diplococcus Ex. Staphlospirlli Ex. Streptobacillus

Gram negative has extra outer membrane Eubacteria The amount of peptidoglycan within the cell wall can differ between Eubacteria: Gram negative has extra outer membrane Gram positive cell wall just peptidoglycan GRAM NEGATIVE GRAM POSITIVE

Gram staining identifies bacteria. stains polymer peptidoglycan gram-negative stains pink, less (very little) peptidoglycan gram-positive stains purple, more (large amounts) peptidoglycan Gram-negative bacteria have a thin layer of peptidoglycan and stain red. Gram-positive bacteria have a thicker peptidoglycan layer and stain purple.

Bacteria have various strategies for survival. Form of genetic recombination is conjugation. transfer of genetic material (exchanging of genes) between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells conjugation bridge TEM; magnification 6000x

Other forms of genetic exchange Transduction Transduction: exchange of genes using a virus, does not require cell-to-cell contact like conjugation. Transformation: endocytosis of free-floating DNA outside the cell. Transformation

Bacteria survival Bacteria may survive by forming endospores. Resistant to most cleaning agents and temperature changes Creates double membrane around DNA to survive harsh conditions

Prokaryotes provide nutrients to humans and other animals. Prokaryotes live in digestive systems of animals. make vitamins break down food fill niches

Bacteria help ferment many foods. yogurt, cheese pickles, sauerkraut soy sauce, vinegar

Prokaryotes play important roles in ecosystems. Prokaryotes have many functions in ecosystems. photosynthesize recycle carbon, nitrogen, hydrogen, sulfur fix nitrogen

Bioremediation uses prokaryotes to break down pollutants. oil spills biodegradable materials

Some bacteria cause disease. Bacteria cause disease by one of two methods: invading tissues making toxins. A toxin is a poison released by an organism.

Normally harmless bacteria can become destructive. immune system may be lowered

Ex. Tuberulosis (Mycobacterium tuberculosis) Bacteria multiply in the lungs, killing WBCs Host releases histamines which cause swelling

Ex. Staph poisoining (Staphylococcus aureus) Food poisoning caused by mishandling of food Infection of the skin

Ex. Botulism (Clostridium botulinum) Improperly canned foods contaminated with endospores

Ex. Flesh eating bacteria (Streptococci) Colonize tissue through cut or scrape

Controlling bacteria Physical Removal Washing hands or other surfaces with soap under running water doesn’t kill pathogens, but it helps dislodge both bacteria and viruses. Disinfectants Chemical solutions that kill bacteria can be used to clean bathrooms, kitchens, hospital rooms, and other places where bacteria may flourish.

Food Storage Low temperatures, like those inside a refrigerator, will slow the growth of bacteria and keep most foods fresher for a longer period of time than possible at room temperature. Food Processing Boiling, frying, or steaming can sterilize many kinds of food by raising the temperature of the food to a point where bacteria are killed.

Sterilization by Heat Sterilization of objects such as medical instruments at temperatures well above 100° Celsius can prevent the growth of potentially dangerous bacteria. Most bacteria cannot survive such temperatures.

Preventing Bacterial Diseases Many bacterial diseases can be prevented by stimulating the body’s immune system with vaccines. A vaccine is a preparation of weakened or killed pathogens or inactivated toxins. When injected into the body, a vaccine prompts the body to produce immunity to a specific disease. Immunity is the body’s ability to destroy pathogens or inactivated toxins.

Treating Bacterial Diseases A number of drugs can be used to attack a bacterial infection. These drugs include antibiotics--such as penicillin and tetracycline--that block the growth and reproduction of bacteria. Antibiotics disrupt proteins or cell processes that are specific to bacterial cells. In this way, they do not harm the host’s cells. Antibiotics are not effective against viral infections.

Antibiotics are used to fight bacterial disease. Antibiotics may stop bacterial cell wall formation. Their role is to interfere with the ability of the bacteria’s reproduction process.

Overuse of Antibiotics Bacteria become resistant due to exposure Underuse of Antibiotics Kill the weak bacteria while stronger bacteria become resistant Misuse of Antibiotics Viruses cannot be treated with antibiotics, allowing normal bacteria to become resistant or killing them

Bacteria can evolve resistance to antibiotics. 1. Bacterium carries genes for antibiotic resistance on a plasmid. 2. Copy of the plasmid is transferred through conjugation. 3. Resistance is quickly spread through many bacteria.