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 are need oxygen facultative aerobes can live with or without oxygen obligate anaerobes are poisoned by oxygen
plasmid (circular DNA) flagellum Pili (genetic exchange) 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 (circular DNA) flagellum Pili (genetic exchange)
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, contain entirely different lipids than Eubacteria. ***Eubacteria is actually evolutionary older than Archeabacteria
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
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-positive stains purple, more peptidoglycan gram-negative stains pink, less 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. Prokaryotes exchange genes using pili conjugation bridge TEM; magnification 6000x
Other forms of genetic exchange Transduction: exchange of genes using a virus Transformation: endocytosis of DNA
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 Sterilize versus disinfect?
Prokaryotes provide nutrients to humans and other animals. Prokaryotes live in digestive systems of animals. make vitamins and medicines break down food fill niches (role in ecosystem)
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 (make it useable)
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 (poison released by an organism)
Normally harmless bacteria can become destructive. immune system may be lowered
Ex. Tuberculoses (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
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 (circular DNA). 2. Copy of the plasmid is transferred through conjugation (using pili). 3. Resistance is quickly spread through many bacteria.