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

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Presentation on theme: "18.4 Bacteria and Archaea KEY CONCEPT Kingdoms Eubacteria and Archaeabacteria are composed of single-celled prokaryotes."— Presentation transcript:

1 18.4 Bacteria and Archaea KEY CONCEPT Kingdoms Eubacteria and Archaeabacteria are composed of single-celled prokaryotes.

2 18.4 Bacteria and Archaea 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

3 18.4 Bacteria and Archaea 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)

4 18.4 Bacteria and Archaea 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

5 18.4 Bacteria and Archaea Eubacteria commonly come in three forms. –rod-shaped, called bacilli Lactobacilli: rod-shapedSpirochaeta: spiral – spiral, called spirilla or spirochetes – spherical, called cocci Enterococci: spherical Domain Bacteria, Kingdom Eubacteria

6 18.4 Bacteria and Archaea Eubacteria groups (prefixes describe bacteria) Diplo: two Staphlo: cluster Strepto: chain Ex. Diplococcus Ex. Staphlospirlli Ex. Streptobacillus

7 18.4 Bacteria and Archaea Eubacteria GRAM NEGATIVEGRAM POSITIVE –The amount of peptidoglycan within the cell wall can differ between Eubacteria: Gram negative has extra outer membrane, Gram positive cell wall just peptidoglycan

8 18.4 Bacteria and Archaea Gram staining identifies bacteria. Gram-negative bacteria have a thin layer of peptidoglycan and stain red. Gram-positive bacteria have a thicker peptidoglycan layer and stain purple. –stains polymer peptidoglycan –gram-positive stains purple, more peptidoglycan –gram-negative stains pink, less peptidoglycan

9 18.4 Bacteria and Archaea Bacteria have various strategies for survival. Form of genetic recombination is conjugation. –Prokaryotes exchange genes using pili conjugation bridge TEM; magnification 6000x

10 18.4 Bacteria and Archaea Other forms of genetic exchange Transduction: exchange of genes using a virus Transformation: endocytosis of DNA

11 18.4 Bacteria and Archaea 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?

12 18.4 Bacteria and Archaea 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)

13 18.4 Bacteria and Archaea Bacteria help ferment many foods. –yogurt, cheese –pickles, sauerkraut –soy sauce, vinegar

14 18.4 Bacteria and Archaea Prokaryotes play important roles in ecosystems. Prokaryotes have many functions in ecosystems. –photosynthesize –recycle carbon, nitrogen, hydrogen, sulfur –fix nitrogen (make it useable)

15 18.4 Bacteria and Archaea Bioremediation uses prokaryotes to break down pollutants. –oil spills –biodegradable materials

16 18.4 Bacteria and Archaea Some bacteria cause disease. Bacteria cause disease by one of two methods: –invading tissues – making toxins ( poison released by an organism)

17 18.4 Bacteria and Archaea –immune system may be lowered Normally harmless bacteria can become destructive.

18 18.4 Bacteria and Archaea Ex. Tuberculoses (Mycobacterium tuberculosis) Bacteria multiply in the lungs, killing WBCs Host releases histamines which cause swelling

19 18.4 Bacteria and Archaea Ex. Staph poisoining (Staphylococcus aureus) Food poisoning caused by mishandling of food Infection of the skin

20 18.4 Bacteria and Archaea Ex. Botulism (Clostridium botulinum) Improperly canned foods contaminated with endospores

21 18.4 Bacteria and Archaea Ex. Flesh eating bacteria (Streptococci) Colonize tissue through cut or scrape

22 18.4 Bacteria and Archaea 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.

23 18.4 Bacteria and Archaea Overuse of Antibiotics Bacteria become resistant due to exposure Kill the weak bacteria while stronger bacteria become resistant Underuse of Antibiotics Misuse of Antibiotics Viruses cannot be treated with antibiotics, allowing normal bacteria to become resistant or killing them

24 18.4 Bacteria and Archaea 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.


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