Presentation on theme: "KEY CONCEPT Bacteria and archaea are both single-celled prokaryotes."— Presentation transcript:
1KEY CONCEPT Bacteria and archaea are both single-celled prokaryotes.
2Prokaryotes are widespread on Earth. Prokaryotes can be grouped by their need for oxygen.obligate anaerobes are poisoned by oxygenobligate aerobes need oxygenfacultative aerobes can live with or without oxygen
3Bacteria commonly come in three forms. rod-shaped, called bacilli Bacteria and archaea are structurally similar but have different molecular characteristics.Bacteria commonly come in three forms.rod-shaped, called bacillispiral, called spirilla or spirochetesspherical, called cocciLactobacilli: rod-shapedSpirochaeta: spiralEnterococci: sphericalArchaea have many shapes.
4Bacteria and archaea have similar structures. plasmid flagellum pili cell wallchromosomeplasma membranceThis diagram shows the typical structure of a prokaryote. Archaea and bacteria look very similar, although they have important molecular differences.
5Bacteria and archaea have molecular differences. The amount of peptidoglycan within the cell wall can differ between bacteriaGRAM NEGATIVEGRAM POSITIVEArchaea have different lipids entirely
6Gram staining identifies bacteria. stains polymer peptidoglycan gram-positive stains purple, more peptidoglycangram-negative stains pink, less peptidoglycanGram-negative bacteria have a thin layer of peptidoglycan and stain red.Gram-positive bacteria have a thicker peptidoglycan layer and stain purple.
7Bacteria have various strategies for survival. Prokaryotes exchange genes during conjugation.conjugation bridgeTEM; magnification 6000xBacteria may survive by forming endospores.
8KEY CONCEPT Prokaryotes perform important functions for organisms and ecosystems.
9Prokaryotes provide nutrients to humans and other animals. Prokaryotes live in digestive systems of animals.make vitaminsbreak down foodfill niches
10Bacteria help ferment many foods. yogurt, cheesepickles, sauerkrautsoy sauce, vinegar
11Prokaryotes play important roles in ecosystems. Prokaryotes have many functions in ecosystems.photosynthesizerecycle carbon, nitrogen, hydrogen, sulfurfix nitrogen
12Bioremediation uses prokaryotes to break down pollutants. oil spillsbiodegradable materials
13KEY CONCEPT Understanding bacteria is necessary to prevent and treat disease.
14Some bacteria cause disease. Bacteria cause disease by invading tissues or making toxins.A toxin is a poison released by an organism.
15Normally harmless bacteria can become destructive. may colonize new tissues
16Normally harmless bacteria can become destructive. immune system may be lowered
17Antibiotics are used to fight bacterial disease. Antibiotics may stop bacterial cell wall formation.Antibiotics do not work on viruses.Prevention is best method to fight bacterial disease.
18Bacteria can evolve resistance to antibiotics. Bacteria are gaining resistance to antibiotics.A bacterium carries genes for antibiotic resistance on a plasmid.A copy of the plasmid is transferred through conjugation.Resistance is quickly spread through many bacteria.overuseunderusemisuseAntibiotics must be used properly.