18 4 Bacteria and Archaea KEY CONCEPT Bacteria

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18. 4 Bacteria and Archaea KEY CONCEPT Bacteria and archaea are both single-celled prokaryotes.

18. 4 Bacteria and Archaea KEY CONCEPT Bacteria and archaea are both single-celled prokaryotes.

18. 4 Bacteria and Archaea Prokaryotes are widespread on Earth. • Prokaryotes can be

18. 4 Bacteria and Archaea Prokaryotes are widespread on Earth. • Prokaryotes can be grouped by their need for oxygen. – obligate anaerobes are poisoned by oxygen – obligate aerobes need oxygen – facultative aerobes can live with or without oxygen

18. 4 Bacteria and Archaea Bacteria and archaea are structurally similar but have different

18. 4 Bacteria and Archaea Bacteria and archaea are structurally similar but have different molecular characteristics. • Bacteria commonly come in three forms. – rod-shaped, called bacilli – spiral, called spirilla or spirochetes – spherical, called cocci Lactobacilli: rod-shaped Enterococci: spherical • Archaea have many shapes. Spirochaeta: spiral

18. 4 Bacteria and Archaea examples

18. 4 Bacteria and Archaea examples

18. 4 Bacteria and Archaea

18. 4 Bacteria and Archaea

18. 4 Bacteria and Archaea • Bacteria and archaea have similar structures. – plasmid

18. 4 Bacteria and Archaea • Bacteria and archaea have similar structures. – plasmid – flagellum pili plasma – pili membrane chromosome cell wall plasmid This diagram shows the typical structure of a prokaryote. Archaea and bacteria look very similar, although they have important molecular differences. flagellum

18. 4 Bacteria and Archaea • Bacteria and archaea have molecular differences. – The

18. 4 Bacteria and Archaea • Bacteria and archaea have molecular differences. – The amount of peptidoglycan within the cell wall can differ between bacteria GRAM NEGATIVE GRAM POSITIVE – Archaea have different lipids entirely – Bacteria: have peptidoglycan in cell walls – Archaea: no peptidoglycan in cell walls

18. 4 Bacteria and Archaea • Gram staining identifies bacteria. – stains polymer peptidoglycan

18. 4 Bacteria and Archaea • Gram staining identifies bacteria. – stains polymer peptidoglycan – gram-positive stains purple, more peptidoglycan – gram-negative stains red, 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.

18. 4 Bacteria and Archaea Bacteria have various strategies for survival. • Prokaryotes exchange

18. 4 Bacteria and Archaea Bacteria have various strategies for survival. • Prokaryotes exchange genes conjugation bridge during conjugation. • Bacteria may survive by forming endospores. TEM; magnification 6000 x

18. 4 Bacteria and Archaea Anthrax – forms endospores

18. 4 Bacteria and Archaea Anthrax – forms endospores