✧ chp 8 - bacteria

• Bacteria are prokaryotic cells that lack membrane-bound organelles.
• study of bacteria is called as bacteriology
• based on their shape they are of four types
• bacillus is rod shaped
• spirillum is spiral in shape
• vibrio is a comma shaped bacteria
• bacterias which can change their shape and structure according to the environmental conditions and nutrition availability are called as pleomorphic bacteria.
• acetobacter is a pleomorphic bacteria
• photo autotrophs

  source of energy is sunlight

  source of carbon is atmospheric co2
• chlorobium and chromatium are photo auto trophs
• chemo autotrophs

  source of energy is inorganic substances

  source of carbon is co2
• nitrosomonas and nitrobacter are chemo auto trophs
• photo heterotrophs

  source of energy is sunlight

  source of carbon is organic substances
• rhodospirillum and rhodopsuedomonas are photo heterotrophs
• chemo heterotrophs

  source of energy and carbon is organic chemicals

  they are of 2 types : saprophytes and parasites.
• saprophytes - feeds on dead and decayed matter

  eg - bacillus
• parasites - lives on living cells and tissues

  eg - salmonella, xanthomonas
• conjugation was observed by lederberg and tatum in escherchia coli cells
• in conjugation , the donor cell transfers genetic material to recipient cell through pilus