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Prokaryotes
Learning Objectives Explain how prokaryotes are classified. Describe how prokaryotes vary in structure and function. Explain the role of prokaryotes in the living world.
Classifying Prokaryotes
• Unicellular
• No nucleus
• DNA in cytoplasm
• Bacteria or Archaea
Bacteria
Bacteria include a wide range of organisms; many phyla are needed to classify this group.
Archaea vs. Bacteria
Important differences:
• Cell walls
• Cell membranes
• DNA sequences
• Harsh environments
Prokaryotes: Size, Shape, and Movement
Prokaryotes vary in size, shape, and movement.
Bacilli Cocci Spirilla
• None• Propelled by flagella
• Glide on secretions
Prokaryotes: Nutrition and Metabolism
Prokaryotes: Nutrition and Metabolism
Prokaryotes: Reproduction and Change
Prokaryotes reproduce using binary fission.
conjugationendospore
Decomposers
By assisting in breaking down dead organisms, prokaryotes supply raw materials in the environment.
Bacteria of the genus Rhizobium
Bacteria of the genus Rhizobium
Cyanobacteria of the genus Anabaena
Cyanobacteria of the genus Anabaena
Bacteria called actinomycetes
Bacteria called actinomycetes
ProducersFood chains everywhere are dependent upon prokaryotes as producers of food and biomass.
Nitrogen Fixers
Nitrogen-fixing bacteria and archaea provide 90% of atmospheric nitrogen.
Prokaryotes Overview
Classification:•Bacteria
•Archaea
Classification:•Bacteria
•Archaea
• Diverse• Size
• Shape
• Movement
• Metabolism
• Diverse• Size
• Shape
• Movement
• Metabolism
Ecologically importantEcologically important