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