Domains and Kingdoms
The 3 Domains of Life
• Bacteria thought to be the oldest domain
– Prokaryote
• Archaea is next oldest
– Prokaryote
• Eukarya contains the 4 eukaryotic kingdoms
– Animals
– Fungi
– Plants
– Protists
• Very diverse group (p. 413 – fig. 2)
The Domain Bacteria
• Contains a single kingdom called eubacteria
• Most abundant organisms on earth
• Prokaryotes
• Bacteria found in practically every
environment on Earth
Characteristics of Bacteria
• Cell Wall
– Strong, exterior cell walls made of peptidoglycan
• Gene Translation Apparatus
– Amino acid sequences and RNA polymerases found in
bacteria differ from those found in eukaryotes and
archaeabacteria
– This information can be used to determine evolutionary
relationships of groups of bacteria
Kinds of Bacteria
• Wide range of bacteria exists
– Disease-causing
– Food-processing
– Control agricultural pests
– Perform genetic engineering
– Producers
– Consumers
The Domain Archaea
• Contains only 1 kingdom
– Archaeabacteria
• Prokaryotes
• Diverged from bacteria
• Can maintain life in a variety of environments
Characteristics of Archaeabacteria
• Cell Wall and Membrane
– Differ from bacteria (no peptidoglycan)
– Contain lipids, very different from bacteria and
eukaryotes
• Gene Structure and Translation
– Genes of archaea interrupted by introns
– Ribosomal proteins similar to eukaryotes and
different from bacteria
Kinds of Archaeabacteria
• Methanogens
– Obtain energy by combining hydrogen gas and carbon dioxide to
form methane gas
– Live in deep mud of swamps and poisoned by oxygen
• Extremophiles
– Thermophiles
• Live in extreme heat (up to 106 degrees C)
– Halophiles
• Live in extremely salty environments
– Some also live in extremely acidic conditions
• Non-extreme Archaeabacteria
– Grow in all the same environments as bacteria
The Domain Eukarya
• Made up of 4 kingdoms
– Protista
– Fungi
– Plantae
– Animalia
• Eukaryotes
• Early eukaryotes led to multicellular life
Characteristics of Eukarya
• Highly Organized Cell Interior
– Have nucleus and other internal compartments
– Allows cell to perform a variety of functions
• Multicellularity
– Activities of individual cells are coordinated with other cells
• Sexual Reproduction
– Life cycle involves sexual reproduction
– Mitosis
– Meiosis
Kinds of Eukaryotes
• Protista
– Contain multi and unicellular
organisms
– Aquatic
• Fungi
– Heterotrophs
– Mostly multicellular
– Live on and decompose
dead organisms
• Plants
– Multicellular
– Autotrophs
– Cell wall of cellulose
• Animals
– Heterotrophs
– No cell walls
– Tissue and organs
• p. 417 – Table 1