BIOL10004 Chapter Notes - Chapter 35: Anoxygenic Photosynthesis, Solar Irradiance, Phylogenetic Tree
29 Jun 2018
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Prokaryotes : Bacteria and Archaea ( Chapter 35: 861–866,
870)
True nucleus is absent in a prokaryote
Smallest cellular life on Earth
Ancient single-celled organisms with fossil record back 3.6 Billion years
Length of time allowed to evolve high diversity
Able to survive in wide range of environments
Evolution and diversity of bacteria
Prokaryotes were the first cellular life on earth
Earliest microscopic cellular life resembled modern bacteria
Continued to evolved for 2 billion years
Eukaryotes then appeared about three billion years before multicellular organisms
Early photosynthetic bacteria
Earliest prokaryotes were subject to harsh anaerobic environment
Reducing atmospheric conditions and intense solar irradiation
Many species of bacteria still thrive under the hot and salty conditions
Characterized early living conditions on Earth
Evolution of photosynthesis to trap light energy was important
First evolve bacteria capable of anoxygenic photosynthesis
Once earth's surface cooled, molecular oxygen appeared due to development of oxygenic
photosynthesis
Process appeared first in bacteria (cyanobacteria) about 2.5 billion years ago
Oxygen created as by product of carbon dioxide conversion to sugar
Abundance of oxygen permitted evolution of cellular metabolic pathways for living
organisms
Two major evolutionary lineages: Bacteria and Archaea
Microorganisms don’t leave fossil record, because cannot calcify as like bones
Bones infected by bacteria
Osteomyelitis, detected in 200 million year old skeleton from Permian period
Earliest evidence of bacterial diseases
Comparison of nucleic acid sequences revolutionized perception around cellular life
evolution on Earth
Phylogenetic tree shows three major branches or domains of cellular life
oProkaryotes comprise two of these major branches
Bacteria
Archaea
oOther lineage includes all eukaryotes
Eukarya
Three domains referred as super kingdoms
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
True nucleus is absent in a prokaryote. Ancient single-celled organisms with fossil record back 3. 6 billion years. Length of time allowed to evolve high diversity. Able to survive in wide range of environments. Prokaryotes were the first cellular life on earth. Earliest microscopic cellular life resembled modern bacteria. Continued to evolved for 2 billion years. Eukaryotes then appeared about three billion years before multicellular organisms. Earliest prokaryotes were subject to harsh anaerobic environment. Reducing atmospheric conditions and intense solar irradiation. Many species of bacteria still thrive under the hot and salty conditions. Evolution of photosynthesis to trap light energy was important. First evolve bacteria capable of anoxygenic photosynthesis. Once earth"s surface cooled, molecular oxygen appeared due to development of oxygenic photosynthesis. Process appeared first in bacteria (cyanobacteria) about 2. 5 billion years ago. Oxygen created as by product of carbon dioxide conversion to sugar. Abundance of oxygen permitted evolution of cellular metabolic pathways for living organisms.
