BIOL 1010 Lecture Notes - Lecture 20: Monera, Membrane Lipids, Peptidoglycan
Major Lineages of Life
December 2, 2014
The Ocean today is: 99% microbes and 1% aquatic animals
The living world has been separated into 2 kingdoms: Animals and Plants since the ancient
times.
In 1970, the five kingdom scheme was created:
• Protista
• Monera
• Animalia
• Plantae
• Fungi
Some Problems with this scheme:
• Imperfect fit to phylogeny (protista and monera are paraphyletic groups)
• No formal taxon for Eukaryotes
Three Domain Scheme
• Bacteria
• Archae
• Eukarya
Importance of Prokaryotic Life:
• On Earth for >3 billion years
• Far more metabolic diversity than eukaryotes
• Responsible for most biological activity in many ecosystems
• More prokaryotes than human cells in the body
• Causes many major diseases and infections
• Biotechnology
Typical Prokaryotes:
• Small, simple cells with small genomes
• Consequently, very efficient
o growth when resources are scarce
o very rapid reproduction (by binary fission) when resources are plentiful
1. Bacteria
• most diverse domain
• most of the well-known prokaryotes
• includes all known disease-causing prokaryotes
• CELL SURFACE:
o Usually 2 bounding membranes (plasma and outer)
o Peptidoglycan layer between complex polymer of sugars and
amino acids
o Some may only have a plasma membrane with a thick
peptidoglycan wall
• Important types of Bacteria:
o Spirochetes
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