Lecture 5 Outline
That many bugs live where?
Pink Filaments from hot spring
Another hot spring cyanobacterial mat
Yet another hot spring cyanobacterial mat
Anabaena, a nitrogen-fixing cyanobacteria
A black smoker, hydrothermal vent
Thermus aquaticus, the mother of polymerase chain reaction (PCR)
Yet another thermophilic bacteria
Endolithic cyanobacteria, living within a rock
Arthrobacter, a common soil microbe
Chorobium, an anaerobic photosynthesizer
Phylogeny - how organisms are grouped
Traditional (old-fashioned) comparisons between organisms based on morphology, biochemistry, etc
Modern phylogeny uses variations in rRNA
Microbes are isolated, their rRNA purified, then the rRNA sequence is determined
rRNA sequences are feed into complex mathematical systems and similarities and differences are given numerical values
Relatedness trees can be created
The Tree of Life
Three major kingdoms
Bacteria - prokaryotes
Eucarya - protists, fungi, animals, plants
Archaea - prokaryotes, generally the "weird" bugs
Organisms more related to ancient life forms are closer to the bottom of the tree
Distances between organisms on the tree indicate relatedness
Often times the more primitive organisms are anaerobic since early life lived in a reducing oxygen-free environment
The rise of oxygen-producing photosynthesis caused a mass extinction of early anaerobic life forms, although some still survive today
Endosymbiont Theory
An early eukaryote, probably like an Archaebacterium, ate (phagocytized) a bacteria
This bacteria could do something (a metabolism) useful to the Archaebacterium
So, the Archaebacterium (host) did not degrade the bacteria inside itself
They lived together in harmony
An aerobic bacteria led to the mitochondria of today
A photosynthetic bacteria (like a cyanobacteria) became the modern chloroplast
How do they know this happened?
The mitochondrial and chloroplastic DNA tells us that these are related to bacteria not archaea
Phagocytosis would cover the incoming bacteria with a second membrane and mitochondria and chloroplasts generally have two membranes (not one like a bacteria)
How diverse is microbial life?
Humans are mesos - everything is in the middle
It is hard to imagine the very large or very small
Our eyes see only a small fraction of the electromagnetic spectrum
We live in middle-of-the-road (or so it seems) conditions
About 25 C, pH 6-8, 1 atmosphere pressure, etc
Most microbes are also mesophiles - living in the middle range
But some microbes live at the extremes of temperature, pH, salinity, and pressure
Many graphics shown
Loose discussion of Yellowstone hot/acid springs
Continuing with ocean hydrothermal vents - smokers
What good is all this diversity to us?
Diverse organisms house diverse functions, diverse metabolisms, diverse enzymes
More functions, more products, more money - the bottom line
But we are losing diversity through man's actions
Destroying the rain forest causes extinctions of microbes that may be useful to us
Cures to diseases could be lost, new enzymes are lost, potential profit is lost
