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Lecture 3

Biological Sciences
Course Code
Herbert Kronzucker

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Lecture 3
September 22 2008
How do you study for this course to do well? I am not giving summaries to you like in previous
lectures. This is a 3rd year course so you don’t get that benefit. I used to do this so you could
refine your notetaking skills. There are many examples/numbers/technical terms and pieces of
information in general and nobody can write all those down. How do you distinguish what you
should remember? If I mention something only once chances are you will never be asked about
Important points come up repeatedly in a lecture for me to expect you to know them
actively. If you don’t hear something twice or more then you don’t have to know them
There are short essay questions in which you can put your answer together in different ways.
You can have 2 answers depending on the relevant information you include in your answer. It
must be relevant and correct to get marks. Usually the marks come in pairs. The important
pieces of information will be repeated again and again. We will build pieces of information and
you will have an easier time to answer on the exam. There are a few ‘active questions where I
may ask for a specific number or technical term.
Many members consider themselves tough in the hip-hop community (Puff Daddy Picture). This
guy wouldn’t do well in any of the previous environments that we talked about. This mud
puddle has a pH of 1.9! You heard about a guy who got stuck in a crevice and he had to cut off
his own arm to escape? Most animals/plants/microbes and other members of the biological
kingdom would have a problem surviving in these places (on overhead). There are some
bacteria and algae that survive in this lake (refer to last week). There are some water vapours
that you can put in outer space and they will survive for an amount of time. Toughness of life is
astonishing and humans have nothing up against some of these organisms.
Buried Alive by Edgar Allen Poe he wrote many things about being buried alive. I told you
about bacteria that can live in solid rock 3 ½ Kms in. They might be dividing 1 time in 100
years and their metabolism would be very low but they won’t die. We must be very careful that
when we travel to a place like Mars that we don’t have organisms on the equipment. They could
be buried and once the rubber rots away and decays in the atmosphere of Mars they might come
crawling out and start a new history of life on the planet.
Summary Hillary Clint said “it takes a village to raise a child” and I would like to use this for
community ecology. We have the gage claims about life on Mars etc. In ecology it means it
takes a community of organisms with adaptations to raise children with extreme adaptations. To
produce life forms that can survive the boiling temperatures of the geysers in Yellowstone Park.
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Let’s gage these organisms against the gage of evolution. I won’t go into religious views at this
Earth is approximately 4.6 billion years old and all the evidence we have about its origin
supports this date.
The universe is 11.5 billion up to 14 billion years old.
About 1/3 of the time earth has been around as a planet. In the early days of the life of the planet
but not of organisms things were tough. This is the Hadean eon. Remember how to break down
the periods of time in geologic history? One term is eon (s) and another term is era (s). We also
refer to periods. Know these 3 terms. In the Hadean period we have 4.6 to 3.8 billion years
ago and it was a harsh time on planet earth. Meteorite fluxes, gamma rays and it was bombarded
with matter that kept hitting it. The entire solar system was very young and the planets and
moons were just forming. There was a lot of ‘traffic of matter in our solar system. We have
documentation of the early days on earth, the 1st 1.2 billion years ago. There are wounds and
damage on what was the surface.
S: Where did the gamma rays come from?
P: The sun was hotter and more powerful and that is where they came from.
There was little atmosphere protecting the earth at this time. It would have been impossible for
the extremeophiles to exist on the planet and everyone agrees with that.
Next was the Achean period. This is reverse to archae which is the name of the bacteria that is
from the extremeophiles that we talked about. The names are just coincidence. We don’t know
what the earliest days were but there is a time window (signified by the arrow – on overhead).
The Proterozoic period is where life began on the planet. We don’t know where they began but
the professor from Germany believed it was in the ocean vents (in the black smokers). Most
biologists think it was not in the ocean but on the surface of the earth. We are not really sure
about the timeline. 3.8 billion to about 2 ½ billion we think is the window of life. The textbook
evidence for the earliest fossils came from Australia. They were supposed to be fossils of
cyanobacteria type formations but this has been debunked successfully (by Dr. Brazier from
Oxford). Everyone wants to know the oldest fossils of life on earth. Discoveries were made in
Greenland and Africa as well that were in that bracket (3.8 billion maybe) but none we can say
for sure are fossils that represented life. The branching patterns couldn’t have been the footprints
of the early forms of life but explained by intrusions of lava flows into rocks at that time.
We know for sure that at 2 ½ billion years when proterozoic time occurred life began to
expand at a high rate. This is when photosynthesis can be documented on the planet as
well (troposphere). So photosynthesis might have evolved very quickly. The first life forms
were chemosynthetic and they are in the world’s trenches. This is where oxygen begins to rise,
prior and before we only had trace amounts of O2 on earth. All experts agree that the splitting of
the molecule was invented by using oxygen. Then you use electrons and energy out of the water
splitting to fix CO2 which was on the planet from the early days. It is also on Mars and Venus.
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95% 98% of the troposphere are CO2. On earth it is 78% nitrogen, 21% oxygen, 0.036% CO2.
So it was gobbled up almost completely by carbon fixation while enriching it with oxygen. A
complete revamping by life.
From 2 ½ billion year timeline we have fossils and they are true evidence of life. We know for
sure. They can be found along the N. Shore of Lake Superior (Gunflint Churt Fossils). We are
famous for fossils. The other fossils are from the big explosion of life in the onset of the
Phanerozoic period. This is the modern age of life. It began when the pre-history was over and
the first period of relevance was the Cambrian. The big riddle that Darwin tried to come to
grips with. How did we get such a multi-cellular type of life? We time it at about 570 million
years ago. We begin to see stars for the first time, causations, arthropods, etc. Remember 70% of
the species alive today (100 million) 70% of them are believed to be insects.
We also know there were other communities that predate the change to the Cambrian by about
100 million years. These fossils are called the Ediacarans. These are in Australia preceding the
explosion of the Phanerozoic and in the Proterozoic eon. We thought it was unicellular life but
these Ediacaran fossils are teaching us otherwise. The Ediacaran communities are fascinating
because the organisms were peaceful. It evolved before predation and nothing ate anything else.
They were like ferns floating in the ocean. They consumes by diffusions and osmosis that came
in a natural way. The Ediacaran was a peaceful time.
Today at time 0 (zero) despite all this history or because of it we have a larger diversity than we
have ever had at any point throughout the history of life.
S: What were they fossils of? Plants or animals?
P: Both animal and plant cells made the organisms of the multi-cellular Ediacaran. We are
looking at ‘footprints’ in rock sediments so nobody knows for sure. If the rock substrates were
the right material we got footprints that lasted hundreds of millions of years. Newfound and
Africa also have the Ediacaran fossils. I recommend for everyone to go to Newfoundland and
see these fossils from 630 million years ago. These things will change your lives! Go to
Yellowstone National Park and see the geysers and ask how these organisms survive. How is
their areplication different than ours? Ask yourself these questions. It is a good way to approach
living. Go to see the others from the Cambrian explosion that is 535 million years old roughly.
Burgess shale’s of the Rocky Mountains in Yoho national park is the richest evidence of the
explosion in the Cambrian. These are world heritage sites.
This slide is to show the Euarchaeota and the Crenarchaeota. The basics are very important:
Original cell to bacteria to Eukarya (cell line which we are a part of) Euarchaeota  
Halobacteriales live in salt.
Methanogenales in the black smokers
BGYC61H3F.September.22.2008 Lecture 3 3
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