lecture 11 Flashcards
following anaerobes were _______ with
- photoautotrophs
- oxygenic photosynthesis
the key innovation made by photoautorophs was
The advantage of this was
- use of H20 as the electron donor (oxygenic photosynthesis)
- water was very plentiful
called oxygen photosynthesis because
oxygen was a by-product of this new synthesis
stromatolites formed by
photosynthetic bacteria grows in mound that are everntually covered by debris
- as the bacteria get covered they die while new bacteria gorw on top of the debris
- occurs again and again produceding fossilized layered rock able to preserve
number of backteria in shark bay
3 billion cyanobacteri/m^2 of mat
stromatolites reach what height
1.5 meters high, up to ~10m
modern stromatolites generally found where
in hot or hyper-saline environments where they are free from grazing and burrowing animlas
cyanobaceria are the likely the first life form to _____
But they are not likely the first ______
produce hard parts that can crystlalize
life forms
once oxygen photosynthesis started with advent of cyanobacteria _______
this resulted in ________
____________ precipatated to the sediments leaving banded iron formations
by 2 billion years ago, the ferrous iron within the oceans had largely __________
- O2 accumulated in the atmosphere and waters of the ancient seas
- the oxidation of ferrous iron to ferric iron in these surface waters
- ferric iron with O2 attached,
- precipitated to the ocean floors
Evarly biodiversity on earth consisted of ______
prokaryotes
cyanobacteria has occupied the earth for ______
and was the _____ life form for more than _______
at least 3.5 billion years
dominant
-1.5 billion years
build up in O2 in the atmosphere had three significant affects
- A rapid expansion in the diversity of aerobic microorganisms, with a concurrent reduction in anaerobic prokaryotes
- The first ice age (known as a snowball earth)
- providing the atmosphere needed for the next major evolutionary step… origin of eukaryotes
The great oxygenation event
- 2 BYA, major extinction event (not in the 5
- when the iron on earth had absorbed much of the O2, it could hold the remainder remained in the atmosphere
- free oxygen toxic to anaerobes and wiped a lot of them out
free oxygen reacted with ______
Causing it to ______
And trigger ______
And so anaerobic organisms ______
- atmospheric methane( a greehouse gas)
- greatly reduce in concentration
- a glaciation possibly the longest snowball Earth episode in the Earth’s history
- began to evolve, taking advantage of the newly available O2
archae and bacteria developed from
archaea have genes similar to
Eukaryote branched from
- a common ancestor
- both bacteria and eukaryotes
- archaens millions of years ago
evolution of eukaryotic life is based on
endosymbiosis
endosymbiosis
one species(the endosymbiont) living within another species(the host)
development of organelles known to be from
the plasma membrane
heterotrophic cells acquired chlorplasts by ____
and mitchondria by ______
whereas normally the engulfed cell would _______
- incorporating cyanobacteria as the endosymbiont,
- other symbionts
- be digested
Soft organisms are not associated with ________
So it would be very unlikely for them to ______
sediment/rock
be preserved
currently oceans have low levels of ________
due to it being locked up in ________
- iron in solution
- sediments following oxidation
There is currently ____x more oxygen stored in _____
than is present in the _________ as a result of _____
- 20
- BIFS
- atmosphere
- billions of year of oxygen production by photosynthesis
The principle source of iron in steel production is
The iron locked up in bifs
addition of the energy source of the cell(__________)
are thought to have occurred via
- mitochrondria and chloroplasts
- failed phagocytosis
Host cell for cyanobacteria and mitochondria provide
Nitrogen and Phosphorus, and shelter(membrane)
cyanobacterium and mitochondria provide
energy for the cell
obligate mutualistic relationship
two organisms becoming one
Evidence for endosymbiosys theory(2)
- Eukaryotic chloroplasts has cyanobacterial properties
- actual cyanobacteria occurs within the cells of many organisms today
cyanobacterial properties of eukaryotic chloroplasts (3)
- remnant dna in chloroplast are similar to cyanobacterial DNA in that its circular and and lacking histones
- ribosomes in chloroplast as similar to cyanobacterial ribosomes in that they’re small(unlike the larger type found in eukaryotes)
- nucleotide sequences of DNA and ribosomal RNA are similar between chloroplasts and Cyanobacteria
Histones
proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes
Theory of secondary endosymbiosis - _______
explains how _______
these ideas are __________
- eukaryote engulfing another eukaryote
- other algae obtained chloroplasts
- more complex, often unresolved
Evidence for theory of secondary endosymbiosis
- more than two envelopes around the chloroplasts of some algae
- small nuclei and eukaryotic sized ribsomes outside two inner chloroplast envelopes but inside chloroplast
The rise of eukaryotic multicellular organisms and larger eukaryotes directly linked to _______
- this is due to ________
- large cells have a significantly harder time _______
larger cells need a higher level of ________
- rise in O2 levels
- the effect of size on surface to volume ratios and O2 ability to diffuse into aerobic cells
- diffusing O2 into their center than harder cells
- O2 to develop and thrive
Theories for multicellular evolution
cells found eachother and aggregated to form colonies
- cells remained attached after cell division
Advantages of being multicellular
- increase protection form the environment(less surface area exposed)
- division of labour(due to specialization)
Disadvantages to being multicellular
The larger you get the more you must specialize(most of your cells can communicate with environment)
