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Flashcards in lecture 11 Deck (36):

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 ______



cyanobacteria has occupied the earth for ______
and was the _____ life form for more than _______

at least 3.5 billion years
-1.5 billion years


build up in O2 in the atmosphere had three significant affects

1. A rapid expansion in the diversity of aerobic microorganisms, with a concurrent reduction in anaerobic prokaryotes
2. The first ice age (known as a snowball earth)
3. providing the atmosphere needed for the next major evolutionary step... origin of eukaryotes


The great oxygenation event

2.2 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




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 ______

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 _____

- 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



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)