Origin Of Life & Symbiosis (9) Flashcards
Life requirements? (2)
• Metabolism.
• Reproduction.
Scenario of Earth 3.5 billion years ago? (2)
• No O2.
• High temperatures.
Who lives there in such an area 3.5 mya? (3)
• Prokaryotes/Bacteria.
• Archaebactria.
• Eukaryotes.
Prokaryotes/Bacteria attributes? (2)
• Rapid reproduction.
• Reproduction through binary fission.
How did bacteria reproduce?
Binary fission.
Which SC are bacteria associated with?
Biological SC.
Archaebactria?
= prokaryotic extremophiles.
Extremophiles?
= organisms that prefer/love living in extreme environments.
Eukaryotes?
= organisms that can be seen with the naked eye & are the most complex in structure.
Unicellular eukaryotes?
= have high genetic diversity.
How did Eukaryotes evolve from prokaryotes?
Discovered through Loki’s castle where Lokiarchaeota makes Archae paraphyletic & therefore eukaryotes related to Archae (prokaryotes). Therefore, prokaryotes gave rise to eukaryotes.
Similarity between Gram+ & Gram-?
• Cytoplasmic membrane.
Gram- bacteria attributes? (3)
• Outer membrane.
• Lacks teichoic acid.
• Porine enable permeability.
Gram+ bacteria attributes? (2)
• Multiple peptidoglycan layers.
• No porins.
Mid-Atlantic Ridge?
= northernmost field of hydrothermal vents.
Loki’s castle attributes? (5)
• Rich in mineral deposits.
• Habitat for Archaea (Angler fish).
• Give us a clue on origin of Archaea.
• Named after norse god, Loki.
• Lokiarchaeota.
Why is it a “castle”?
It’s because it has 5 active black smokers chimneys on large flat tops.
Why was Loki’s castle called Loki’s castle? (2)
• Difficult to find.
• Master of disguise.
Results of Lokiarchaeota? (2)
• Makes Archae paraphyletic (from monophyletic).
• Transition from 3 domain system to 2 domain system.
Life driving forces? (2)
• Food.
• Reproduction.
Why are the life driving forces in their specific order?
The need for energy through food drives endosymbiosis.
Food?
= organic compounds that are spontaneously made/slow.
Who consumes food?
Heterotrophs.
Result of limited food?
High competition.
Solution to limited food?
Make your own food!
Why did autotrophs exist?
To prevent experiencing food limitations (high competition).
Always think about what scenario?
Anaerobic environment.
Autotrophic types? (2)
• Chemoautotrophs.
• Photoautotrophs.
Chemoautotrophs?
= make own food using reducing energy from chemicals.
Eg of Chemoautotrophs?
Sulphur-bacteria.
What problem did Chemoautotrophs experience?
Resource limitation.
Solution to the problem of Chemoautotrophs?
Used H20 to reduce O2.
Photoautotrophs?
= cyanobacteria.
Cyanobacteria attributes? (3)
• Blue-green algae.
• Have chlorophyll to enable light capture.
• H2O is abundant but build up of O2.
What “problem” did Photoautotrophs experience?
H2O abundance but build up of O2.
What did Photoautotrophs use to produce O2?
H20.
Result of Photoautotrophs dominating landscapes?
They were able to make their own food well & therefore be able to reproduce.
Elaborate reasons to why O2 is not good? (2)
• It is a precursor of O3 and contains free radicals with high reactivity. This causes O2 to be toxic in anaerobic environments & therefore decreases the energy source of food with decreasing UV.
• At the time organisms were living in an anaerobic environment.
What do you do when autotrophs are breaking down your food as a heterotroph/aerobic prokaryotes?
Adapt.
Therefore, adapting produces? (2)
• High efficiency.
• High anaerobic respiration.
Eg of aerobic prokaryote that adapted?
Alpha-proteobacteria.
How did alpha-proteobacteria deal with the high O2 levels? (2)
• Used the oxidative power of O2 for complete food breakdown & maximum energy release.
• O2 as a final electron acceptor to produce water.
3 domain system in Phylogenetic tree?
Bacteria Archae Eukarya.
How did early eukaryotes do to survive the high O2 levels?
They ate Alpha-proteobacterium (aerobic).
Why did early eukaryotes eat these?
Because alpha-proteobacteria offered relief from the anaerobic environment.
In order to continue feeling relieved, what did the early eukaryotes do?
They did not digest the alpha-proteobacteria but held them hostage to receive permanent relief & to keep prokaryotes producing food for them.
What did this need for permanent relief lead to?
In a permanent relationship between the eukaryotes & the alpha-proteobacteria.
What did this permanent relationship ultimately lead to?
The development/evolution of mitochondria.
What organisms then evolved from the development of mitochondria?
Mitochondriate eukaryotes.
Mitochondriate eukaryote?
= true eukaryotes with mitochondria which are still heterotrophic.
Are all true eukaryotes mitochondriate?
No, some were amitochondriate eukaryotes (protoeukaryote-like) which still had mitochondrial genes & mitochondrial remnants due to all of them being originally mitochondriate.
Survivors of ME? (3)
• Aerobic eukaryotes LECA (Hydrogenosome mitosomes).
• Lokiarcheota.
• Aerobic alpha-proteobacteria.
Non-survivors of ME? (3)
• Archae.
• Eukarya.
• Other bacteria.
Evidence of bacterial endosymbiosis? (3)
• Membranes.
• DNA.
• Reproduction.
Membranes attributes? (2)
• Indicate the type of endosymbiosis you had.
• Count number of membranes to know whether it’s Primary, Secondary or Tertiary endosymbiosis.
DNA attribute/tip?
Observe how many DNAs it has.
What about chloroplasts?
Since you had heterotrophic eukaryotes with mitochondria they still had a challenge of food limits.
How did they solve the food limits?
Make own food via photosynthesis.
How could these heterotrophic eukaryotes “make their own food” via photosynthesis?
By eating/phagocytocizing Cyanobacteria.
Why did the heterotrophic eukaryotes eat cyanobacteria?
Because of the driving force of limited food.
Why were cyanos held hostage by mitochondriate eukaryotes?
Held hostage for permanent food supply.
Result of this permanent relationship through permanent food supply?
Evolution of the 1st plastid/chloroplast.
How/through what did the 1st plastid evolve?
Via co-evolution with the mitochondriate eukaryotes.
What new organisms did they become when they ate Cyanobacteria?
Aerobic autotrophic eukaryotes.
2 potential autotrophic food sources?
• Cyanobacteria (via primary endosymbiosis).
• 1st eukaryotic autotrophs (via secondary endosymbiosis).
Mitochondrial acquisition attributes? (2)
• Ancient.
• Occurred once.
Plastid acquisition attributes? (2)
• Very recent.
• Occurred more than once.
Primary endosymbiosis process? (5)
Eukaryotic heterotroph eats Photosynthetic endosymbiont
|
Eater has food vacuole of eaten.
|
Vacuole membrane of eaten disappears.
|
Eater becomes a eukaryotic autotroph.
|
2 membranes.
Secondary endosymbiosis process? (3)
Bigger eukaryotic autotroph eats smaller eukaryotic autotroph.
|
Eater digests everything of eaten except chloroplast.
|
>=3 membranes around chloroplast.
Dinoflagellates are an eg of what type of endosymbiosis?
Tertiary endosymbiosis.
How are Dinoflagellates that kind of endosymbiosis?
By replacing its ancient plastid of red algae origin with another algae, which also contains a plastid of red algae origin.
What did Dinoflagellates take on/phagocytocise?
Red algae.
Kinds of aerobic eukaryotes eaters? (2)
• Fussy eaters/ inefficient digesters.
• General eaters/ efficient digesters.
Fussy eaters attributes? (2)
• Strong drive to take on/eat endosymbionts.
• Co-evolution more likely to occur.
General eaters attribute?
Could look for alternative food sources.
What do these types of aerobic eukaryotes result in? (2)
A radiation of eukaryotes where:
• Some + Photosynthetic endosymbionts.
• Some colourless + non-photosynthetic.
Lateral/Horizontal evolution?
= mixture (not a blending) of more than 2 organisms where reticulation events lead to chimaeras (mixes of 2 separate lineages).
Lateral evolution attributes? (2)
• Permanent endosymbiosis where you have mt & cp.
• Inside eukaryotic host cell.
Original grand theft?
= huge leaps in “evolution”.
Chimaeras problems? (4)
• Different timing of cell division.
• Differences in sexual reproduction (conjugate vs gametes).
• Each with selfish needs.
• Development from hunter-prey lifestyle to commensalism lifestyle.
Eg of chimaera?
Hatena arenicola.
How does the host ensure its survival? (2)
• Host must make endosymbiont captive.
• Host must control endosymbiont.
Ways that the host makes the endosymbiont captive? (2)
• By synchronizing division.
• By passing it on to the next generation.
How must the host control the endosymbiont?
By stealing the endosymbiont’s vital genes (lateral transfer to host nucleus).
Evidence of lateral transfer to host nucleus?
Gene sequencing.
How is endosymbiont reliance seen? (3)
• DNA of endosymbiont in host nucleus.
• Protein of endosymbiont made in host cytoplasm.
• Must cross at least 2 membranes.
Sexual reproduction challenge for endosymbiont in primary endosymbiosis?
Eaten by prokaryotes and has to deal with conjugation.
Sexual reproduction challenge for endosymbiont in 2ndary & Tertiary endosymbiosis?
Eaten by eukaryote & has to deal with syngamy & gametes.
Sexual reproduction challenge for host in endosymbiosis?
Host must retain but accommodate endosymbiont.
Types of gamy/reproduction? (3)
• Isogamy.
• Anisogamy.
• Oogamy.
Isogamy attributes? (2)
• Both gametes swim.
• Same size.
Anisogamy attributes? (2)
• Egg & Sperm different size.
• Both gametes swim.
Oogamy attributes? (2)
• Egg & Sperm different size.
• Egg can’t swim, Sperm can swim.
How are endosymbionts passed on in Isogamy?
Both partners contribute their organelles.
How are endosymbionts passed on in Anisogamy?
Only female contributes because of big gamete size.
How are endosymbionts passed on in Oogamy?
Only female contributes organelles.
Eg of an exception of how endosymbionts are passed on?
Yellow wood trees.
Heterotroph?
= organism that obtains energy by feeding on other organisms.
Autotroph?
= organism that makes its own food from inorganic substances/ from the environment.
Chemotroph?
= organism that makes their own food using reducing energy from chemicals.
Eukaryote?
= organism that has cells with a complex internal structure.
Prokaryote?
= single-celled organism that lacks membrane-bound organelles with its DNA free in the cytoplasm.
Endosymbiosis?
= mutually beneficial relationship where one organism lives within another organism.
Aerobic?
= with O2.
Anaerobic?
= without O2.
Cyanobacterium?
= photosynthetic bacteria that contain chlorophyll & release O2 during photosynthesis.
Mitochondria?
= powerhouses of the cell.
H2 hypothesis?
= states that a H2-producing aerobic bacteria & a H2-consuming anaerobic Archae grew along each other until the Archae engulfed the bacteria.
Result of high levels of O2?
Posed a problem as they were in an anaerobic environment.
Why is O2 not good? (2)
• Precursor of O3.
• Toxic in an anaerobic environment.
What did the alpha-proteobacteria produce? (2)
• CO2.
• H2O.
Refugia?
= space that remains the same & enables lineages to survive extinction events.
Term used to describe the amitochondriate eukaryotes?
Hydrogenosomes.
Hydrogen hypothesis attributes? (4)
• Bacterial cell used H2 as a form of reduction energy to make it’s own food.
• Facultative endosymbiont’s anaerobic metabolism (H2 waste).
• Anaerobic host uses H2 (chemoautotroph).
• Hydrogenosome first, then mitochondria.
Hydrogen hypothesis?
= states that mitochondria acquisition is not driven by O2.
Syntrophy?
= eating together.
Similarity/Thing to note about Red & Green algae?
Both are Gram- bacteria.
Plastidial endosymbiosis attributes? (2)
• Common & distributed across tree of life.
• Not always independently, but could be eaten again & again.
Protist groups arising from red algae? (3)
• Dinoflagellates.
• Apicomplexans.
• Stramenopiles.
Protist groups arising from green algae? (2)
• Euglenids.
• Chlorarachniophytes.
Egs of SA’s dinoflagellates? (3)
• Durinskia capensis.
• Amphidinium latum.
• Rhodomonas.
What did Durinskia capensis eat?
Red algae.
What did Amphidinium latum eat? (2)
• Brown algae.
• Green algae.
What did Rhodomonas eat?
Red algae.
Result of chimeraes?
Enables Original grand theft.
What drove lateral evolution?
Food limitation (selection pressure).
Endosymbiont?
= microbial cell that lives inside a microbial host.
Endosymbiont attributes? (3)
• Cyanobacteria were inside heterotrophic eukaryote.
• Red/Green algae were inside heterotrophic eukaryote.
• Endosymbiont relationship gives rise to plastids.
Eg of an endosymbiont?
Durinskia capensis in SA.
Plastid?
= double membrane organelles inside plants/algae.
Egs of plastids? (3)
• Chloroplasts.
• Chromoplasts.
• Leucoplasts.
List of the primary plastids? (2)
• Red algae.
• Green algae.
What happened to the red & green algae?
They were genetically integrated with the host cells & gave rise to a variety of protist groups.
Hatena arenicola attributes? (2)
• Heterotrophic flagellate.
• Eats Nephroselmis.
Why is the size of gametes important?
It’s because it determines how the endosymbiont is transferred to future generations.
Types of DNA? (2)
• Mitochondrial DNA.
• Chloroplastic DNA.
Which side of the family do mt DNA & cp DNA come from?
Maternal side of the family.
Through which family are mt DNA & cp DNA passed on to the next generation?
Via the maternal side of the family.
Why are mt DNA & cp DNA passed on via the maternal side of the family?
It’s because there’s more space in female gametes.
What’s the benefit of us knowing about how endosymbionts are transferred in subsequent generations?
It gives us an idea of plastid evolution & diversification across groups.
What was the implication of plastid evolution & diversification across groups?
The transferring of species from the prokaryotic world to the eukaryotic world has caused a significant increase in global productivity.
