So I've combined the answers from destroyer and achiever..does this seem right:

small, inorganic molecules > atmospheric gases (H2, CH4, H2O, NH3, H2S) > small organic molecules (nucleic acids, proteins) > packaging of molecules into protobionts > prokaryotes > eukaryotes > etc.

is that chronologically correct?

You should include whether the first cells were heterotrophs or autotrophs also.

for the record, the first were anaerobic heterotrophs

for the record, the first were anaerobic heterotrophs



are you sure? can someone confirm?

are you sure? can someone confirm?

I confirm.

They were anaerobic because early earth atmosphere had no O2 and they were heterotrophs because we still didn't have an ozone layer to block out the extremely harmful UV light.

I confirm.

They were anaerobic because early earth atmosphere had no O2 and they were heterotrophs because we still didn't have an ozone layer to block out the extremely harmful UV light.

but they were prokaryotes, right? thanks for the explan. referring to protobionts. i have found that they are either prokaryotes... or either what came right before the prok.? what would it be on test day?

i cant remember exactly which question it was but protobionts are def. the step right before prokaryotes.

But they are not a prokaryote yet, right? just making sure....

but they were prokaryotes, right? thanks for the explan. referring to protobionts. i have found that they are either prokaryotes... or either what came right before the prok.? what would it be on test day?


There was no 'life' on early earth. Just a bunch of simple reducing molceules like H2S, CH4, H2O vapor, and NH3.

The extremely harsh conditions of the sun and it's UV rays are infact what favored the development of simple organic molecules in very early earth. This was proven by the Miller-Urey experiement. Then the endosymbotic theory explains that some of these simple molecules that joined together began to become advanced molecules and they would ingest other simple molecules in order to help them better adapt to their cuurent environment.

This would explain why chloroplast and mitochondria have their own proteins and DNA. Then these advanced molecular forms began developing an enternal environment much different than the external environment, which were separated by a type of membrane. These are what are known as protobionts. Protobionts are neither prokaryotes nor eukaryotes.....they are simply protobionts.

After that prokaryotes developed and then eukaryotes.

:)

I thought Miller-Urey used an electrical charge + simple reducing atmosphere to produce more complex molecules? Simple electrical charge = lightning.. not light from the sun?

and the endosymbiotic theory was an explanation for how mitochondria and chloroplasts made their way into eukaryotes.. or at that time.. other prokaryotes.. Does endosymbiotic theory also explain how small molecules aggregated to bigger molecules? symbiosis is a relationship between two living things.... these small molecules weren't living...?

I thought Miller-Urey used an electrical charge + simple reducing atmosphere to produce more complex molecules? Simple electrical charge = lightning.. not light from the sun?

and the endosymbiotic theory was an explanation for how mitochondria and chloroplasts made their way into eukaryotes.. or at that time.. other prokaryotes.. Does endosymbiotic theory also explain how small molecules aggregated to bigger molecules? symbiosis is a relationship between two living things.... these small molecules weren't living...?


I do apologize. Thanks for catching my screw up, Contach.

The high amounts of UV hitting the earth was due to the lack of an ozone layer which in turn was due to the lack of oxygen. The lack of OXYGEN is what supported early life on earth. Because it is believed that the presence of oxygen would not have made it possible for these organic molecules to develop. Which is further supported by the fact that early life was anaerobic heterotrophs.

Due to the fact that there was no ozone and there was high energy hitting the surface of the earth including the surface of the oceans, that means there was lots of H2O vapor in the atmosphere. Couple that with the instability of the atmosphere at that time and you get massive thunderstorms.

The lightning would strike the rocks near the shore of the ocean where inorganic molecules were deposited and it would form some sort of reaction (as evidenced by the Miller Urey experiment) that would join these molecules and make them organic molecules.

The endosymbiotic theory DOES mainly concern chloroplast and mitochondria (yes they are living, note how I put living in between quote sin my previous post) but my Bio teacher also said it can be used to explain other simpler molecules....so someone correct me if I am wrong on that.

i thought the term endosymbiontic implied that it was about how mitochondria and chloroplasts became endosymbionts. Maybe.

i thought the term endosymbiontic implied that it was about how mitochondria and chloroplasts became endosymbionts. Maybe.


I'm fairly certain that endosymbiotic in its most basic form means "big guy ate the little guy" and this is obviously how chloroplast and mitochondria came about, since they are the most widely used example.

But are they the only two examples? I recall my teacher saying that many molecules engulfed one another before they became collectively know as mitochondria or chloroplast.

i dont think it would be testd on dat... they dont test exceptions....
and that seems like one of those... it probably happened... but sure...
i looked it up adn all the endosymbiont theories on ly discuss mit. and chl.

but if i see it on the test, and you mentioned it, ill be sure ot come back and thank you!

plus i think the point of hte endosymbiont theory is that mitochondria nad chloroplasts used to be free living (like you said) made own DNA and such.

what other symbionts of the cell do that?

i dont think it would be testd on dat... they dont test exceptions....
and that seems like one of those... it probably happened... but sure...
i looked it up adn all the endosymbiont theories on ly discuss mit. and chl.

but if i see it on the test, and you mentioned it, ill be sure ot come back and thank you!

plus i think the point of hte endosymbiont theory is that mitochondria nad chloroplasts used to be free living (like you said) made own DNA and such.

what other symbionts of the cell do that?

Yeah, like you said, I doubt they test on specifics like that.

But what I am saying is that MANY little teeny tiny organisms engulfed one another before they became known as either mitochondria or chloroplast...

I'm basing this off of what my teacher told me, and he could be wrong, but it makes sense to me.

who knows... its like discussing dinosaurs and how we know waht sounds they made. ha... one reason i hate the old bio stuff

The high amounts of UV hitting the earth was due to the lack of an ozone layer which in turn was due to the lack of oxygen. The lack of OXYGEN is what supported early life on earth. Because it is believed that the presence of oxygen would not have made it possible for these organic molecules to develop. Which is further supported by the fact that early life was anaerobic heterotrophs.

Due to the fact that there was no ozone and there was high energy hitting the surface of the earth including the surface of the oceans, that means there was lots of H2O vapor in the atmosphere. Couple that with the instability of the atmosphere at that time and you get massive thunderstorms.

The lightning would strike the rocks near the shore of the ocean where inorganic molecules were deposited and it would form some sort of reaction (as evidenced by the Miller Urey experiment) that would join these molecules and make them organic molecules.



sweet, that explains a lot!
thanks