Skip to main content

Why are chemosynthetic iron and sulfur bacteria thought by some scientists to be the first organisms on earth?

There are several reasons for this, but they mostly have to do with the way these organisms metabolize, and the ecological composition of the early Earth.


Today, the great majority of organisms use aerobic respiration reactions to generate ATP, and those reactions require fuel, typically glucose or some related carbohydrate. In turn, those carbohydrates tend to be synthesized by organisms that can perform photosynthesis. Both of these reactions are fairly complex and have some irreducible...

There are several reasons for this, but they mostly have to do with the way these organisms metabolize, and the ecological composition of the early Earth.


Today, the great majority of organisms use aerobic respiration reactions to generate ATP, and those reactions require fuel, typically glucose or some related carbohydrate. In turn, those carbohydrates tend to be synthesized by organisms that can perform photosynthesis. Both of these reactions are fairly complex and have some irreducible aspects which indicate that a highly simplified precursor would not have been as likely as an alternative reaction, such as chemotrophy, which provides much less ATP but is capable of being sustained in anaerobic or nutrient-poor environments, such as thermal vents at the ocean floor, where we observe modern-day organisms metabolizing iron and sulfur in a context analogous to that of the early Earth.


We know from fossil records that the oxygen content of the early Earth was exponentially lower than it is today; the great majority of our free oxygen is actually the result of photosynthetic organisms saturating the crust and atmosphere with it. Therefore, the first life would not have been able to utilize reactions that depended on carbon in order to generate energy. Chemotrophs fit this criteria and therefore seem more likely to have been, or at least more closely resembled, the first life.

Popular posts from this blog

In chapter one of The Great Gatsby, what advice does Nick's father give him? How does this make him a good person to tell this story?

Nick says that his father advised him that, before "criticizing anyone," he "remember that all the people in this world haven't had the same advantages" as Nick.  As a result, Nick claims that he is "inclined to reserve all judgments," presenting himself to the reader as a fair and dispassionate arbiter of character, and thus, a reliable narrator.   The problem is that Nick immediately reveals himself as anything but reliable, as he then launches... Nick says that his father advised him that, before "criticizing anyone," he "remember that all the people in this world haven't had the same advantages" as Nick.  As a result, Nick claims that he is "inclined to reserve all judgments," presenting himself to the reader as a fair and dispassionate arbiter of character, and thus, a reliable narrator.   The problem is that Nick immediately reveals himself as anything but reliable, as he then launches into a discussion of how pe...
Post a Comment
Read more

How and why does James Gatz become Jay Gatsby? Describe the young Gatsby/Gatz.

James Gatz, a poor Midwestern boy of probable Jewish lineage, becomes Jay Gatsby, a presumed WASP and wealthy socialite, when he moves to New York City and acquires his fortune. It is wealth that has allowed Gatz to transform himself into Gatsby. However, those who know his background (e.g., Daisy and Tom Buchanan) never allow him to forget that he is nouveau riche -- that is, an upstart who has just recently made his fortune,... James Gatz, a poor Midwestern boy of probable Jewish lineage, becomes Jay Gatsby, a presumed WASP and wealthy socialite, when he moves to New York City and acquires his fortune. It is wealth that has allowed Gatz to transform himself into Gatsby. However, those who know his background (e.g., Daisy and Tom Buchanan) never allow him to forget that he is nouveau riche -- that is, an upstart who has just recently made his fortune, whereas they arose from well-to-do families. Gatz became Gatsby through determination and discipline. At the end of the novel, the narr...
Post a Comment
Read more

Explain and discuss how the definitions of freedom change for the nation, for the freedmen and for southern whites after the Civil War.

After the Civil War, the definition of freedom changed in the nation, as slavery was ended with the 13th Amendment to the Constitution in 1865. The practice of slavery was disallowed, but definition of the freedom that would take its place was a subject of controversy, ongoing debate, and even violence in the decades to come.  For freedmen, freedom often meant reconciling with their families, who were broken up by slavery; choosing which church to... After the Civil War, the definition of freedom changed in the nation, as slavery was ended with the 13th Amendment to the Constitution in 1865. The practice of slavery was disallowed, but definition of the freedom that would take its place was a subject of controversy, ongoing debate, and even violence in the decades to come.  For freedmen, freedom often meant reconciling with their families, who were broken up by slavery; choosing which church to belong to without being ordered to attend religious services (or not to attend) by their mast...
Post a Comment
Read more