Thread: abiogenesis

the method by which life was created is highly debated. the most sound scientific theory is abiogenesis, but creationists and other religious sects have their own views.

my question is how abiogenesis occurs. what is the simplest life that we know of, in other words what life would we expect to arise from abiogenesis? all life shares its use of DNA or RNA, so it's safe to assume that the organism would start off with DNA either in a circle like that of microbes, or in strands such as it is in eukaryotes.

how could this DNA or RNA come into being without a cell to make it? the only ways i've heard of either being created is by already existing cells or by human intervention in a laboratory. and in order for the DNA to be expressed, there would already have to be a lot of cellular machinery. in an abiotic environment, how does this machinery and the other prerequisites of life come into being? do we know, or is this still an unexplored area?

this may be more of an organic chemistry, if a moderator feels it should be moved to chemistry, please feel free.

There are actually many competing hypotheses of abiogenesis.

You're broadly describing the DNA first models, which are generally not thought to be the most likely. The most favoured is the RNA first, since RNA is capable of self-replication and has enzymatic capabilities. The other broad category is protein first, which isn't very popular.

Before you have a cell you would have a proto-cell, and before you had the proto-cell you likely had self-replicating organics like RNA in the environment. Phospholipids we know, once they exist, will form micelles, so if phospholipids, or something like them exist in the environment you can get cells.

Basically we have lots of little pieces of things we know about these compounds. Lipids can form cell like structures spontaneously once they exist. RNAs are capable of storing genetic information and acting as enzymes, and can eventually form the template for the switch over to DNA before life became widespread (or RNA based life eventually went extinct). How we get from some steps to others isn't easy to answer, but there are a lot of ideas out there.

Moreover, you might want to consider metabolism first. In a prebiotic Earth, with no microorganisms to chew up the raw materials, quite complex chemicals, embedded in self sustaining (autocatalytic) cycles could be established. With such cycles secured within micelles (as mentioned by by Sleepy) construction of RNA becomes less of a challenge.

Edited for multiple typos.