Where did the first cell come from?

Question

If every living thing came from a single cell, where did the first cell come from?

Answer 1

No one has a definitive answer yet.

The most probable route is that small self-replicating RNA molecules migrated into phospholipid vesicles, which also grow and split.

There is a lot of interesting research on the subject going on right now. The page linked below is a bit out of date but covers the basics.

Answer 2

The building blocks of life are certain large molecules such as amino acids, which can be 'accidentally' formed in nature (perhaps when lightning strikes the proper soup?).  All known life forms contains DNA or fragments of DNA such as RNA which are also organic molecules that can divide and join to double length or separate to make new cells. Any original cell had to acquire even the simplest molecules plus DNA/RNA encoding to divide and replicate and feed to grow.  This could have occurred within the giant chemistry lab called earth or 'spores' may have arrived from outer space (leaving the question where they came from).  The earth is about 5 billion years old while the universe is perhaps about 15 billions years old and the earth contains heavy elements that originated from long gone supernovas.  Therefore the universe had perhaps three times as much time and far more opportunities than a single planet earth to create life as we know it.  Still, many believe that the earth is very special with an ideal sun at the correct heating distance, the right size planet regarding gravity and the ability to hold a protective atmosphere regarding lethal UV light.  I vote for the creation of life on earth (but who knows how many distant planets in our galaxy or distant galaxies also succeeded long ago or will far into the future?).

Answer 3

Good question - and science does not (yet) have a fully-worked-out answer.

The area of research regarding this is called "abiogenesis".

Possibly the best-accepted current theory is the "RNA world" hypothesis, which suggests that self-replicating molecules of RNA were the first forms of "life", and that the association with DNA, proteins, and lipids came later.

Check the wikipedia link below - it gives an excellent primer of the major areas.