AP Biology 1.2 Evolution Drives the Diversity and Unity of Life
AP® Biology: Evolution Drives the Diversity and Unity of Life Drill 1, Problem 2. What was likely the first genetic material?
|AP Biology||Evolution Drives the Diversity and Unity of Life|
|Common ancestry||Conserved core processes|
|Evolution||Complexity of a Cell|
|Test Prep||AP Biology|
at the molecules in our answer choices...
DNA, RNA, proteins, an RNA-DNA hybrid molecule?
Well, we know the hybrid probably cuts down on fuel emissions... but we're not really
concerned with how "green" it is...
The theory about how life evolved on earth tells us that the first molecules were self-sufficient
because the earth wasn't "made" for us organisms...
and that they were relatively simple because there was nothing else to rely on at first.
Then as successful adaptations were developed due to the changing environment, these molecules
grew more and more complex.
It's how evolution works.
So the "first molecule" we want to find is the one that's the most self-sufficient and simple.
RNA stands for Ribonucleic acid.
It serves several functions in creating proteins for living cells...
It can act as a messenger to carry copies of genetic material...
...transfer amino acids to make proteins, and even self-replicate.
We'd say that's pretty self-sufficient.
We've also heard all about DNA when watching CSI...
and how it carries all of our genetic material...
and how we should never leave our DNA anywhere if we want to get away with some horrific crime.
DNA is a molecule that stands for Deoxy-ribonucleic acid....
which basically differentiates itself from RNA by having a different sugar base...
Deoxyribose instead of ribose.
Hence the difference between the D and R.
But as a piece of genetic material, it only contains the genetic blueprint.
Unlike RNA, it can't self-replicate or create proteins without RNA. So... not too self-sufficient.
Think about C. Proteins?
Well they're needed to interpret genetic information, but they're also the
product of the transformation from DNA to RNA.
So they can't be the first.
Finally, an RNA-DNA hybrid molecule would be nice as the first piece of genetic material...
but based on what we know about RNA, RNA doesn't really need DNA to function on its own.
RNA by itself is simpler...
So RNA is our first genetic material.
Did you fill in that bubble all by yourself?
NOW who's self-sufficient?