In part 3 of this series, I’ll take two of the claims made by the Strength’s and Weaknesses website, as they really are the same thing. I’m not sure if the author thinks that they are two different things or what, but it is odd. Of course, while the science is not settled, it is far from the claims of the website.
- No known way to achieve 100% left-handed amino acids in proteins or the 100% right-handed sugars in RNA and DNA – all of which are universal to life systems.
- All natural processes are known to produce a 50-50% mixture of left-handed and right-handed molecules.
The issue here is fairly simple. Many molecules have mirror images of each other.
These two molecules ((S)-Alanine and (R)-Alanine) are exactly the same chemically CH3CH(NH2)COOH. But they are mirror images of each other. These are called enantiomers. There is no way to rotate the molecule on the left so that it matches the molecule on the right. Chemically, it’s no big deal, but structurally, it’s a huge deal. Because the biochemistry of our bodies are very, very specific. And our bodily systems can tell the difference between the two.
One of those molecules is very important to proteins in our body, the other is completely useless. A different shape means that a protein formed by the molecule will have a different shape and that could easily destroy the entire function of the protein.
Organisms on the Earth use only left-handed amino acids and only right-handed sugars.
The issue is that, if you create amino acids or sugars in a lab using normal processes, then you end up with approximately 50% left-handed molecules and 50% right-handed molecules. This is called a racemic mixture.
How can we get from 50/50 to all of one kind? The creationists say that this is impossible. I say that they are wrong and have been for a long time.
Here’s a term paper by a graduate student that describes no fewer than six methods that non 50/50 ratios of enantiomers can occur. He has 37 references, about 35 of which are directly related to determining the origin of homochirality.
Here are a few of the more popular ones:
- Mirror-symmetry breaking – Some physical characteristic causes a non-50/50 ratio. One causes that is known to actually happen is circularly polarized light.
- Chiral amplification – Any asymmetry can be increased by autocatalytic reactions (here, here, and here)
- Biological amplification – biochemical interactions among molecules only works with molecules of the same handedness. Addition of a different handed molecule to a chain (protein or RNA/DNA) terminates the chain.
- Energy state of the different enantiomers –
Note that the last paper on this list (Joyce, et. al) was published in 1985. This isn’t brand new science.
I’ll add one more bit here. Biochemically, sugars must be the opposite handedness of the amino acids. The biochemistry of organisms on Earth won’t work any other way… mostly. Like everything else, there are exceptions.
So again, we see that the claims of creationists have not only been shown to be false, but they have been known for decades.
Will we ever know EXACTLY how it happened? No. That kind of thing is never fossilized and is buried in time. But if it’s possible, then that’s enough. There is no physical or chemical reason why it can’t happen, in spite of what creationists say.