Questions for Evolutionists

Homochirality - The problem of left handed amino acids

The problem of homochirality may be summarized by the fact that all of the 20 biologically active amino acids are left handed (apart from one which is so simple that it is neither left or right handed), but that amino acids made in the laboratory are 50% left and 50% right handed. While all proteins are L-amino acids, all sugars are the D form and all nucleic acids in RNA and DNA are the D form.

Why we are made of only left-handed amino acids: the origin of chirality on Earth and in the solar system in beyond ABSTRACT: Most biomolecules are "chiral" or handed, that is to say they exist in two left and right-handed mirror image forms. But biology only uses one hand, i.e. it is "homochiral". One of the greatest puzzles in biophysics is the question of why life on Earth is based on left-handed (L) amino acids and right-handed (D) sugars - why not "mirror life" based on right-handed (D) amino acids and left-handed (L) sugars? The answer may lie in fundamental physics: the parity-violating weak neutral current produces a very slight energy difference between left and right handed molecules, which may become amplified over an evolutionary timescale, and our calculations of this energy difference show that the natural L-amino acids are indeed more stable than their "unnatural" D mirror images. This parity-violating energy difference or "PVED" between mirror image molecules is important not only in biology but also as a "molecular footprint" of fundamental physics: future measurements of the PVED could in effect give us "table-top particle physics", yielding values of the Weinberg angle and other important parameters of fundamental physics much more cheaply with a new generation of spectrometers rather than a new generation of particle accelerators. Homochirality is such a characteristic signature of life that finding molecules all of one hand on other planets could be a signature of life or prebiotic chemistry, and we are building a polarimeter to Search for Extra-Terrestrial Homochirality (SETH) on missions to Mars and other solar system bodies. We are also looking to Search for EXtra-SOlar Homochirality (SEXSOH) by looking for circular polarization in light reflected from planets round other suns in the next century.

We are interested in the origin of biomolecular chirality. Dr Alexandra MacDermott - It is well known that biomolecules are all of one hand, but what determines which hand? Why are animals made of L-amino acids and not D-amino acids? This asymmetry in biology may be a feature of fundamental physics, because it turns out that the "natural" L-amino acids are slightly more stable than their "unnatural" D mirror images, due to the weak force. The weak force, carried by the Z boson recently discovered at CERN, is one of the four forces of nature - electromagnetic, weak, strong and gravity - and it is the only one of the four which can tell the difference between left and right. Due to the weak force, L and D molecules have slightly unequal energies because they are not in fact true mirror images: the true enantiomer of an L-amino acid is the D-amino acid made of anti-matter. We calculate these small energy differences between enantiomers using ab initiomolecular orbital methods. In most cases our calculations do indeed predict the correct sign: not only are the L-amino acids more stable than the D, but the natural D-sugars are more stable than the L, and the right-hand DNA double helix is also more stable than its left-hand mirror image. We believe the slight enantiomeric excess from these "parity-violating energy differences" could be amplified kinetically in the pre-biotic soup to preferentially select today's L-amino acid/D-sugar biochemistry over D-amino acid/L-sugar "mirror life". The parity-violating energy difference between enantiomers is not the only way in which the weak force could select biomolecular chirality. Radioactive beta decay is mediated by the weak force, and this causes a polarization of the electrons emitted in beta decay, which could produce selective destruction of one enantiomer. We are currently starting to develop the theory of this enantioselective beta-radiolysis. Chirality is a characteristic signature of life, and we are collaborating with experimentalists and space engineers to develop a small polarimeter to detect optical rotation as the signature of life on Mars. We also hope to detect the chiral signature of life using polarimetry on the future Darwin space telescopes which will catch light from planets around otherstars: light from an Earth-like planet will show a small circular polarization due to the highly chiral chlorophyll molecules in vegetation cover. Finding molecules of the same hand on many different extra-solar planets would lend support to the weak force theory of the origin of chirality. Some of our team are Co-Investigators on the COSAC experiment of the Rosetta mission, launch 2003, which will use chiral gas chromatography to identify enantiomeric excesses on Comet Wirtanen. We are collaborating with Glaxo Wellcome to use chiroptically detected HPLC to identify chiral molecules in the Murchison and Mars meteorites.

Origin of life: the chirality problem Jonathan Sarfati

Addendum

This NASA article shows amino acids, both flavours, forming in a natural environment, something Miller never accomplished.

This University Science article shows how the flavours of amino acids separate, and promote the evolutionary chemical reactions necessary to begin biological life.

Metamorphosis:

This is another problem for evolutionists, since childhood I have lived just five miles from Down House where Charles Darwin lived in his later years. As a child of about ten years I would collect a caterpillar and keep it in a tank with some weeds and eventually it would change into a chrysalis and next year out from the chysalis would appear a beautiful butterfly.

The question that I have for evolutionists is to explain this cycle: The butterfly lays eggs which hatch as caterpillars which feed on weeds and then form a chrysalis and some months later out comes a butterfly which lays eggs etc.

The caterpillar has no wings or reproductive organs. During the chrysalis stage it must completely rearrange its internal organs and external structure and create some entirely new structures such as reproductive organs and wings. This is called complete metamorphosis. Only the butterfly can reproduce and lay eggs which form caterpillars. See Metamorphism.

Please explain the evolution of this cycle to me. After all the chrysalis stage must be exactly right first time in order to convert a caterpillar into a butterfly. Multiple tries are not allowed. If anyone can give me a plausible answer I will be grateful and you should get the Nobel prize.

Sexual reproduction:

Another puzzle is the origin of sexual reproduction. Firstly this is a large step from asexual reproduction. Secondly this would require that nature conspires to make both a male and female to make it work. Thirdly it would limit the extent of mutational changes because a mutated individual would have to find a compatible mate to reproduce with. Thus the hopeful monster scenario would be limited to small rather than big changes.

1. Sexual Reproduction: A Continuing Mystery to Evolutionists from Evidence for God from Science
2. Why Sexual Reproduction?
3. An Evolutionary Manifesto: A New Hypothesis for Organic Change by John A. Davison, Ph.D.

Abiogenesis:

The real unexplained "mystery" is of course abiogenesis ie. the formation of living cells from chemicals. Time and chance simply does not work, unless you believe in miracles! In order for living cells to have evolved from chemicals a mechanism is required which has yet to be discovered. But suppose a mechanism is discovered, then the 'god of the gaps' disppears into a black hole? See my thoughts on this here.

Loopholes in the evolutionary theory of the origin of life: Summary by Jonathan Sarfati

Origin of life: the polymerization problem Jonathan Sarfati

Self-replicating Enzymes? A critique of some current evolutionary origin-of-life models Jonathan Sarfati

Quantum leap of faith Paul Davies and the origin of life Alexander Williams

The Quest for a Chemical Origin of Life J H John Peet

Cause of the Big Bang?

The next mystery is the cause of the big bang. Did it just happen by happenstance? See the Kalam cosmological argument for the existence of God.

If God created the universe, then who created God? Answering the Critics Jonathan Sarfati

Physical constants just right?

Finally why is it that the fundamental physical constants are "just right" for the universe to exist in its current form and to support life. This is why Barrow and Tipler came up with the Anthropic principle. All the work on fossils assumes that the first living cell evolved from non-life, but the fundamental questions are much earlier on. Even the fossil evidence does not prove any organic descent, rather it is evidence that we can arrange fossils (cladistics).

See also Haldane's Dilemma, Evolution - is it true ? Is it fact or faith? and a rebuttal here.

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