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The genetic code is redundant, there are 20 amino acids for 64 possible nucleotide combinations (triplet codons). Therefore some amino acid are coded by several different codons. While leucine is coded by 6 codons, tryptophan is coded only by one codon.
[I am aware that the set of codons that code for one given amino acid tend to look alike each other more than random. Usually it is only the last base that does not affect the amino-acid that is encoded.]
I therefore do not think that the genetic code can be entirely be explained by “it happened to occur that way the first time” (at the origin of life or in the last universal common ancestor) “and it never changed”.
So, my questions are:
Why are some amino acids coded by a several codons while others are coded only by one or two?
Specifically, why is methionine coded by only one codon - AUG - which has also to serve as a start signal?
In general, how (by what mechanisms, selective pressures) has the genetic code evolved to give this pattern of redundancies?
This question is closely related, and the fascinating link posted by @JohnSmith is a good read.
In short, with a four-base system, and a codon size of 1, you get four possible amino acids. Silly system. A codon size of 2 gives 16. Not too shabby, but not a lot of room for growth, and not enough for those 20 amino acids. Codons of size 3 gives 64 - plenty of room to work with and it covers all your forseeable amino acids, and then some, without being too wasteful.
The redundancy, known as degeneracy, is pretty straightforward. There's room to expand, and any redundancy/degeneracy will only reduce the likelihood of errors. That's a huge benefit. For some amino acids, the first two bases are enough. That third position can be quite tolerant to mutation, which is very beneficial to organisms. It appears to be even more fine-tuned, to the degree that redundancy often not only reduces the likelihood of mutation but also reduces the damage caused when a base does mutate. Swapping a hydrophobic AA for another hydrophobic one is less likely to cause aberrant protein function, and anything with a U in the middle is probably hydrophobic. Convenient! I'll also note that, while it's not perfect or even a significant correlation, the more popular amino acids tend to get more redundancy; tryptophan is traditionally the least common AA.
Finally, there are a few non-proteinogenic amino acids, so, as the linked question/answer above points out, maybe in the future there will be more amino acids.
It seems that duplicate codons make translation more robust and resistant to translational misreading. There are four theories that explain existence of duplicate codons:
- Stereochemical theory
- Coevolution theory
- Error minimization theory
- Frozen accident hypothesis
They are not mutually exclusive and “Origin and evolution of the genetic code: the universal enigma” paper attempts to reconcile them:
Mathematical analysis of the structure and possible evolutionary trajectories of the code shows that it is highly robust to translational misreading but there are numerous more robust codes, so the standard code potentially could evolve from a random code via a short sequence of codon series reassignments. Thus, much of the evolution that led to the standard code could be a combination of frozen accident with selection for error minimization although contributions from coevolution of the code with metabolic pathways and weak affinities between amino acids and nucleotide triplets cannot be ruled out. However, such scenarios for the code evolution are based on formal schemes whose relevance to the actual primordial evolution is uncertain. A real understanding of the code origin and evolution is likely to be attainable only in conjunction with a credible scenario for the evolution of the coding principle itself and the translation system.
From my understanding the idea is that codons are grouped by selection for physico-chemical properties of corresponding amino-acids so a random one nucleotide mutation wouldn't change properties or a corresponding amino-acids too dramatic.
Some elements of response to your question.
First, something about tRNA frequency. Even if there are six codons for a given amino acid, they are not equivalent because some will correspond to abundant tRNA, while others correspond to very minor tRNA. This has significant influence on the traduction speed, as the traduction will dramatically slow down on minor tRNA (while the ribosome waits for the proper tRNA). This may have very important impact on the folding of proteins (see for instance this paper: http://dx.doi.org/10.1371/journal.pone.0002189). Having several codons for common amino-acids may actually be a powerful fine-tuning too for the folding of proteins.
Second, as in some cases (splicing, selenocysteine insertion, what else ?), the secondary structure of the mRNA produced is extremely important, the organisms must be able to tweak the sequence of RNA to leave room for that to happen, and that can only happen if there are lots of amino acids for which there is latitude to tweak the produced mRNA sequence.
Third, it is false that the genetic code is universal. There are some evolutions of the genetic code, see for instance the specific case of methionine in mitochondria: http://dx.doi.org/10.1073/pnas.0802779105.
How did the genetic code evolve? - Biology
Proteins, encoded by individual genes, orchestrate nearly every function of the cell.
Describe transcription and translation
- Genes are composed of DNA arranged on chromosomes.
- Some genes encode structural or regulatory RNAs. Other genes encode proteins.
- Replication copies DNA transcription uses DNA to make complementary RNAs translation uses mRNAs to make proteins.
- In eukaryotic cells, replication and transcription take place within the nucleus while translation takes place in the cytoplasm.
- In prokaryotic cells, replication, transcription, and translation occur in the cytoplasm.
- DNA: a biopolymer of deoxyribonucleic acids (a type of nucleic acid) that has four different chemical groups, called bases: adenine, guanine, cytosine, and thymine
- messenger RNA: Messenger RNA (mRNA) is a molecule of RNA that encodes a chemical “blueprint” for a protein product.
- protein: any of numerous large, complex naturally-produced molecules composed of one or more long chains of amino acids, in which the amino acid groups are held together by peptide bonds
Genes and Proteins
Since the rediscovery of Mendel’s work in 1900, the definition of the gene has progressed from an abstract unit of heredity to a tangible molecular entity capable of replication, transcription, translation, and mutation. Genes are composed of DNA and are linearly arranged on chromosomes. Some genes encode structural and regulatory RNAs. There is increasing evidence from research that profiles the transcriptome of cells (the complete set all RNA transcripts present in a cell) that these may be the largest classes of RNAs produced by eukaryotic cells, far outnumbering the protein-encoding messenger RNAs (mRNAs), but the 20,000 protein-encoding genes typically found in animal cells, and the 30,o00 protein-encoding genes typically found in plant cells, nonetheless have huge impacts on cellular functioning.
Protein-encoding genes specify the sequences of amino acids, which are the building blocks of proteins. In turn, proteins are responsible for orchestrating nearly every function of the cell. Both protein-encoding genes and the proteins that are their gene products are absolutely essential to life as we know it.
Genes Encode Proteins: Genes, which are carried on (a) chromosomes, are linearly-organized instructions for making the RNA and protein molecules that are necessary for all of processes of life. The (b) interleukin-2 protein and (c) alpha-2u-globulin protein are just two examples of the array of different molecular structures that are encoded by genes.
Replication, Transcription, and Translation are the three main processes used by all cells to maintain their genetic information and to convert the genetic information encoded in DNA into gene products, which are either RNAs or proteins, depending on the gene. In eukaryotic cells, or those cells that have a nucleus, replication and transcription take place within the nucleus while translation takes place outside of the nucleus in cytoplasm. In prokaryotic cells, or those cells that do not have a nucleus, all three processes occur in the cytoplasm.
Replication is the basis for biological inheritance. It copies a cell’s DNA. The enzyme DNA polymerase copies a single parental double-stranded DNA molecule into two daughter double-stranded DNA molecules. Transcription makes RNA from DNA. The enzyme RNA polymerase creates an RNA molecule that is complementary to a gene-encoding stretch of DNA. Translation makes protein from mRNA. The ribosome generates a polypeptide chain of amino acids using mRNA as a template. The polypeptide chain folds up to become a protein.
5.8 Using the genetic code
DNA is transcribed into RNA, which is translated into a polypeptide. Simply, a series consisting of four bases (A,G,C,T) is transcribed and translated into a series of 20 amino acids. This shift from one chemical language to another is accomplished through the genetic code, a set of precise rules that govern how every possible sequence of three RNA nucleotides (a codon) corresponds to a specific amino acid.
The genetic code can be read as a table, whereby each three-letter codon is broken into its first, second and third RNA bases. These bases converge on a single amino acid, and this amino acid is the actual translated product of the original DNA nucleotides. For example, figure 6 tells us that the amino acid tyrosine (Tyr) corresponds to the mRNA codon UAC. The genetic code also contains an initiation (or “start”) codon, AUG, and three “stop” codons: UAA, UAG, UGA. The initiation codon also codes for the amino acid Methionine. Methionine (with Tryptophan) is one of only two amino acids that correspond to a single codon. Most amino acids correspond to several three- base `sequences. In other words, the genetic code can be very redundant.
Figure 5.9 The genetic code consists of all the RNA codons and their associated amino acids.
What else does DNA do?
Only 2% of the human genome codes for proteins, leading some scientists to refer to the remaining nucleotides as “junk DNA.” However, this moniker may be too harsh. Rather, it seems that much of your DNA is regulatory, and controls how much, or what kind, of a protein is synthesized. Some DNA is part of a gene that was active in our ancestors, but is no longer functional for example, humans have several vestigial olfactory genes, suggesting that modern humans are not as dependent on our sense of smell as were our hominid ancestors. And some DNA was adopted from viruses that attacked human ancestors these endogenous retroviruses say a lot about our evolutionary past with pathogens, but are not functioning genes.
It is also probable that many DNA sequences have functions yet to be identified. In 2012, a consortium of scientists reported on a decade-long project, The Encyclopedia of DNA Elements (ENCODE), suggesting that over 80% of DNA is somehow functional. ENCODE’s results have been applauded and criticized, a span of responses that highlights how DNA science is still in its infancy. Regardless of the exact percentages, it is clear that while much of our DNA does not directly code for protein, the human genome is far from being packed with junk.
Types of Genetic Mutations
Because the genetic code contains the information to make the stuff of life, errors in an organism’s DNA can have catastrophic consequences. Errors can happen during DNA replication if the wrong base pair is added to a DNA strand, if a base is skipped, or if an extra base is added.
Rarely, these errors may actually be helpful – the “mistaken” version of the DNA may work better than the original, or have an entirely new function! In that case, the new version may become more successful, and its carrier may outcompete carriers of the old version in the population. This spread of new traits throughout a population is how evolution progresses.
Silent Mutations and Redundant Coding
In some cases, genetic mutations may not have any effect at all on the end product of a protein. This is because, as seen in the table above, most amino acids are connected to more than one codon.
Glycine, for example, is coded for by the codons GGA, GGC, GGG, and GGU. A mutation resulting in the wrong nucleotide being used for the last letter of the glycine codon, then, would make no difference. A codon starting in “GG” would still code for glycine, no matter what letter was used last.
The use of multiple codons for the same amino acid is thought to be a mechanism evolved over time to minimize the chance of a small mutation causing problems for an organism.
In a missense mutation, the substitution of one base pair for an incorrect base pair during DNA replication results in the wrong amino acid being used in a protein.
This may have a small affect on an organism, or a large one – depending on how important the amino acid is to the function of its protein, and what protein is effected.
This can be thought of like furniture construction. How bad would it be if you used the wrong piece to bolt a chair leg in place? If you used a screw instead of a nail, the two are probably similar enough that the chair leg would stay on – but if you tried to use, say, a seat cushion to connect the leg to the chair, your chair wouldn’t work very well!
A missense mutation may result in an enzyme that almost as well as the normal version – or an enzyme that does not function at all.
A nonsense mutation occurs when the incorrect base pair is used during DNA replication – but where the resulting codon does not code for an incorrect amino acid.
Instead, this error creates a stop codon or another piece of information that is indecipherable to the cell. As a result, the ribosome stops working on that protein and all subsequent codons are not transcribed!
Nonsense mutations lead to incomplete proteins, which may function very poorly or not at all. Imagine if you stopped assembling a chair halfway through!
In a deletion mutation, one or more DNA bases are not copied during DNA replication. Deletion mutations come in a huge range of sizes – a single base pair may be missing, or a large piece of a chromosome may be missing!
Smaller mutations are not always less harmful. The loss of just one or two bases can result in a frameshift mutation that impairs a crucial gene, as discussed under “frameshift mutations” below.
By contrast, larger deletion mutations may be fatal – or may only result in disability, as in DiGeorge Syndrome and other conditions that result from the deletion of part of a chromosome.
The reason for this is that DNA is very much like computer source code – one piece of code might be crucial for the system to turn on at all, while other pieces of code might just ensure that a website looks pretty or loads quickly.
Depending on the function of the piece of code that is deleted or otherwise mutated, a small change can have catastrophic consequences – or a seemingly large corruption of code one can result in a system that is just a bit glitchy.
An insertion mutation occurs when one or more nucleotides is erroneously added to a growing DNA strand during DNA replication. On rare occasions, long stretches of DNA may be incorrectly added in the middle of a gene.
Like a missense mutation, the impact of this can vary. The addition of an unnecessary amino acid in a protein may make the protein only slightly less efficient or it may cripple it.
Consider what would happen to your chair if you added a random piece of wood to it that the instructions did not call for. The results could vary a lot depending on the size, shape, and placement of the extra piece!
A duplication mutation occurs when a segment of DNA is accidentally replicated two or more times. Like the other mutations listed above, these may have mild effects – or they may be catastrophic.
To imagine if your chair had two backs, two seats, or eight legs. A small duplication and the chair may still be useable, if a little odd-looking or uncomfortable. But if the chair had, for example, six seats attached to each other, it may rapidly become useless for its intended purpose!
A frameshift mutation is a subtype of insertion, deletion, and duplication mutations. In a frameshift mutation, one or two amino acids are deleted or inserted – resulting in a shifting of the “frame” which the ribosome uses to tell where one codon stops and the next begins.
This type of error can be especially dangerous because it causes all codons that occur after the error to be misread. Typically, every amino acid added to the protein after the frameshift mutation is wrong.
Imagine if you were reading a book – but at some point during the writing, a programming error happened such that every subsequent letter shifted one letter later in the alphabet.
A word that was supposed to read “letter” would suddenly become “mfuuft.” Boe tp po.
This is approximately what happens in a frameshift mutation.
1. The base pairing rules of DNA and RNA are as follows:
- A – T/U (Uracil is used instead of thymine in RNA.)
- C – G
- G – C
- T/U – A
Given that, which of the following would be the anti-codon sequence for an mRNA codon reading “UUGCUGCAG?”
2. Which of the following could NOT occur as a result of the deletion of a single nucleotide?
A. A missense error.
B. A nonsense error.
C. A frameshift mutation.
D. None of the above.
3. What amino acid string is coded for by the mRNA sequence UUGCUGCAG?
DNA and the Origin of LifeInformation, Specification, and Explanation Stephen C. Meyer August 1, 2003 Abstract: Many origin-of-life researchers now regard the origin of biological information as the central problem facing origin-of-life research. Yet, the term 'information' can designate several theoretically distinct concepts. By distinguishing between specified and unspecified information, this essay seeks to eliminate definitional ambiguity associated with the term 'information' as used in biology. It does this in order to evaluate competing explanations for the origin of biological information. In particular, this essay challenges the causal adequacy of naturalistic chemical evolutionary explanations for the origin of specified biological information, whether based upon "chance," "necessity," or the combination. Instead, it argues that our present knowledge of causal powers suggests intelligent design or agent causation as a better, more causally adequate, explanation for the origin of specified biological information. Read More .
Intelligent Design as a Theory of Information
Origin and evolution of the genetic code: the universal enigma
The genetic code is nearly universal, and the arrangement of the codons in the standard codon table is highly nonrandom. The three main concepts on the origin and evolution of the code are the stereochemical theory, according to which codon assignments are dictated by physicochemical affinity between amino acids and the cognate codons (anticodons) the coevolution theory, which posits that the code structure coevolved with amino acid biosynthesis pathways and the error minimization theory under which selection to minimize the adverse effect of point mutations and translation errors was the principal factor of the code's evolution. These theories are not mutually exclusive and are also compatible with the frozen accident hypothesis, that is, the notion that the standard code might have no special properties but was fixed simply because all extant life forms share a common ancestor, with subsequent changes to the code, mostly, precluded by the deleterious effect of codon reassignment. Mathematical analysis of the structure and possible evolutionary trajectories of the code shows that it is highly robust to translational misreading but there are numerous more robust codes, so the standard code potentially could evolve from a random code via a short sequence of codon series reassignments. Thus, much of the evolution that led to the standard code could be a combination of frozen accident with selection for error minimization although contributions from coevolution of the code with metabolic pathways and weak affinities between amino acids and nucleotide triplets cannot be ruled out. However, such scenarios for the code evolution are based on formal schemes whose relevance to the actual primordial evolution is uncertain. A real understanding of the code origin and evolution is likely to be attainable only in conjunction with a credible scenario for the evolution of the coding principle itself and the translation system.
The standard genetic code. The…
The standard genetic code. The codon series are shaded in accordance with the…
An optimized genetic code with…
An optimized genetic code with the same block structure and degeneracy as the…
Evolution of codes in a rugged fitness landscape (a cartoon illustration). r 1…
The expansion of the standard…
The expansion of the standard code according to the coevolution theory. Phase 1…
Genetic Code Evolution and Darwin’s Evolution Theory Should Consider DNA an ‘Energy Code’
Darwin’s theory of evolution should be expanded to include consideration of a DNA stability “energy code” – so-called “molecular Darwinism” – to further account for the long-term survival of species’ characteristics on Earth, according to Rutgers scientists.
The iconic genetic code can be viewed as an “energy code” that evolved by following the laws of thermodynamics (flow of energy), causing its evolution to culminate in a nearly singular code for all living species, according to the Rutgers co-authored study in the journal Quarterly Reviews of Biophysics .
“ These revelations matter because they provide entirely new ways of analyzing the human genome and the genome of any living species, the blueprints of life,” said senior author Kenneth J. Breslauer , Linus C. Pauling Distinguished University Professor in the Department of Chemistry and Chemical Biology in the School of Arts and Sciences at Rutgers University–New Brunswick . He is also affiliated with the Rutgers Cancer Institute of New Jersey . “The origins of the evolution of the DNA genetic code and the evolution of all living species are embedded in the different energy profiles of their molecular DNA blueprints. Under the influence of the laws of thermodynamics, this energy code evolved, out of an astronomical number of alternative possibilities, into a nearly singular code across all living species.”
Scientists investigated this so-called “universal enigma,” probing the origins of the astounding observation that the genetic code evolved into a nearly uniform blueprint that arose from trillions of possibilities.
The scientists expanded the underpinnings of the landmark “survival of the fittest” Darwinian evolutionary theory to include “molecular Darwinism.” Darwin’s revolutionary theory is based on the generational persistence of a species’ physical features that allow it to survive in a given environment through “natural selection.” Molecular Darwinism refers to physical characteristics that persist through generations because the regions of the molecular DNA that code for those traits are unusually stable.
Different DNA regions can exhibit differential energy signatures that may favor physical structures in organisms that enable specific biological functions, Breslauer said.
Next steps include recasting and mapping the human genome chemical sequence into an “energy genome,” so DNA regions with different energy stabilities can be correlated with physical structures and biological functions. That would enable better selection of DNA targets for molecular-based therapeutics.
Jens Völker, an associate research professor in Rutgers–New Brunswick’s Department of Chemistry and Chemical Biology, co-authored the study, along with first author Horst H. Klump at the University of Cape Town.
This is because the genetic machinery evolved to account for 20 amino acids - the building blocks of proteins - reaching a point where was unable to expand to include more, essentially remaining frozen in time for more than three billion years.
While the human body can jumble and link these available amino acids together to make proteins, it uses additional amino acids which aren't involved in genetic machinery, relying instead on complicated chemical pathways.
Scientists believe our genetic code has been frozen in its current form for billions of years, unable to expand due to a lack of molecules (pictured, shaped like a map of the Britain). These molecules shuttle building blocks of proteins to cells but there are only enough sufficiently different ones to handle 20 amino acids
THE GENETIC ROADBLOCK
The genetic code can only use 20 amino acids building blocks to make proteins, and is unable to expand beyond this.
Using more than 20 amino acids would cause the system to collapse, as the genetic machinery would likely misread instructions, leading to malfunctioning proteins.
In theory, the code could have expanded to use 63 amino acids, but hit this genetic road block billions of years ago.
Scientists believe that the limit is due lack of different RNA molecules - which shuttle the amino acids to the site of assembly.
Scientists believe the emerging field of synthetic biology could overcome the limitations of mother nature and extend the code further.
In theory, the genetic code could have expanded to use 63 amino acids, but hit its 'genetic road block' billions of years ago.
But if the machinery that reads DNA and translates it to proteins had to include any more than 20, it is highly likely errors would constantly creep into production process.
This would lead to faulty proteins and an eventual meltdown of the biological system.
'Protein synthesis based on the genetic code is the decisive feature of biological systems and it is crucial to ensure faithful translation of information,' explained Professor Lluís Ribas de Pouplana, a geneticist from the Institute for Research in Biomedicine (IRB Barcelona) and senior author of the study.
Each tRNA has two key regions, linking to a specific amino acid at one end,
The other recognises a three-letter stamp of genetic code – but the multiple genetic stamps can code for the same amino acid. The combination of these regions give each tRNA an identity.
According to the team, the reason the genetic code wasn't able to expand beyond the 20 is because it wasn't possible to create any new tRNAs without the system getting confused.
Professor Ribas told MailOnline: 'Our work shows that the central pieces of the genetic code, the transfer RNAs, can not house enough specific identity elements for the system to be able to distinguish 63 of them.
Each tRNA has two key regions, the combination of which gives it an identity. According to the team, the genetic code was left 'frozen' in time and unable to expand because it couldn't generate any new tRNAs without the system getting confused, leading to 'catastrophic errors'
Geneticists believe the emerging field of synthetic biology could be explored as a means to overcoming the limitations of Mother Nature, extending the code far beyond its frozen state (stock image)
'Since you need a new tRNA for each new amino acid, once the limit of tRNAs is reached that determines how many amino acids you can use. This limit happened to be at 20, and it hasn't changed for 3 billion years.'
But the team is looking to the emerging field of synthetic biology to overcome the limitations of mother nature and extend the code further.
Professor Ribas explained: 'It is thus unlikely that the limit will change naturally, and you could certainly call it a bottle neck for molecular diversity.
'Artificially, however, we are able to increase the number of amino acids used by cells under controlled laboratory conditions. I think that our work adds to the notion that adding new amino acids in a natural context would require very dramatic engineering of the system.
'Something that nature can't do. How to go about this engineering is the main question that opens after our study.'
How is molecular biology evidence of evolution?
Also to know is, how does molecular biology provide evidence for evolution?
Molecular similarities provide evidence for the shared ancestry of life. DNA sequences comparisons can show how closely species are related. Biogeography, the study of the geographical distribution of organisms, provides information about how and when species may have evolved.
Additionally, how do fossils provide evidence for evolution? Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today. Paleontologists can determine the age of fossils using methods like radiometric dating and categorize them to determine the evolutionary relationships between organisms.
Besides, why is molecular biology important to evolution?
One of the most useful advances has been the development of molecular biology. In this field, scientists look at the proteins and other molecules that control life processes. While these molecules can evolve just as an entire organism can, some important molecules are highly conserved among species.
DNA: The Tiny Code That's Toppling Evolution
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Two great achievements occurred in 1953, more than half a century ago.
The first was the successful ascent of Mt. Everest, the highest mountain in the world. Sir Edmund Hillary and his guide, Tenzing Norgay, reached the summit that year, an accomplishment that's still considered the ultimate feat for mountain climbers. Since then, more than a thousand mountaineers have made it to the top, and each year hundreds more attempt it.
Yet the second great achievement of 1953 has had a greater impact on the world. Each year, many thousands join the ranks of those participating in this accomplishment, hoping to ascend to fame and fortune.
It was in 1953 that James Watson and Francis Crick achieved what appeared impossible—discovering the genetic structure deep inside the nucleus of our cells. We call this genetic material DNA, an abbreviation for deoxyribonucleic acid.
The discovery of the double-helix structure of the DNA molecule opened the floodgates for scientists to examine the code embedded within it. Now, more than half a century after the initial discovery, the DNA code has been deciphered—although many of its elements are still not well understood.
What has been found has profound implications regarding Darwinian evolution, the theory taught in schools all over the world that all living beings have evolved by natural processes through mutation and natural selection.
Amazing revelations about DNA
As scientists began to decode the human DNA molecule, they found something quite unexpected—an exquisite 'language' composed of some 3 billion genetic letters. "One of the most extraordinary discoveries of the twentieth century," says Dr. Stephen Meyer, director of the Center for Science and Culture at the Discovery Institute in Seattle, Wash., "was that DNA actually stores information—the detailed instructions for assembling proteins—in the form of a four-character digital code" (quoted by Lee Strobel, The Case for a Creator, 2004, p. 224).
It is hard to fathom, but the amount of information in human DNA is roughly equivalent to 12 sets of The Encyclopaedia Britannica—an incredible 384 volumes" worth of detailed information that would fill 48 feet of library shelves!
Yet in their actual size—which is only two millionths of a millimeter thick—a teaspoon of DNA, according to molecular biologist Michael Denton, could contain all the information needed to build the proteins for all the species of organisms that have ever lived on the earth, and "there would still be enough room left for all the information in every book ever written" (Evolution: A Theory in Crisis, 1996, p. 334).
Who or what could miniaturize such information and place this enormous number of 'letters' in their proper sequence as a genetic instruction manual? Could evolution have gradually come up with a system like this?
DNA contains a genetic language
Let's first consider some of the characteristics of this genetic 'language.' For it to be rightly called a language, it must contain the following elements: an alphabet or coding system, correct spelling, grammar (a proper arrangement of the words), meaning (semantics) and an intended purpose.
Scientists have found the genetic code has all of these key elements. "The coding regions of DNA," explains Dr. Stephen Meyer, "have exactly the same relevant properties as a computer code or language" (quoted by Strobel, p. 237, emphasis in original).
The only other codes found to be true languages are all of human origin. Although we do find that dogs bark when they perceive danger, bees dance to point other bees to a source and whales emit sounds, to name a few examples of other species" communication, none of these have the composition of a language. They are only considered low-level communication signals.
The only types of communication considered high-level are human languages, artificial languages such as computer and Morse codes and the genetic code. No other communication system has been found to contain the basic characteristics of a language.
Bill Gates, founder of Microsoft, commented that "DNA is like a software program, only much more complex than anything we've ever devised."
Can you imagine something more intricate than the most complex program running on a supercomputer being devised by accident through evolution—no matter how much time, how many mutations and how much natural selection are taken into account?
DNA language not the same as DNA molecule
Recent studies in information theory have come up with some astounding conclusions—namely, that information cannot be considered in the same category as matter and energy. It's true that matter or energy can carry information, but they are not the same as information itself.
For instance, a book such as Homer's Iliad contains information, but is the physical book itself information? No, the materials of the book—the paper, ink and glue contain the contents, but they are only a means of transporting it.
If the information in the book was spoken aloud, written in chalk or electronically reproduced in a computer, the information does not suffer qualitatively from the means of transporting it. "In fact the content of the message," says professor Phillip Johnson, "is independent of the physical makeup of the medium" (Defeating Darwinism by Opening Minds, 1997, p. 71).
The same principle is found in the genetic code. The DNA molecule carries the genetic language, but the language itself is independent of its carrier. The same genetic information can be written in a book, stored in a compact disk or sent over the Internet, and yet the quality or content of the message has not changed by changing the means of conveying it.
As George Williams puts it: "The gene is a package of information, not an object. The pattern of base pairs in a DNA molecule specifies the gene. But the DNA molecule is the medium, it's not the message" (quoted by Johnson, p. 70).
Information from an intelligent source
In addition, this type of high-level information has been found to originate only from an intelligent source.
As Lee Strobel explains: "The data at the core of life is not disorganized, it's not simply orderly like salt crystals, but it's complex and specific information that can accomplish a bewildering task—the building of biological machines that far outstrip human technological capabilities" (p. 244).
For instance, the precision of this genetic language is such that the average mistake that is not caught turns out to be one error per 10 billion letters. If a mistake occurs in one of the most significant parts of the code, which is in the genes, it can cause a disease such as sickle-cell anemia. Yet even the best and most intelligent typist in the world couldn't come close to making only one mistake per 10 billion letters—far from it.
So to believe that the genetic code gradually evolved in Darwinian style would break all the known rules of how matter, energy and the laws of nature work. In fact, there has not been found in nature any example of one information system inside the cell gradually evolving into another functional information program.
Michael Behe, a biochemist and professor at Pennsylvania's Lehigh University, explains that genetic information is primarily an instruction manual and gives some examples.
He writes: "Consider a step-by-step list of [genetic] instructions. A mutation is a change in one of the lines of instructions. So instead of saying, "Take a 1/4-inch nut," a mutation might say, "Take a 3/8-inch nut." Or instead of "Place the round peg in the round hole," we might get "Place the round peg in the square hole" . . . What a mutation cannot do is change all the instructions in one step—say, [providing instructions] to build a fax machine instead of a radio" (Darwin's Black Box, 1996, p. 41).
We therefore have in the genetic code an immensely complex instruction manual that has been majestically designed by a more intelligent source than human beings.
Even one of the discoverers of the genetic code, the agnostic and recently deceased Francis Crick, after decades of work on deciphering it, admitted that "an honest man, armed with all the knowledge available to us now, could only state that in some sense, the origin of life appears at the moment to be almost a miracle, so many are the conditions which would have had to have been satisfied to get it going" (Life Itself, 1981, p. 88, emphasis added).
Evolution fails to provide answers
It is good to remember that, in spite of all the efforts of all the scientific laboratories around the world working over many decades, they have not been able to produce so much as a single human hair. How much more difficult is it to produce an entire body consisting of some 100 trillion cells!
Up to now, Darwinian evolutionists could try to counter their detractors with some possible explanations for the complexity of life. But now they have to face the information dilemma: How can meaningful, precise information be created by accident—by mutation and natural selection? None of these contain the mechanism of intelligence, a requirement for creating complex information such as that found in the genetic code.
Darwinian evolution is still taught in most schools as though it were fact. But it is increasingly being found wanting by a growing number of scientists. "As recently as twenty-five years ago," says former atheist Patrick Glynn, "a reasonable person weighing the purely scientific evidence on the issue would likely have come down on the side of skepticism [regarding a Creator]. That is no longer the case." He adds: "Today the concrete data point strongly in the direction of the God hypothesis. It is the simplest and most obvious solution . . ." (God: The Evidence, 1997, pp. 54-55, 53).
Quality of genetic information the same
Evolution tells us that through chance mutations and natural selection, living things evolve. Yet to evolve means to gradually change certain aspects of some living thing until it becomes another type of creature, and this can only be done by changing the genetic information.
So what do we find about the genetic code? The same basic quality of information exists in a humble bacteria or a plant as in a person. A bacterium has a shorter genetic code, but qualitatively it gives instructions as precisely and exquisitely as that of a human being. We find the same prerequisites of a language—alphabet, grammar and semantics—in simple bacteria and algae as in man.
Each cell with genetic information, from bacteria to man, according to molecular biologist Michael Denton, consists of "artificial languages and their decoding systems, memory banks for information storage and retrieval, elegant control systems regulating the automated assembly of parts and components, error fail-safe and proof-reading devices utilized for quality control, assembly processes involving the principle of prefabrication and modular construction . . . [and a] capacity not equalled in any of our most advanced machines, for it would be capable of replicating its entire structure within a matter of a few hours" (Denton, p. 329).
So how could the genetic information of bacteria gradually evolve into information for another type of being, when only one or a few minor mistakes in the millions of letters in that bacterium's DNA can kill it?
Again, evolutionists are uncharacteristically silent on the subject. They don't even have a working hypothesis about it. Lee Strobel writes: "The six feet of DNA coiled inside every one of our body's one hundred trillion cells contains a four-letter chemical alphabet that spells out precise assembly instructions for all the proteins from which our bodies are made . . . No hypothesis has come close to explaining how information got into biological matter by naturalistic means" (Strobel, p. 282).
Werner Gitt, professor of information systems, puts it succinctly: "The basic flaw of all evolutionary views is the origin of the information in living beings. It has never been shown that a coding system and semantic information could originate by itself [through matter] . . . The information theorems predict that this will never be possible. A purely material origin of life is thus [ruled out]" (Gitt, p. 124).
Besides all the evidence we have covered for the intelligent design of DNA information, there is still one amazing fact remaining—the ideal number of genetic letters in the DNA code for storage and translation.
Moreover, the copying mechanism of DNA, to meet maximum effectiveness, requires the number of letters in each word to be an even number. Of all possible mathematical combinations, the ideal number for storage and transcription has been calculated to be four letters.
This is exactly what has been found in the genes of every living thing on earth—a four-letter digital code. As Werner Gitt states: "The coding system used for living beings is optimal from an engineering standpoint. This fact strengthens the argument that it was a case of purposeful design rather that a [lucky] chance" (Gitt, p. 95).
Back in Darwin's day, when his book On the Origin of Species was published in 1859, life appeared much simpler. Viewed through the primitive microscopes of the day, the cell appeared to be but a simple blob of jelly or uncomplicated protoplasm. Now, almost 150 years later, that view has changed dramatically as science has discovered a virtual universe inside the cell.
"It was once expected," writes Professor Behe, "that the basis of life would be exceedingly simple. That expectation has been smashed. Vision, motion, and other biological functions have proven to be no less sophisticated than television cameras and automobiles. Science has made enormous progress in understanding how the chemistry of life works, but the elegance and complexity of biological systems at the molecular level have paralyzed science's attempt to explain their origins" (Behe, p. x).
Dr. Meyer considers the recent discoveries about DNA as the Achilles" heel of evolutionary theory. He observes: "Evolutionists are still trying to apply Darwin's nineteenth-century thinking to a twenty-first century reality, and it's not working . I think the information revolution taking place in biology is sounding the death knell for Darwinism and chemical evolutionary theories" (quoted by Strobel, p. 243).
Dr. Meyer's conclusion? "I believe that the testimony of science supports theism. While there will always be points of tension or unresolved conflict, the major developments in science in the past five decades have been running in a strongly theistic direction" (ibid., p. 77).
Dean Kenyon, a biology professor who repudiated his earlier book on Darwinian evolution—mostly due to the discoveries of the information found in DNA—states: "This new realm of molecular genetics (is) where we see the most compelling evidence of design on the Earth" (ibid., p. 221).
Just recently, one of the world's most famous atheists, Professor Antony Flew, admitted he couldn't explain how DNA was created and developed through evolution. He now accepts the need for an intelligent source to have been involved in the making of the DNA code.
"What I think the DNA material has done is show that intelligence must have been involved in getting these extraordinary diverse elements together," he said (quoted by Richard Ostling, "Leading Atheist Now Believes in God," Associated Press report, Dec. 9, 2004).
"Fearfully and wonderfully made"
Although written thousands of years ago, King David's words about our marvelous human bodies still ring true. He wrote: "For You formed my inward parts, You covered me in my mother's womb. I will praise You, for I am fearfully and wonderfully made . . . My frame was not hidden from You, when I was made in secret, and skillfully wrought. . ." (Psalms 139:13-15 Psalms 139:13-15  For you have possessed my reins: you have covered me in my mother's womb.  I will praise you for I am fearfully and wonderfully made: marvelous are your works and that my soul knows right well.  My substance was not hid from you, when I was made in secret, and curiously worked in the lowest parts of the earth.
American King James Version× , emphasis added).
Where does all this leave evolution? Michael Denton, an agnostic scientist, concludes: "Ultimately the Darwinian theory of evolution is no more nor less than the great cosmogenic myth of the twentieth century" (Denton, p. 358).
All of this has enormous implications for our society and culture. Professor Johnson makes this clear when he states: "Every history of the twentieth century lists three thinkers as preeminent in influence: Darwin, Marx and Freud. All three were regarded as 'scientific' (and hence far more reliable than anything 'religious') in their heyday.
"Yet Marx and Freud have fallen, and even their dwindling bands of followers no longer claim that their insights were based on any methodology remotely comparable to that of experimental science. I am convinced that Darwin is next on the block. His fall will be by far the mightiest of the three" (Johnson, p. 113).
Evolution has had its run for almost 150 years in the schools and universities and in the press. But now, with the discovery of what the DNA code is all about, the complexity of the cell, and the fact that information is something vastly different from matter and energy, evolution can no longer dodge the ultimate outcome. The evidence certainly points to a resounding checkmate for evolution! GN
Not So Black and White
Scientists at Penn State continue to explore the genetics of skin color. In a 2017 study published in the journal Science, researchers report their findings of even greater variants in skin color genes among native Africans.
The same appears to be true of Europeans, given that, in 2018, researchers used DNA to reconstruct the face of the first British person, an individual known as the "Cheddar man" who lived 10,000 years ago. The scientists who took part in the reconstruction of the ancient man's face say that he most likely had blue eyes and dark brown skin. While they do not know for sure what he looked like, their findings dispute the idea that Europeans have always had light skin.
Such diversity in skin color genes, says evolutionary geneticist Sarah Tishkoff, the lead author of the 2017 study, likely means that we can't even speak of an African race, much less a white one. As far as people are concerned, the human race is the only one that matters.