Dr. Charles Ruark
I understand DNA to be very similar to a computer hard drive. It is often stated that DNA contains instructions in the form of a computer program. I believe this to be somewhat of a misnomer. While it is true that our DNA contains promoters, enhancers, silencers, and insulators in the form of proteins that regulate transcription, there is no comprehensive computer program contained in our DNA. These proteins and their binding sites are usually, but not always, near to the gene that is to be transcribed.
About 1% of our DNA comprises the coding portion. This 1% is known as exonic DNA because it is our exons. Only exons can code for proteins. Although the structural genes containing our exons are sometimes grouped in clusters, most of the time, the structural genes containing our exons are scattered randomly throughout our genome. About 99% is termed noncoding DNA because it does not code for proteins.
Junk DNA?
In the past, scientists have referred to noncoding DNA as junk DNA. However, this term has faded in popularity (though some still use it) and will not be used in this article. Introns comprise about 30% of the non-coding portion of our DNA. Introns act as spacers between the exons of a structural DNA gene. If a gene does not contain introns, it cannot be transcribed. During transcription the introns are removed, and the exons are spliced together to create the mRNA that is decoded at the ribosome.
On average a DNA structural gene codes for about three proteins. Human genomes contain about 21,000 structural genes. Structural DNA genes comprise about 23% of our genome and contain our exons (1%) and introns (22%). Introns can also be found in pseudogenes; however, most pseudogenes do not contain them. Pseudogenes are similar to functional, structural DNA genes but are damaged and inactive. They are incapable of producing proteins and comprise about 6% of our genome for about 20,000 pseudogenes.
RNA
RNA genes comprise about 1% of our genome. These genes are responsible for producing functional RNA. Examples of which are transfer RNA (tRNA) and ribosomal RNA (rRNA). RNA genes contain introns (6%). The term RNA gene is a bit of a misnomer because all genes, including RNA genes, are composed of DNA. When these are transcribed, they remain as RNA, either tRNA or rRNA, or other functional noncoding RNAs. During transcription, the introns are removed, and the RNA forming the RNA products are spliced together.
Protein-coding structural genes almost never have copies, i.e., duplicates. Voet’s proposed reason for this states that possessing a maternal gene and a paternal gene is adequate for producing adequate amounts of mRNA to produce most proteins. However, wouldn’t it be nice for us humans to have multiple copies so that in the event of a harmful mutation, we might have several functional genes to spare for each protein?
The DNA Composition of our Genome
So, let’s do some addition. So far we have accounted for introns (30%), exons (1%), RNA genes (1%) and pseudogenes minus their introns (1%) or about 33%. This leaves about 67% of our DNA unaccounted for. At least 59% or more of these 67% are viral in origin, and about 9% are unknown.
There are other ways to break down the DNA composition of our genome. For example, on p.933 of Voet’s Fundamentals of Biochemistry 5th Edition, it is stated that retrotransposons account for nearly 67% of the human genome, essentially accounting for the 9% that remains unknown, according to another source. It is also interesting that of the 1% of our genome that codes for protein, only 60% has a known function. Fully 40% contains code, but the exact protein or reason for its existence is, as of Voet’s 5th Edition, still unknown. We hope you can appreciate that these percentages are only estimates.
Damage and Corruption to Our DNA
Suffice it to say that a huge portion of our genome shows evidence of damage and corruption. Evolutionists maintain that this is the result of billions of years of evolution. However, we believe the corruption took place in the Garden of Eden when Adam and Eve ate the fruit of the tree they were commanded not to even touch lest it kill them.
In Genesis 3:14, Jesus not only placed a curse on the serpent, but on all the beasts. The cattle seem to be singled out but it is not clear how important this is. The important point is that the higher animals are cursed to the same degree as humanity. We believe this toxin spread to them, and as a result, they suffer the penalty of sin in their bodies to the same degree as humanity.
As you descend downward in the level of complexity of Life until bacteria are reached, the effects of this toxin become nil. Bacteria don’t care about this toxin. They thrive on mutation and enjoy unbridled multiplication. Given a suitable culture medium, an E. Coli bacterium would quickly multiply to the size of the Milky Way galaxy and still be indistinguishable from the original bacteria. Their original genome would be intact, albeit with some harmless mutations.
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