A More In-depth Look at DNA

We have seen that cells are the fundamental working units of every living system. All the instructions needed to direct their activities are contained within the chemical DNA stored in every cell.

DNA from all organisms is made up of the same chemical and physical components. The DNA sequence is the particular side-by-side arrangement of bases (DNA “letters”) along the DNA strand (e.g., ATTCCGGA). This order spells out the exact instructions required to create a particular organism with its own unique traits.

The genome is an organism’s complete set of DNA. Genomes vary widely in size: the smallest known genome for a free-living organism (a bacterium) contains about 600,000 DNA base pairs, while human and mouse genomes have some three billion. Except for mature red blood cells, all human cells contain a complete genome.

DNA in the human genome is arranged into 23 pairs of chromosomes – physically separated molecules that range in length from about 50 million to 250 million base pairs.  Each chromosome contains many genes, the basic physical and functional units of heredity. Genes are specific sequences of DNA base pairs that encode instructions on how to make proteins. Genes comprise only a small percentage of the human genome (close to two percent); the remainder consists of non-coding DNA (also referred to as junk-DNA), whose functions may include providing chromosomal structural integrity and regulating where, when, and in what quantity proteins are made. The human genome is estimated to contain 20,000 – 25,000 genes.

At the end of the chromosome there is a highly repetitive section of DNA called a telomere. We will discuss telomeres in detail later[15] as remarkable evidence for God’s inspiration of the Bible.

Junk DNA, Evidence for Evolution or Design?

In molecular biology non-coding DNA, or junk DNA, is a collective label for the portions of the DNA sequence of a chromosome for which no function has yet been identified. Currently of the human genome, about 97% of all DNA has been designated as “junk.”

A Further Look at DNA

Evolutionists initially considered the presence of junk DNA as a strong argument for the random process of evolution and against involvement of an intelligent Creator: “Why would a perfect God create DNA which is primarily composed of useless, non-functional sections?”

According to one evolutionary explanation, the sections of junk DNA consist either of randomly produced sequences that are non-functional or are leftovers from ancestor DNA no longer used. Another evolutionary claim is that the junk DNA is like a parasite – also called selfish DNA, in because it consists of DNA that preferentially replicated more efficiently than coding DNA.

As knowledge grows, numerous studies find more actual use of large sections of what was previously considered junk material.  First it has become clear, using statistical techniques, that the non-coding DNA is actually highly uniform and patterned, and by far not just random. Second, more definitive studies have shown that non-coding DNA provides structure to DNA so it can perform functions impossible without some form of structure. Third, it has become evident that the non-coding DNA sections play a role as enhancers for transcription of certain genes. Fourth, the existence of so called pseudo-genes (copies of regular genes in the non-coding sections) has proved to play an important role in the proper working of the corresponding regular genes.

Lastly, it now appears that sections of the non-coding DNA play a role as molecular switches to tell genes when and where to turn on and off. Dr C. Owen Lovejoy in the earlier mentioned Time Magazine article[16]: “Take the genes involved in creating the hand, the penis and the vertebrae. These share some of the same structural genes…. It is like having the blueprints for two different brick houses. The bricks are the same, but the results are very different.” The article goes on to say: “Those molecular switches lie in the non-coding regions of the genome – once known dismissively as junk DNA, but lately rechristened the dark matter of the genome.”

The “evolution” of junk-DNA from “junk” to “dark matter” illustrates that non-coding DNA is not evolutionary left-over material and that the science of genetics still has a long way to go to understand fully the purpose and working of DNA in the cell replication process.

Haeckel's Embryo's