Study of Sexual Parasite Reveals Function for Junk DNA
Cell biologists believe that in addition to housing genetic information, DNA plays a skeletal role in the nucleus; the more DNA in the nucleus, the greater the size of this organelle because of the volume occupied by DNA.
The ratio of the nuclear volume to cell volume is a critical parameter. To accommodate reasonable growth rates, large cells need to have a large nucleus.
Evidence increasingly indicates that noncoding DNA may be a key component of the nucleoskeleton and the chief determinant of nuclear volume and, ultimately, cell size.
Evolutionary biologists have traditionally thought of noncoding DNA as junk, the product of random biochemical events. They consider the existence of junk DNA as one of the most potent pieces of evidence for biological evolution. According to this view, junk DNA results when undirected biochemical processes and random chemical and physical events transform a functional DNA segment into a useless molecular artifact. Junk pieces of DNA remain part of an organism’s genome solely because of its attachment to functional DNA. In this way, junk DNA persists from generation to generation. Skeptics ask, “Why would a Creator purposely introduce nonfunctional, junk DNA into the genomes of organisms?”
Yet if noncoding DNA dictates nuclear volume then it’s not junk at all.
A recent study published in the January 12, 2007 issue of Science provides additional evidence for the nucleoskeletal role of noncoding DNA. This DNA appears to play an indirect but important role in the life cycle of the sexually transmitted human microbial pathogen Trichomonas vaginalis. This single-celled protist has a massive genome due to an inordinate amount of noncoding DNA. The large genome size explains the large cell size of T. vaginalis. This cell’s girth, and hence large surface area, benefits T. vaginalis by providing more contact sites for this microbe to attach to the vaginal wall during infections. Large cell size also prevents it from being eaten by the body’s white blood cells. It looks as if noncoding DNA plays a critical role in T. vaginalis.
Studies like these and others help explain why the Creator purposely introduced noncoding DNA into the genomes of organisms.
For a more detailed discussion of how junk DNA fits into RTB’s creation model, see Who Was Adam?