The Unseen Genes.
Pluripotency is the capacity of stem cells to remain undifferentiated. This is mediated by three proteins. As this gene into protein diagram examines, the relation among these molecules is far more integrated than it had first appeared. Consider the role of stem cells and what accounts for the undifferentiated stem cell. Geneticists call this power of the undifferentiated cell pluripotency.
There exist three identified proteins that suppress the other genes in the nuclei of stem cell's from expressing their proteins and thus to direct the stem cell to differentiate or become a bone cell or a neuron. These newly discovered proteins are called OCT4, SOX2, NANOG. Each o them bind to genes and inhibit the expression of those genes, thus this state of pluripotency is retained. When these proteins are not present other proteins are generated that direct the stem cell to morph into a specialized cell.
So what do we know of the relation among genes on a chromosome --such as pictures here the alleles of chromosome 20? What we do know is that just a small part of the genome is ever expressed. We also are beginning to realize that DNA and the proteins that genes code for are far from the definitive ingredients in replication of the genetic code. Despite how much we have learned and have yet to learn, a pattern is emerging.
This pattern deals with the suppression of genes (the genotype remains unexpressed as a phenotype) the selection pressure on the entire genome, and the curiously essential role of RNA in the process of replication. Replication refers to how the DNA divides during cell division, or in the manufacture of proteins. DNA requires proteins and RNA for a complete process of duplication to occur.
Pictured in its chemically precise molecular constituents of carbon, nitrogen, sulphur and phosphorus atoms, the DNA molecule on the right holds teh base pair sequences that code for a sequence of amino acids. The precise order of these amino acids determine the sort of protein the strand may become. But DNA alone cannot create the amino acid chain, and those amino acid chains must be assembled into a protein. That protein will not function if it is not folded into a proper shape, much like a bad key will fail to open a paricular lock.
RNA plays a pivotal role in inwinding, translating, matching, editing and reassembing the DNA code when proteins are manufactured in the cell based on the (genotype) codes translated by RNA molecules from the DNA template. Genes in this way can be built into proteins by the RNA and specialized assembly structures in the cells. Without RNA, the DNA remains a storeroom, a sort of potential wharehouse for how to arrange a protein, but not the full complement of ingredients needed for a functioning protein.
In the case of the proteins OCT4, SOX2, and NANOG they bind to certain genes that would otherwise change a stem cell into a specialized cell. These proteins are not the only means of suppressing a gene from expressing itself as a protein (called the phenotype). There are two other means of inhibiting a stretch of DNA that codes for the amino acids in a protein from being expressed. One involves methylated chemicals and the other involves RNAi. The latter is a variant of the quite variable RNA molecule, while the former is a methyl compound containing protein that blocks a stretch of DNA from being transcribed by another kind of RNA, called RNA polymerase.
Despite the complexity of supressing gene expression in cells, the process by which DNA is utilized by RNA in the cell to generate the needed proteins for life to persist suggests an underlying partnership. Beyond the RNA and DNA teams that must play together to achieve the desired outcome, proteins are another vital partner in the process of life on a cellular and subcellular scale. At the right is a depiction of RNA polymerase along a DNA chain.
I refer to this relationship among DNA (which gets all the attention), RNA (which is quite variable in its functions) and proteins with an analogy. In our more familiar realms of experience teh DNA has to be though of as something important, but inert. The RNA is the active ingredient performing several functions or roles. And the protein is the end product of the team's collaboration and some proteins can affect the DNA. This to me sound like a performance, even a dance.
If the DNA, RNA, protein trio is thought of as a dance performance, one may consider the DNA as the choreography, the RNA as the choreographer and the protein as the performer who brings to life the script under the direction of the choreographer. All life then is the precise or particular performance of these components of an intricate dance. Each part is necessary, without each the process is truncated, if not terminated in its entirety and life is modified by the loss of that particular function which the protein enables a cell to operate. Much like a trio of musicians the particular performance, the sounds we hear, or the dance we see depends on the contributions of each, the timing and the combination of each participant.
Genetics is more than meets the eye, or in the mind's eye it includes many "unseen genes."