THOUGHT! I have been doing a little research and found some interesting stuff. I thought I would share it and see if it sparks anymore debate/discussion on the Patternless genetic possibilities. It is interesting to say the least.
Epigenetics
There is far more to genetics than the sequence of building blocks in the DNA molecules that make up our genes and chromosomes. The "more" is known as epigenetics.
What is epigenetics?
Epigenetics, literally "on" genes, refers to all modifications to genes other than changes in the DNA sequence itself. Epigenetic modifications include addition of molecules, like methyl groups, to the DNA backbone. Adding these groups changes the appearance and structure of DNA, altering how a gene can interact with important interpreting (transcribing) molecules in the cell's nucleus.
How do epigenetic modifications affect genes?
Genes carry the blueprints to make proteins in the cell. The DNA sequence of a gene is transcribed into RNA, which is then translated into the sequence of a protein. Every cell in the body has the same genetic information; what makes cells, tissues and organs different is that different sets of genes are turned on or expressed.
Because they change how genes can interact with the cell's transcribing machinery, epigenetic modifications, or "marks," generally turn genes on or off, allowing or preventing the gene from being used to make a protein. On the other hand, mutations and bigger changes in the DNA sequence (like insertions or deletions) change not only the sequence of the DNA and RNA, but may affect the sequence of the protein as well. (Mutations in the sequence can prevent a gene from being recognized, amounting to its being turned off, but only if the mutations affect specific regions of the DNA.)
Epistasis
Some genes mask the expression of other genes just as a fully dominant allele masks the expression of its recessive counterpart. A gene that masks the phenotypic effect of another gene is called an epistatic gene; the gene it subordinates is the hypostatic gene. The gene for albinism in humans is an epistatic gene. It is not part of the interacting skin-color genes. Rather, its dominant allele is necessary for the development of any skin pigment, and its recessive homozygous state results in the albino condition, regardless of how many other pigment genes may be present. Because of the effects of an epistatic gene, some individuals who inherit the dominant, disease-causing gene show only partial symptoms of the disease. Some, in fact, may show no expression of the disease-causing gene, a condition referred to as nonpenetrance. The individual in whom such a nonpenetrant mutant gene exists will be phenotypically normal but still capable of passing the deleterious gene on to offspring, who may exhibit the full-blown mutation.
Chromosomal crossover refers to recombination between the paired chromosomes inherited from each of one's parents, generally occurring during meiosis. During prophase I the four available chromatids are in tight formation with one another. While in this formation, homologous sites on two chromatids can mesh with one another, and may exchange genetic information.
Because recombination can occur with small probability at any location along chromosome, the frequency of recombination between two locations depends on their distance. Therefore, for genes sufficiently distant on the same chromosome the amount of crossover is high enough to destroy the correlation between alleles.
Genetic recombination is the process by which a strand of genetic material (usually DNA; but can also be RNA) is broken and then joined to a different DNA molecule. In eukaryotes recombination commonly occurs during meiosis as chromosomal crossover between paired chromosomes. This process leads to offspring having different combinations of genes from their parents and can produce new chimeric alleles.
Hypervariable genes
When we analyze the sequence of particular genes in a population, it is clear there are subtle differences for some. When an evolutionist finds that a gene has been changed, it is automatically assumed that mutation was involved. However, we have now recognized that some genes are hypervariable in comparison to others. Not all genes are variable. The sequence of housekeeping gene tend to remain constant, but interestingly, the genes involved with interspecies contact seem typically hypervariable.
Hypervariable genes change at a higher rate than the neutral regions between genes. These genes are also not randomly variable. Only a particular region of the gene changes. There is always a conserved and variable portion of the gene. It has also become clear that certain codons within the altered area remain unchanged, and nucleotide substitution show a clear preponderance for transversional changes (AT to TA) rather than transitional.
Although these new alleles were originally thought to be the result of mutation, it is now understood that genetic recombination is involved. A process known as gene conversion is now recognized as being responsible for the changes that our found in many genes, such as those used to make antibodies. The genes are not changing randomly due to errors. There is a cellular machinery that is intentionally changing their sequence to produce adaptive fitness.
Let's here some thoughts!
-----
Ty Hege
Rat Race Solutions
www.ratracesolutions.com
