Thank you for making me so wonderfully complex!
Your workmanship is marvelous—how well I know it.
Your workmanship is marvelous—how well I know it.
Psalm 139:14 NLT
"The field of epigenetics is one of the most exciting and rapidly
expanding scientific research areas in the study of the genome and how
it responds adaptively in organisms.
The term epigenetics is derived
from genetics plus the Greek prefix epi, which means “on top of”
or “in addition to.” In other words, it’s an additional type of genomic
language that overlays the DNA code that controls how genes are switched
on or off.
Epigenetic changes in the genome are modulated dynamically according to
sensory input that the body detects from its physical surroundings,
signaling molecules it receives from other creatures (e.g., gut
microbes), diet, and even stress. In fact, many epigenetic changes can
be heritable and affect traits passed along to children and
grandchildren.
Two different systems can epigenetically modify an organism’s
chromosomes.
The first and most easily studied system is known as
cytosine 
methylation, which is the addition of chemical methyl groups to
the actual DNA base molecules or nucleotide letters.
The second system
is the modification of proteins called histones that integrate with the
DNA and allow it to be packaged and spatially structured in different
ways.
The DNA code comprises the ordered sequence of the nucleotide 
letters A (adenine), C (cytosine), T (tyrosine), and G (guanine).
Epigenetic modification of the actual DNA molecule occurs specifically
on the cytosines by the addition of small epigenetic tags called methyl
groups—hence the term cytosine methylation.
The presence of these methyl tags in the DNA molecule plays a major role
in the way that genes are expressed, i.e., turned off and on.
In general, when the control regions of genes known as promoters are
heavily methylated, the gene is turned down like an adjustable light
switch being dimmed.
In addition, many other switches called enhancer
elements that are around the genome outside of genes can also become
methylated, which regulates the level of gene activity as well.
The addition of methyl tags in the writing process is done by enzymes called DNA methyltransferases.
In humans and other mammals, scientists have discovered at least three
different methyltransferases that function as writers.
The erasing
function of methyl tags is done by enzymes called demethylases, which
remove methylcytosines and replace them with regular cytosines using
specialized enzymatic machinery.
Second, complex cellular machinery and surveillance systems must
interpret the huge diversity of epigenetic tags not only according to
the creature’s environment but also based on the type of cell and tissue
in which the chromatin is located.
Third, for the complete epigenetic
system to be passed along during cell growth and to the next generation,
there exists yet another separate and necessary system that copies the
chromatin profile when the cells are replicated or sperm and egg are
produced for reproduction.
The evolutionary story of random mutations and natural selection can’t
account for DNA’s exquisitely engineered systems. Only our Creator can."
ICR