Epigenetics is the study of how cells control gene activity without changing the DNA sequence. “Epi-“ means on or above in Greek, and “epigenetic” describes factors beyond the genetic code. Epigenetic changes are modifications to DNA that regulate whether genes are turned on or off.

Aristotle

Epigenetics is a real and important part of biology, but due to predictable quackery, it is threatening to become the new quantum. All of your cells contain all of your 22,000 genes, but not all of them need to be active all the time.

Some people have had a stem cell transplant using their own stem cells. This type of transplant does not have any impact on DNA and DNA test results. Organ transplants also do not appear to impact DNA results, even though the organ has come from a different person whose DNA differs from you.

Stem cells sabotage their own DNA to produce new tissues, new study suggests. Summary: Stem cells intentionally cut and then repair their own DNA as a mechanism of activating genes that promote the development of new tissues, according to new research. Human cells contain 46 strands of DNA that code for all our genes.

All of the cells within a complex multicellular organism such as a human being contain the same DNA; however, the body of such an organism is clearly composed of many different types of cells. The answer lies in the way each cell deploys its genome.

Chimera: In medicine, a person composed of two genetically distinct types of cells. Human chimeras were first discovered with the advent of blood typing when it was found that some people had more than one blood type. About 8% of non-identical twin pairs are chimeras.

DNA is a linear molecule composed of four types of smaller chemical molecules called nucleotide bases: adenine (A), cytosine (C), guanine (G), and thymine (T). The order of these bases is called the DNA sequence.

Each cell expresses, or turns on, only a fraction of its genes at any given time. The rest of the genes are repressed, or turned off. The process of turning genes on and off is known as gene regulation.

When a gene is turned off, it no longer provides the directions for making proteins. This means that the proteins needed to fulfill a particular job — say, tolerate lactase — aren’t produced. Think about following driving directions on a GPS device in your car.

An active lifestyle will awaken the best genes. All you need to do is indulge in some sport or physical activity such as dancing or running on a regular basis. Your body will activate genes needed to support those activities over time. The impact has a net positive on your health, mind and productivity.

How do these cues help a cell “decide” what genes to express? Cells don’t make decisions in the sense that you or I would. Instead, they have molecular pathways that convert information – such as the binding of a chemical signal to its receptor – into a change in gene expression.

An international research effort called the Human Genome Project, which worked to determine the sequence of the human genome and identify the genes that it contains, estimated that humans have between 20,000 and 25,000 genes. Every person has two copies of each gene, one inherited from each parent.

We find that in individual cells, most protein-coding genes are expressed at levels between 1 and ∼50 copies per cell. The distribution suggests a roughly equal number of genes at each level except for a larger group of transcripts with fractional transcript-per-cell values.