Genetics: A Brief Glance

I’ve written oodles about my own personal genetic profile – and some of the ways genetics factor into my health – but not so much about the inner workings and terminology of genetics.

Well, today, I’m going to do just that. We’ll take a brief look at some of the terminology used to reference and describe the engineering marvel that is deoxyribonucleic acid….or…DNA. 🙂


 Alleles

allele

[uhleel

nounGenetics.

1.

any of several forms of a gene, usually arising through mutation, that are responsible for hereditary variation.
Taken from www.dictionary.com

According to sciencedaily.com:

An allele is a viable DNA (deoxyribonucleic acid) coding that occupies a given locus (position) on a chromosome.

AND:

An allele is an alternative form of a gene (in diploids, one member of a pair) that is located at a specific position on a specific chromosome.

(A diploid cell is a cell that contains two complete sets of chromosomes, one from each parent [so any human will have diploid cells].)

In other words, an allele is a specific genetic variant that it is possible for you to have. For any given location on the genetic code, there may be multiple alleles (variants, mutations, alternative forms) that you could inherit from your parents.


Gene Methylation

Certain methyl groups can bind to DNA strands, altering the expression of a gene, without actually altering the DNA code.

A methyl group consists of three hydrogen atoms bonded to one carbon atom, so the chemical structure will look something like CH3 or CH+3.


Epigenetics

According to whatisepigenetics.com:

Epigenetics, as a simplified definition, is the study of biological mechanisms that will switch genes on and off.

And according to lindau-nobel.org:

Epigenetics refers to the meta-level of genetic regulation. Under the influence of external factors, epigenetic mechanisms regulate which genes are turned on and off. This helps our fixed genetic material to be more flexible. At the biochemical micro level, epigenetic regulators are responsible for how closely packed individual genomic regions are and therefore how accessible or not they are. This works by small adhered or detached chemical groups. The resulting marking of the genome is read by specialised enzymes that then cause the switching on or off of the genes.

In other words, while our genotype (genetic constitution) is relatively fixed (except when we develop mutations), the expression of those fixed genes can potentially be switched on or off like a light. Epigenetics is the study of this process.


Mutagens

Mutagens are agents, such as radiation and certain chemicals, that can cause mutations.

Mutagens may include substances and light sources such as bromine, asbestos, UV light, Bisphenol A (BPA), some hair dyes, formaldehyde (a disinfectant, preservative of museum specimens of animals and organs, fixative, a crease/crush resistance aid and a flame resistance aid in automobile exhausts, and found in adhesives), fumes (released by outdoor burning, defective wood-burning fireplaces, coal furnaces), hydrogen peroxide, phthalates (plasticizers used in some cosmetics and nail polish), sodium bisulfite (a preservative in fruit juices, wine, and dried fruits), sodium nitrite (a common preservative of cold cuts, fish and cheese, which can be converted in the body into nitrosamines [carcinogenic compounds]), and trichloroethylene (may be present in dry-cleaning agents, degreasing fluids, paints, varnish, and food-processing solvents).

For a longer list of mutagens, check out this site.


Recessive and Dominant Traits

A recessive trait is only expressed when the child receives that trait from both parents.

If only one recessive allele is present, then the recessive trait will not be expressed.

Dominant traits, on the other hand, need only be inherited from one of the parents in order to express themselves.

Check out this page for some examples of dominant vs. recessive traits.

A great example of recessive vs. dominant traits is that involving blood type. “A” is a dominant trait, “B” is also dominant, and “O” is recessive, so:

AA (A from each parent) = type A blood

AO (A from one parent, O from the other) = type A (because O is recessive)

AB = type AB (A and B are codominant)

BB = type B

BO = type B

OO = type O (Since the genetic allele for O blood is recessive, this is the only genetic combination that will result in type O. It must be inherited from both parents.)

You can see, though, how two parents – one with type B blood and one with type A blood – could have a child with type O blood, if they each had a hidden recessive (unexpressed) O trait that they both happen to pass down to their child.

AO x BO = four possible combinations:

AB

AO

BO

OO

DNA
Photo credit: publicdomainpictures.net

So that’s a brief look at genetics. But I’ve barely scratched the surface of this highly complex world. For more information, check out these articles:

 

What is a Gene Mutation and How Do Mutations Occur?

Study of Holocaust Survivors Finds Trauma Passed On to Children’s Genes

 

Thanks for reading! 🙂


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3 thoughts on “Genetics: A Brief Glance

  1. Pingback: Lifestyle Changes To Overcome Depression - Get Well Forever

  2. Pingback: Genetics: A Brief Glance — Reflection Cube – Site Title

  3. Pingback: My Journey to Recovery: An Update – Reflection Cube

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