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Mikayla S.
May 83 min read

Genes! The Influence of Our Inheritable Traits

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Introduction

"It's in your genes!" is a common saying that we've all heard several times before, often used to signify an innate characteristic about yourself. But how exactly do genes influence our actions and behaviors? And better yet, what exactly are genes to begin with?


Terms Related to Genes

There are many terms associated with genetic code and what is used to describe traits. The following are definitions that you may find helpful in understanding genetics and its related concepts.

  • Gene: a segment of DNA that contains information that influences a variety of characteristics [1]

  • Allele: a possible variation of a gene that has two or more potential alternate forms [2]

  • Dominant: when a trait or disease is observable with the possession of one particular allele for a given gene [1]

  • Recessive: when a trait of disease is only observable with the possession of two particular alleles for a given gene [1]

  • Carrier: An individual who carries an allele associated with a recessive trait or disease [3]

  • Genotype: an individual's genetic makeup, particularly regarding the alleles they possess [1,2]

  • Phenotype: an individual's physical and observable features that develop as a result of the interactions of genes and environment [1]

  • Genetics: individual genes are studied, particularly from the point of view of inheritance [4]

  • Genomics: the entirety of an individual's genetic material is studied [1]

  • Epigenetics: Modifications that impact phenotype but don't alter the DNA itself are studied [1,2]


How Traits Are Inherited

Genes are segments of DNA that are used to ultimately build proteins, which are the physical product of the information encoded by genes. DNA is the infamous molecule used by all organisms to store hereditary information and is organized into chromosomes. [5] The number of chromosomes an organism has varies between species, but humans typically have a total of 46 chromosomes that form 23 pairs. The last pair of chromosomes is known as the sex chromosomes and will determine if an individual's sex at birth is female or male. People typically will inherit half of their chromosomes from their mother and the other half from their father. [6]


Expression and Observation of Genes

The central dogma is used to explain the process of going from genes to proteins. It starts with double-stranded DNA being transcribed into the single-stranded messenger RNA (mRNA). mRNA then translates the information to build proteins, the final product of this process. [7,8] Proteins then are used to fulfill a variety of functions throughout the cell that enable an organism to live. Non-coding RNAs, or RNA molecules that aren't used to create proteins, are also produced and utilized by the cell for other purposes. [9]


Gene expression will vary between the various cell types and environments found within the body. In addition to this, it is also a highly regulated process. This genetic expression impacts when, where (in the body), and how much corresponding RNA molecules or proteins are produced. [9] Molecules known as transcriptional factors are key in regulating expression. It is important to note that not all genes will be expressed in every cell type. In fact, it is typical that only a small subset of the around 20,000 genes in the human genome will be active in any given cell.


Genetic expression can be observed through either the resulting visible traits (i.e. the phenotype) or by how functional the corresponding proteins are. [9] This allows for the connection of a phenotype to a genotype.


Genetics and Genomics in Regards to Health

As time has gone on, the role that an individual's genetic information has played a role with ever-increasing importance. Genetics, or the study of how individual genes are inherited, is especially prevalent in diagnosing and treating diseases caused by a single gene. Examples of such conditions include cystic fibrosis, sickle cell anemia, and Turner Syndrome, among others. [4,10]


Genomics is a more encompassing view of how an individual's entire genome, or the entirety of their genetic information, interacts with their environment. It is focused more on studying complex diseases, such as diabetes and cancers, that arise from a combination of genetic predispositions and environmental factors. Genomics is also important in understanding how individuals with different lifestyles and environments can display vastly different responses to similar stimuli. [4]


Because genes are inheritable, it is important now more than ever for individuals to be familiar with family medical history. Familiarity with one's family history can allow for early detection and treatment of genes that cause diseases or predispose individuals to conditions such as cancer. This allows for precise medical care and family planning to occur when appropriate. [4,10]


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