Genetics is one of the most fascinating branches of biology.
Genetics is the scientific study of genes, genetic variation, and heredity.
Wrapped tightly within thread-like cellular structures called chromosomes, each gene of your body has a specific role to play. They are essentially a set of instructions.
Perhaps the biggest role they play is in the inheritance of physical traits. There are a number of genetic traits that get passed from parent to offspring.
What Are Genes?
The study of genetics is complex. Scientists believe that the human body contains roughly 20,000 different genes. The advent of genetics and genes began with the theory of evolution in the mid to late 19th century.
This area of study continued to advance into the 20th century as new theories and technologies offered more insight into this complex area of biology.
Today, the Human Genome Project continues the endeavor by seeking to map the human genome (sets of genes) — that effort is still ongoing. This research has implications for treating genetic disorders and diseases.
While the task to definitively understand genetics is daunting, we do understand one of their primary roles — passing on physical traits.
Genes are the basic units of physical inheritance, and they contain information that helps determine how we look, e.g., our physical characteristics.
A Closer Look
Genes are housed within our chromosomes inside the nucleus of nearly every cell. The nucleus directs and regulates cellular activity.
Chromosomes are composed of both proteins and deoxyribonucleic acid (DNA). It is the DNA in which the genes are encoded. Humans have 23 pairs of chromosomes — 22 autosomes and one pair of sex chromosomes (XX for females, XY for males).
Telomeres, DNA-protein structures, are found at the end of linear chromosomes and serve as protective caps.
Telomeres shorten every time the cells divide, which means some DNA is lost. Eventually, as it shortens, the telomere DNA is lost and the cell is unable to replicate. This has led researchers to believe there is a link between aging and telomere length.
Genes and DNA
Genes are encoded on DNA strands. DNA is composed of structural components called nucleotides. These serve as the building blocks and have a base (either adenine, thymine, guanine, or cytosine), a phosphoric acid, and a sugar molecule.
The two strands of DNA molecules are held together by bonds between these nucleotide bases, getting their double helix shape. Only a portion of a single DNA molecule corresponds to a single gene.
Inheritance and Genetics Traits
The research into the study and definitive role of genetics is continual at this point. But, research has shown us the important role of genetics in terms of heredity.
Like all living organisms, we inherit traits from our parents. Inheritance refers to the process by which genetic information is passed from parent to offspring.
We received one set of genes from each of our parents. In terms of genetics, a trait refers to a specific characteristic of an organism. These are called genetic traits.
A genotype is our collection of genes or version of DNA sequence. A phenotype is the actual observable traits (e.g., eye color), determined by our genotype. An allele refers to a variant form of a gene.
Let’s take a look at the most common genetic traits.
Eye Color
Eye color is one of the most observable genetic traits. Brown eyes tend to be the most dominant allele type. So, if one parent has blue eyes while the other has brown, you’re more likely to end up with brown eyes. However, if one of your grandparents had blue eyes that trait may be passed on to you. This would be known as a recessive trait.
Hair Color
Hair color can also be inherited from one or both parents. The way genes work, you could even have a different color than both of them — an inherited trait from a grandparent. Hair type and hairline shape are also inherited genes.
Height
Hereditary factors also determine height. Typically, children end up being an average of their parent’s height, but that is not always the case. Scientists believe that one’s lifestyle and environment, including nutrition, also plays a major role.
Bone Structure
Believe it or not, bone structure is a genetic trait. This includes facial structure. For example, if a parent has high cheek bones there’s a good chance that trait may be passed down to children and even grandchildren.
Freckles and Dimples
Freckles are small spots of skin pigmentation on the face, more common in fair-skinned people and those with red hair (another genetic trait). The MCR1 gene controls this phenomenon — parents with freckles have kids with freckles. Another highly heritable trait is dimples.
Handedness
Researchers have determined that handedness might also have a genetic link. For example, the LRRTM1 gene has been associated with left-handedness. Perhaps that is why left-handedness tends to “run in the family.”
More Inherited Traits
The list of inherited traits could go on and on, but here are some of the more commonly known traits:
- Tongue rolling
- Widow’s peak
- Fraternal twins
- Chin cleft
- Red/green colorblindness
- Hand clasping
- Curly hair
- Earlobe attachment
Conclusion
Genetics is the study of genes and genetic variations. While genetics remains a complex branch of biology, our understanding of it grows each year as research and technologies advance.
One of the key roles of genetics is in the area of heredity — the characteristic and traits we inherit from our parents. Hair color, eye color, our height, and even our handedness can be traced to genetic factors.
While we might not understand all that genetics entail, we do know that they help make us who we are.
Sources:
What is the Human Genome Project? | Genome.gov
