Has anyone ever told you that you look like your mom?
Or that you are tall like your grandpa? Maybe your eyes are the exact same color as your dad's.
What makes one person tall and another person short? Why does one person have red hair and
another person has black hair? Whether it's a person, a tiny butterfly, a soaring redwood tree,
or even a giant octopus, every living thing passes along its characteristics to the next generation
through something called genetics. Since the beginning of history, people have been interested
I n why they look the way they do or why some plants and animals are stronger than others.
Ancient animal herders noticed that if they used the strongest animals for breeding, they would
get strong, healthy baby animals. Early farmers used the same methods to improve their crops,
realizing that by planting only the best seeds they could grow stronger, more resilient crops.
Over time, these ancient herders and farmers began to form general ideas about genetic inheritance,
but they did not have a scientific explanation for how these traits were passed along from the
parents to the offspring. No one knew why one crop was so hearty,
or why one sibling might have brown hair while her sister had blonde hair. The amazing story behind
what makes all of these differences possible did not begin to come to light until 1865.
Gregor Mendel, often called the Father of Genetics, was a Roman Catholic monk who lived
in Austria. Mendel believed that all plants and animals passed down traits from parents
to children and he hoped to find a pattern for how this occurs. When Mendel was growing up,
he lived and worked on a farm, so he gained a lot of knowledge and understanding about plants.
In his spare time at the monastery, he began to breed pea plants in the monastery gardens. Through
careful observations of these plants, he noticed that some of the pea plants looked different from
the others. To determine what caused these variances, Mendel performed nearly 29,000
experiments. He concluded that the inheritance of a trait is not a blending of two traits,
as many people had believed previously. He determined that traits are either dominant
or recessive. While working with pea plants, Mendel observed that when a plant received a
dominant trait from one parent and a recessive trait from the other parent, the dominant trait
was always observed in the new plant. Although Gregor Mendel never saw a gene with his own eyes,
he believed that something inside of an organism controlled heredity
or the passing along of certain traits. Today we know that all living things are made of cells,
which are the building blocks of life, and each cell contains within it all of an organism's DNA,
the very thing that Mendel sought to understand. DNA stands for deoxyribonucleic acid.
This is the chemical that makes up your genes and contains the information that
produces all of the traits that physically make you who you are. Every living thing on Earth,
from the tiniest bacteria to the tallest tree, has DNA inside of it storing its genetic information.
Since the time of Mendel and his experiments, scientists have discovered that genetic mutations
or changes in DNA can happen when an error occurs in an organism while copying the DNA
being passed down, and these mutations can be passed from parent to offspring.
Some genetic mutations are helpful, such as the mutation that allows some people to have super
sensitive taste buds or the genetic variation that gives Olympic sprinters their super speed.
However, some mutations can be detrimental. Consider this albino squirrel. Albinism
is a genetic mutation that reduces the amount of melanin a body produces.
Melanin controls the color of the skin, hair, and eyes. This mutation is harmful to the squirrel
because it cannot blend in with its surroundings and is therefore easily seen by predators.
This hairless rat also has a harmful genetic mutation, one that makes it so it can't grow fur.
Hair is an important trait for both humans and animals. Animals rely on their hair for warmth,
protection, and camouflage. Hairless animals have a hard time keeping warm,
which reduces their chance of survival.
Cystic fibrosis is a genetic disorder in humans that mostly affects the lungs. In this disorder,
the cells that line a person's lungs don't work properly.
This causes the lungs to fill up and clog with thick, sticky mucus. People with cystic fibrosis
have difficulty breathing and often experience chronic lung infections.
Sickle cell anemia is an inherited red blood cell disorder. People with sickle cell anemia
don't have enough healthy red blood cells to carry oxygen throughout their bodies.
Normal red blood cells are flexible and round, allowing them to easily move through blood
vessels. Sickle cells are shaped like crescent moons. They are firm, sticky cells that can get
stuck in small blood vessels, slowing down blood flow and oxygen throughout the body.
Interestingly though, people who carry the sickle cell mutation
are more resistant to malaria, an often deadly parasitic infection.
There are also some genetic mutations that are beneficial. In a small town in Italy, a genetic
mutation was identified that protects its carriers from developing atherosclerosis, the buildup of
fatty deposits in the blood vessels of humans which causes cardiac disease and heart attacks.
And in 2008, scientists discovered a genetic mutation that keeps people who are at high risk
of developing type 2 diabetes from actually having the disorder.
Learning about dominant and recessive genetic traits as well as genetic mutations
is a fascinating study that has been captivating doctors and scientists since Gregor Mendel's
pioneering work with plants. Another group of people who study genetics is genealogists or
people who study family history. Certain genetic traits have been passed through families for
centuries. Genetic traits have even been used to solve crimes through DNA evidence. Surely,
in the future, even more amazing discoveries will be made using the science of genetics.