Punnet Squares/ Genes
I have a question for the person reading this. “Why is diarrhea hereditary? Because it runs through our jeans!” I know that joke is disgusting but it is true. All of us as humans have genes that are passed down from our parents that make up our physical traits. The type of genes I am talking about is not the ones you can buy at American Eagle, those are JEANS. According to the Webster Dictionary, the gene I am talking about is “a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristics of the offsprings.”
So how exactly how does this happen? Well people usually have two copies of chromosomes (thread like structure made or proteins and a single molecule). One copy is inherited from your mother by her egg. The other copy is inherited by your father by his sperm. A sperm and an egg each contain one set of 23 chromosomes. When the egg is fertilized by the sperm, two copies of each chromosome are present, creating an embryo (Better Health, 2024). Now an uncomplicated way to visualize this is within a diagram called a punnet square.
The Punnett square is a square diagram (pretty obvious that it is a square) that is used to predict the genotypes (the genetic makeup of an organism) of a particular cross or breeding experiment. This allows you to see the crossing between two parents and what the outcomes of their offsprings will most likely be. For example, if you were to cross a heterozygous (meaning different) dominate allele and a homozygous (meaning the same) recessive allele you would be able to predict that 50% of the offspring would have the dominate trait and the other 50% would have the recessive trait. So, what exactly is a trait? According to the National Human Genome Research Institute, a trait is a specific characteristic of an individual. This could be qualitative such as eye color or quantitative such as height or blood pressure.
To break down traits even more, there are dominate and recessive traits. Dominate traits are those that are inherited and unchanged in a hybridization. Recessive traits are those that disappear in the offspring of a hybridization. Dominate traits tend to be, well more dominate, in the passing of traits. For instance, brown hair could be considered a dominant tray whereas red hair would most likely be considered a recessive trait. The dominate trait is typically illustrated by a capital letter within the Punnett square. On the contrary, a recessive trait is typically illustrated by a lower-case letter. The physical traits that you can see such as eye color, hair color, the shape of someone’s nose, skin color, height, etc. are what we call the phenotype. The phenotype is defined as the observable physical properties of an organism. So, the saying “I got it from my mama,” is not just a phrase we say for fun. It is most of the time used in a sarcastic way, but it is true. The pretty blue eyes that get all the compliments were passed down from someone and inherited by the person receiving the compliment.
References
Trait. (n.d.). Retrieved October 17, 2024, from https://www.genome.gov/genetics-glossary/Trait
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