by Benigra, Paden, and Romero (2020)
BLOODLINE GENETICS
................Genetics is the study of genes and traits, and how varied they are for each individual. It also studies how these genes are passed on from generation to generation. For this particular instance, we are taking a closer look into how blood type varies per person and how it is passed down to the children.
................First, we must realize the basics of genetics which is the process of cell division. There are two types: mitosis and meiosis. Mitosis deals with the division of somatic (non-reproductive) cells. It is responsible for the growth and regeneration of an organism. On the other hand, meiosis is the division of sperm and egg cells that carry the alleles for the offspring. This process produces the gametes needed during sexual reproduction. In order to see how blood type is passed down from the parents to their children, we will be taking a look at meiosis.
................To determine the genotype of the parents, a test cross must be performed. According to the interview, Alyssa's mother possesses blood type B, while her father possesses blood type O. The blood types of the four children are as follows: O, O, B, and B. Considering that two of the children are blood type O and the other two are blood type B, the only possible genotypes of the parents are Iᴮi x ii as shown in the Punnett square on the left.
................Since there are four children, the results can easily be compared to a monohybrid square. With the father having the blood type O, which is a recessive blood type, the genotype of the father can be verified as ii. The children have a phenotypic ratio of 50% having the blood type O and 50% having the blood type B. From this it can be concluded that the mother, who has the blood type B, has a recessive allele for blood type O; leading to the genotype Iᴮi.
Meiosis of gametes carrying the alleles for blood type B and blood type O.
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................With the knowledge of what genotypes Alyssa’s parents possess, she decided to share it with her family. When shown the illustrations of how Alyssa and her siblings got their respective blood types, her family was surprised at the fact that the concept of recessive traits also applied to blood type. They initially just thought that Alyssa and her siblings got blood type B and O because both parents were also blood type B and O without proper reasoning behind it.
................On our part, we were also mildly shocked to know that some people actually don't know about this. Something we have thought of to be simple is actually not so common to other people. This made us realize just how significant yet underappreciated genetics may be.
