Unit 4 Reflection

Recently, we performed the Coin Sex Lab, which demonstrated relationship between genetics and inheritance. We used the flipping of coins to model the process of meiosis and the randomness of the splitting of chromosomes and recombination of genes, in order to try to get an accurate representation of inheritance. One of the scenarios we tested was a dihybrid cross, where we crossed two dihybrid heterozygous genes, and the expected results was a phenotypic ratio of 9:3:3:1, our results almost matching with a ratio of  8:4:2:2. I think our results supported the expected results, excluding the minor discrepancies of 1 additional or less result. This is because when crossing two dihybrid heterozygous genes the dominant alleles are apparent and therefore this is also more likely to be apparent in their offspring. For example, if the dominant alleles are brown hair and brown eyes, then the offspring are more likely to get brown hair blue eyes, and it is very rare to get the recessive alleles to be apparent in traditional dominance. Although probability can get give us an educated guess of what results will be, it cannot predict an offspring's traits exactly because in the end genes will combine randomly and unpredictably, overruling any use of probability. Knowing how genetics and inheritance relate to our lives is important, and can help us understand more about ourselves and our entire family, including our ancestors and even our potential children in the future.

In Unit 4, we learned all about genetics and inheritance. In the beginning, we learned about the cell cycle and the process of mitosis During mitosis, there are several steps, including interphase, prophase, metaphase, anaphase, telophase, and cytokinesis, where the cell grows, duplicates DNA and splits into two physically and genetically identical cells. Then we began building on the subject of genetics and reproduction, and asked the question: Why is Sex so great? We learned that there were two main methods of reproduction, asexual and sexual reproduction, both with there costs and benefits. On one hand there was asexual reproduction, where there is one "parent" that splits, or creates, two genetically identical organisms. Although asexual reproduction is quick and easy, it is very difficult for species that use this method to survive because a simple virus or parasite could come along and wipe out the entire population. On the other hand there is sexual reproduction, where there are two parents that each contribute half of the offspring's DNA through sex cells, producing genetically variant offspring. Sexual reproduction has some costs to because it takes a lot of time and energy, exposes the parents to parasites and STDs, creates genetic combinations that are bad, and creates competition over mates. Diving deeper into the subject of sex, we found that sex was determined by a pair of sex chromosomes (XX is female, XY is male), carried in sex cells called gametes, and other traits were determined 22 other non-sex chromosomes, called autosomes. Gametes are created in a process called meiosis, which similar to mitosis splits, but splits twice in order to form 4 daughter cells, containing sister chromatids. Next we learned about Gregor Mendel's discoveries and his revelation about how great sex is. He discovered that traits were determined by two copies of a gene, and he also found that genes come in different versions, called alleles some more dominant over others, which are either homozygous or heterozygous. In addition, he found that you could predict the phenotype, the physical trait, using the genotype, the alleles, of an organism. He also had two important conclusions, first, the law of segregation, which states that gene pairs split during meiosis, and second, the law of independent assortment, which states that gene pairs split randomly during meiosis. Finally, in inheritance, there are several complications, includiong incomplete dominance, which is the blending of alleles, codominance, where both alleles are apparent, gene linkage, epistasis, multifactorial disorders, and polygenetics.

During Unit 4, I learned how genetics and inheritance were an important part in biology and in my life. Using genetics, I could predict the traits that my children and grandchildren would have, and even trace my own traits back to my ancestors. Inheritance can tell us what the costs of having a child could be, including STDs and passing diseases onto offspring, but in addition it could also tell us the benefits of having a child and the amazing traits that could potentially be passed onto the next generation. In addition, in this unit we created infographics that we used to show the important concepts in genetics, and also gave me a new way to express information creatively and clearly. Overall, during this unit I learned a lot about genetics and inheritance, my own traits and gene pool, and more about what biology offers.