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Genetics Unraveled: Traits Influencing Evolutionary Patterns

Discover the intricate workings of genetics through pleiotropy, polygenic traits, linked genes, and more. Dive into Mendel's experiments, sex determination, and genetic testing, all shaping Darwin's theory of evolution. Explore the math behind AP Physics in this enlightening journey.

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Genetics Unraveled: Traits Influencing Evolutionary Patterns

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  1. Traits:The Puppeteering of Genetics By: Stephen Romero Aca-Deca 2013

  2. Pleiotropy • A phenomenon in which one gene affects multiple unrelated phenotypic traits • Pleio- = Many; -tropic = affecting • Mendel’s experiment • Mendel observed that pea plants with white flowers also have white stalks, and those that lacked white flowers equally lacked white stalks

  3. Polygenic • A phenomenon in which multiple genes affect a single phenotypic trait • Poly- = many; -genic = of genes • Example include height, weight, and skin color, cancer risk, or any trait in which multiple factors come into play (generally quantitative values) • Colorblindness is an example in humans in which the sex determines this. The X chromosome determines colorblindness, and since men only possess one X, they only need to inherit it from the mother. Women, however, need a color-blindness gene from both the mother and father to exhibit the trait.

  4. Linked Genes: Down w/ the System! • William Bateson, with the help of Edith Saunders and Reginald Punnett, discovered that genes can be linked as a single unit during meiosis within the gametes, leading some traits not to follow the law of independent assortment • Thomas Morgan (Nobel Prize 1933) later proved the theory of gene linkage in relation to the sex chromosome • Meaning that some gene types could mutate with say the Y-chromosome, leaving them to only be present in males

  5. How is Sex Determined? • Sex is generally determined by genetics, but in many species, can also be dependent on: • Environment • Temperature • Chemicals • Social Structure • Also, in terms of sex chromosomes, the Y-chromosome is not always the deciding gene • In flies, the X-chromosome provides the necessary blueprints for both sexes, but requires a second X to activate the female organs. The Y simply replaces the X • In humans however, the Y chromosome determines the sex. The genitals are destined to be ovaries unless the SRY gene (located in the Y chromosome) says otherwise.

  6. Genetic Testing • Pedigree analysis, the process of determining various genes within potential parents, helps genetic counselors allow potential parents to make decisions regarding child-birth based on the risks of disease and abnormalities • Karyotyping is genetic analysis performed on a developing fetuses • Amniocentesis is a the process of extracting fluid from the fetal membrane via long needlein the uterine lining • Chorionic villus sampling (CVS) actually extracts fetal membrane to be biopsied

  7. Darwin’s Theory of Evolution • Individuals within a species vary in their heritable traits; this is referred to as descent with modification • In every generation, more offspring are produced than can be supported by the environment • Individuals with the most favorable variations survive and go on to reproduce and are naturally selected

  8. ~~Math Time~~ (How I feel during AP Physics…)

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