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Traits: The Puppeteering of Genetics

Traits: The Puppeteering of Genetics. By: Stephen Romero Aca-Deca 2013. Pleiotropy. A phenomenon in which one gene affects multiple unrelated phenotypic traits Pleio- = Many; -tropic = affecting Mendel’s experiment

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Traits: The Puppeteering of Genetics

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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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