Prepa Tec_Biology II.- Essay on Mixed Twins.docx

Prepa Tec_Biology II.- Essay on Mixed Twins.docx - Biology...

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Biology II “Essay on Mixed Twins” Diego Espinosa Lima and Juan Pedro Quiroz Zendejas A01652674 A01652571 302 January 31st, 2018 “Essay on Mixed Twins” Variation and heredity in eukaryotic organisms occur during sexual reproduction, where offsprings receive genes, which are passed through gametes. Gametes are produced during meiosis, which only occurs with diploids cells, as the daughter cells of this process will be haploid, meaning that they will receive half the genetic material from the parents. Meiosis allows genetic variation through independent assortment of chromosomes and crossing-over. Through independent assortment of chromosomes, homologous pairs of chromosomes orient randomly during Metaphase I, allowing maternal and paternal sort independently into other pairs. This independent assortment has 2 23 possibilities in humans, as there are two possible positions for 23 chromosomes. When gametes join through fertilization, a zygote is produced, which has about 7 trillion diploid combinations. Gregor Mendel, whose theories on heredity allowed a bigger understanding of the traits of a population, studied the possible traits that an offspring could express. Mendel proposed the “Particulate Hypothesis”, which refers to the idea that parents pass on discrete heritable units that are known as genes nowadays. This theory allowed the proposal of laws, like the law of segregation and the law of independent assortment. The law of segregation states that genes have alternative forms, called alleles (Mastering Biology, 2016). Through this law, it is explained that each organism inherits one allele for each gene from each parent. In heterozygotes, as the alleles are different, the one that will be expressed is dominant, which masks the recessive allele. On the other hand, homozygotes have identical alleles of a given gene and are known as true-breeding (Mastering Biology, 2016). The law of independent assortment states that the allele a gamete receives for one gene does not influence the allele received for another gene (Khan Academy, 2018). Although
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