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Biological Sciences
BIO 105
Bradley Wetherbee

Mendelian Genetics and inheritance Hereditary traits: genes and alleles • The characteristics (traits) that an organism possesses result from the genes (hereditary units) that the organism has • An organism has at most two versions (alleles) for any trait • Can be understood how each of us turned out the way we did based on inheritance of genes from our parents • Can understand trait distribution in population • Can understand existence of negative traits (sickness) in human population • Genes- hereditary info that determines a single trait • Allele- different forms that a gene might take • Tongue rolling or ear lobe attachment determined by genes ◦ Can roll tongue/can't ◦ Attached or not ▪ Two versions for each ◦ One gene that determines tongue rolling-- two alleles ▪ One allele that synthesizes protein that allows tongue rolling ▪ One allele that doesn't • Different forms of traits exist in populations • Traits are controlled by genes • Study of hereditary pioneered by Gregor Mendel ◦ Pea plants ◦ 7 traits ◦ Manipulated fertilization of plants to see how traits are passed to offspring Dominant and recessive alleles • Alleles can either be dominant or recessive ◦ One allele is expressed over another ◦ Dominant allele expressed as uppercase, recessive as lowercase\ • Tongue rolling example: ◦ Dominant: T, Recessive: t ▪ Person may have two dominant alleles (TT), or one dominant and one recessive (Tt) ▪ Person who cannot roll their tongue have two recessive alleles (tt) ◦ Each individual has 2 alleles for tongue rolling ◦ One from each parent ◦ Two versions of a gene ▪ Can roll tongue ▪ Can't roll tongue ◦ When both versions are present (Tt), dominant allele is expressed Homozygous and hete
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