遺傳學(xué)概念及理論英文版(已修改)
2025-01-30 20:41 本頁面
【正文】 Geics Notes Who is Gregor Mendel? Principle of Independent Assortment – Inheritance of one trait has no effect on the inheritance of another trait “Father of Geics” Traits ? Geics – study of how traits are passed from parent to offspring ? Traits are determined by the genes on the chromosomes. A gene is a segment of DNA that determines a trait. ? Chromosomes e in homologous pairs, thus genes e in pairs. Homologous pairs – matching genes – one from female parent and one from male parent ? Example: Humans have 46 chromosomes or 23 pairs. One set from dad – 23 in sperm One set from mom – 23 in egg Gene for eye color (blue eyes) Gene for eye color (brown eyes) Homologous pair of chromosomes ? One pair of Homologous Chromosomes: Alleles – different genes (possibilities) for the same trait – ex: blue eyes or brown eyes Dominant and Recessive Genes ? Gene that prevents the other gene from “showing” – dominant ? Gene that does NOT “show” even though it is present – recessive ? Symbol – Dominant gene – upper case letter – T Recessive gene – lower case letter – t Dominant color Recessive color Example: Straight thumb is dominant to hitchhiker thumb T = straight thumb t = hitchhikers thumb (Always use the same letter for the same alleles— No S = straight, h = hitchhiker’s) Straight thumb = TT Straight thumb = Tt Hitchhikers thumb = tt * Must have 2 recessive alleles for a recessive trait to “show” ? Both genes of a pair are the same – homozygous or purebred TT – homozygous dominant tt – homozygous recessive ? One dominant and one recessive gene – heterozygous or hybrid Tt – heterozygous BB – Black Bb – Black w/ white gene bb – White Genotype and Phenotype ? Combination of genes an anism has (actual gene makeup) – genotype Ex: TT, Tt, tt ? Physical appearance resulting from gene makeup – phenotype Ex: hitchhiker’s thumb or straight thumb White fur (b) Punt Square and Probability ? Used to predict the possible gene makeup of offsp
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