遺傳學概念及理論英文版(編輯修改稿)
2025-02-14 20:41 本頁面
【文章內容簡介】 bbit that is homozygous dominant for black coat and heterozygous for straight hair. Then give the phenotypic ratio for the first generation of offspring. BBHH X BBHh Possible gametes: BH BH Bh (Hint: Only design Punt squares to suit the number of possible gametes.) Phenotypes: Sex Determination ? People – 46 chromosomes or 23 pairs ? 22 pairs are homologous (look alike) – called autosomes – determine body traits 1 pair is the sex chromosomes – determines sex (male or female) ? Females – sex chromosomes are homologous (look alike) – label XX Males – sex chromosomes are different – label XY XX XX XY XY X Y ? What is the probability of a couple having a boy? Or a girl? Chance of having female baby? 50% male baby? 50% Who determines the sex of the child? father X X Inplete dominance and Codominance ? When one allele is NOT pletely dominant over another (they blend) – inplete dominance Example: In carnations the color red (R) is inpletely dominant over white (W). The hybrid color is pink. Give the genotypic and phenotypic ratio from a cross between 2 pink flowers. RW X RW RR RW RW WW R W R W Genotypic = 1 RR : 2 RW : 1 WW Phenotypic = 1 red : 2 pink : 1 white ? When both alleles are expressed – Codominance Example: In certain chickens black feathers are codominant with white feathers. Heterozygous chickens have black and white speckled feathers. Sex – linked Traits ? Genes for these traits are located only on the X chromosome (NOT on the Y chromosome) ? X linked alleles always show up in males whether dominant or recessive because males have only one X chromosome ? Examples of recessive sexlinked disorders: 1. colorblindness – inability to distinguish between certain colors Color blindness is the inability to distinguish the differences between certain colors. The most mon type is redgreen color blindness, where red
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