ZOL 141 1st Edition Lecture 14 Outline of Last Lecture I Pedigrees II Patterns of Inheritance a Autosomal dominant traits i Ex achondroplaysia ii Ex Marfan Syndrome Outline of Current Lecture II Five patterns of inheritance III Autosomal Recessive a Patterns that suggest this b Example cystic fibrosis IV Sex linked traits Current Lecture Patterns of Inheritance Autosomal dominant Autosomal recessive Xlinked dominant Xlinked recessive Y linked Autosomal recessive Patterns that suggest autosomal recessive inheritance of rare traits o Trait expressed in males and females roughly equal proportions o Trait appears in offspring of unaffected parents o Offspring of affected parents must be affected Assigning Genotypes o When considering autosomal traits an uppercase letter represents a dominant allele and lowercase represents recessive allele Example Cystic fibrosis o Symptoms Very salty skin Body produces mucus that is abnormally thick and sticky Abnormal mucus can clog airways o o Abnormal mucus blocks ducts of pancreas preventing digestive enzymes from reaching intestines to aid digestion Reproductive system affected Causes Mutations in CFTR gene lead to production of cystic fibrosis transmembrane conductance regulator protein that is dysfunctional CFTR protein is channel transports chloride ions into and out of cells Flow of chloride ionds help control movement of water in tissues which is necessary for production of thin freely flowing mucus Treatments No known cure Treatment of symptoms e g airway clearance pancreatic enzyme supplements Sex linked traits X chromosome is medium sized and has many genes Y chromosomes is small and has few genes Males are hemizygous for genes on the x chromosome Distinct patterns of inheritance
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