The Relationship of Genes to Chromosomes

The Relationship of Genes to Chromosomes - The Relationship...

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The Relationship of Genes to Chromosomes The alternation of two genes in individuals and one gene in gametes is of course reminiscent of the behaviour of chromosomes, diploid in most tissues but haploid in sperm and egg. We now know the reason why this is so, genes are carried on chromosomes, encoded in the DNA. Human pedigrees Before we consider human Mendelian inheritance it is convenient to consider the symbols used to draw pedigrees. Generations are numberered from the top of the pedigree in uppercase Roman numerals, I, II, III etc. Individuals in each generation are numbered from the left in arab numberals as subscripts, III 1 , III 2 , III 3 etc. Modes of inheritance Most human genes are inherited in a Mendelian manner. We are usually unaware of their existence unless a variant form is present in the population which causes an abnormal (or at least different) phenotype. We can follow the inheritance of the abnormal phenotype and deduce whether the variant allele is dominant or recessive. autosomal dominant
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The Relationship of Genes to Chromosomes - The Relationship...

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