Lecture_2_bio_intro

The chromosomal locus of a gene might be wrihen 6p213

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Unformatted text preview: e genes differ at one locus are said to have different genotypes. •  A locus (loci for plural) is the specific loca9on of a gene of a DNA sequence on a chromosome. •  A variant of the DNA sequence at a given loca9on is called a allele. •  The ordered list of loci known for a par9cular genome is called a gene4c map. Diploid and polyploid cells whose chromosomes have the same allele of a given gene at some locus are called homozygous, with respect to that gene (otherwise, it is heterzygous). The chromosomal locus of a gene might be wriHen "6p21.3” •  6: chromosome number •  p: posi9on on the chromosome’s short arm (“p”) or long arm (“q”) •  21.3: the posi9on on the arm: region 2, band 1, sub- band 3. The bands are visible under a microscope when the chromosome is stained. 2 8/26/13 •  Genes are shown in rela9ve order and distance from each other based on pedigree studies. •  The chance of the chromosome breaking between A & C is higher than the chance of the chromosome breaking between A & B during meiosis •  Similarly, the chance of the chromosome breaking between E & F is higher than the chance of the chromosome breaking between F & G •  The closer two genes are, the more likely they are to be inherited together (co- occurrence) •  If pedigree studies show a high incidence of co- occurrence, those genes will be located close together on a gene9c map Genotype/Phenotype Phenotype: Blue eyes Brown eyes Genotype:...
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