Gamete formation 2 gamete formation rules an allele

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Gamete Formation 2 Gamete Formation Rules An allele can be present in a gamete only if that individual has that allele For every pair of alleles an individual gamete only gets one Different Pairs of alleles assort independently from one another Example 1 Below is 1 st division of Meiosis 2 nd division of meiosis Example 2 Below is 1 st division of Meiosis
Below is 2 nd division of Meiosis with this you get 4 possible outcome Ab aB AB Ab Linked Genes Gamete Formation Linked genes are genes located on the same chromosome, they are linked because during meiosis the chromosomes are what move (with them their genes) but genes on the same chromosome will move with each other With linked genes the alleles for different genes that are located on the same chromosome will move together during meiosis This will cause a change in the kinds of gametes that can be produced Genes do not assort independently Below is an example of an individual who is heterozygous During the first stage of meiosis 1 daughter cell: A/B 1 daughter cell: a/b Below is an example of an individual who is heterozygous During the second stage of meiosis
2 daughter cell: A/B 2 daughter cell:a/b Product Law The chance that independent events will occur simultaneously is equal to the product of the chances that they will occur separately Multiple the probabilities together Genetic Variation Variations on Mendel’s Theme: These are only variations in phenotype not in how the alleles are inherited Incomplete Dominance Multiple Alleles Co-dominance Sex-Linkage Epistasis/Pleiotropy Polygenic Inheritance Variations in Phenotype Examples of Mendel’s Theme of variations Incomplete Dominance The heterozygous individuals have a phenotype intermediate to the homozygous individuals Ex: Red X White -- Pink Multiple Alleles Individual (diploid): No more than 2 alleles per gene Population: no more than 2n alleles per gene
Co-dominance The heterozygote expresses both alleles (phenotypes) simultaneously AB is an example of co-dominance because you have the A allele and B allele at the same time Sex-Linkage The result of genes located on one of the sex chromosomes (X or Y), but not the other Ex: X-linked: Hemophilia, Red-Green colorblindness, Muscular Dystrophy The diseases above occur more often in men than women because women who have 2 x chromosomes, you have to have 2 copies of the allele (in order to express it) because theses are all recessive conditions. Men only need 1 copy Y-Linked: Hypertrichosis Only found in men because they are the only ones who have why chromosomes Epistasis/Pleiotropy Epistasis: One genes interferes with the expression of another Sickle-cell Disease: 1 gene causes 3 different genotypic effects Pleiotrophy: One genes has multiple phenotypic effects Polygenic Inheritance Multiple genes impacting the same phenotype

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