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Mendelian genetics and heredity

Mendelian genetics and heredity. Chromosomes, genes and alleles . Definitions. Genotype Phenotype Genes Locus Alleles Dominant / recessive / codominant Homozygous / heterozygous Test cross. Monohybrid crosses.

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Mendelian genetics and heredity

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  1. Mendeliangenetics and heredity

  2. Chromosomes, genes and alleles

  3. Definitions • Genotype • Phenotype • Genes • Locus • Alleles • Dominant/recessive/codominant • Homozygous/heterozygous • Test cross

  4. Monohybridcrosses • A red floweriscrossedwithanother red flower. Some of theoffspring are white. Whatdoesthis mean? • Oneflowercheatedontheother • Thewhitefloweris a mutant • It´snotpossible • Somethingelse

  5. Practicequestions • Tonguerolling (T) isdominant over non-tonguerollling (t). A heterozygousmalecrosses with a homozygousrecessive female. Theyhavefourchildren. What ratio of phenotypes do youexpect in theirchildren? • Show yourworkingusingPunnetgrids.

  6. Practicequestion • 1. Pea plants have two phenotypes, short leaves and long leaves. Long leaves are the dominant trait and short leaves the recessive trait. • Assuming that D is the allele for dominant and d is the allele for recessive write the possible genotypes for a plant with long leaves and a plant with short leaves plant. • Using a Punnet grid establish the offspring of the plants produced by the next combinations, Dd X dd , DD X Dd , • DD X dd , dd X dd. Write the genotypes for each offspring and the phenotype ratio.

  7. Bloodtypes Bloodtypeisanexample of a gene which can de CODOMINANT. Thismeansthattwoalleles can beequallystrong –so whenwecaaryone of eachweget a mixedphenotype: BOTH ALLELES ARE EXPRESSED.

  8. Howisbloodtypeinherited?

  9. Sex chromosomes and gender

  10. Sex chromosomes and gender XX XY X X Y X XX XX XY XY

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