Independent Assortment, Incomplete Dominance, Co-dominance, Multiple Alleles, and Polygenic Traits

1. Independent Assortment, Incomplete Dominance, Co-dominance, Multiple Alleles, and Polygenic Traits Lab Biology

2. Monohybrid cross

3. Genes • Independent Assortmentis simply stating that the genes for one trait separate independently, without influencing the genes of another trait

4. Dihybrid crosses • Two traits are followed • Green dominant over yellow • GG gg • Round dominant over wrinkled • RR rr • GGRR x ggrr

5. Dihybrid crosses-

8. Complete Dominance • Genes that show simple patterns of dominant and recessive alleles have complete dominance • Some forms of a gene are dominant and others are recessive

9. Incomplete Dominance • Genes with alleles that are neither dominant nor recessive give rise to a blended phenotype, for example a flower that possesses the heterozygous gene for flower color, Rr, (R being red color and r being white color) may have pink flowers because neither is dominant

11. Chocolate lab BYBlack lab BBYellow lab YY

12. Co-Dominance • This situation occurs when both alleles contribute to phenotype • For example, in certain varieties of chicken, the allele for black feathers is co-dominant with the allele for white feathers. Heterozygous chickens have a color describe as a speckled black and white

16. Black BBWhite WWSpotted BW

17. Co dominace or incomplete dominance • Have to be told what kind of domiance it is • Use two different letters for a trait • Both capitols • Some times use superscript • CBC B black chicken • C B C W speckled chicken

18. Multiple alleles • More than two alleles for a trait • hair

19. Multiple Alleles blood types • Many genes have more than two alleles and are therefore said to have multiple alleles • This does not mean that an individual can have more than 2 alleles, it only means that more than two possible alleles exist in a population • An example of multiple alleles includes human blood types, ABO

20. Linked traits • Traits found on same chromosome are linked. • Closer together they are on same chromosome the more likely they are to be linked

21. Crossing over • When homologous chromosomes pair up in meiosis they can tangle and exchange material • This can cause a mutation or change in the chromosome

23. Polygenic Traits • Many traits are produced by interactions of several genes, these are called polygenic traits • An example of a trait controlled by many genes is human skin color

24. Polygenetic traits with pennies • Male 5ft 7 3 tails 3 heads • Female 5 ft 5 4 tails 2 heads • Can child be 5 ft 11? • male can give 3 heads • female can give 2 heads • child would be 5 heads and 1 tail • 5 ft 11 • Yes!