Mendelian Genetics

Genetics Graphic Organizer Term Symbol Example From Mrs. Fowlkes Example from class Example from you! Allele Homozygous Heterozygous Dominant Recessive Phenotype Genotype Codominance Incomplete dominance

Terms continued… Allele: the different versions of a trait Example: purple flowers vs. white flowers Dominant: one a single allele is present it is expressed it is dominant Recessive: only expressed when both alleles are the recessive trait.

Incomplete Dominance Some characteristics do not exhibit a dominant trait and therefore the phenotype is an intermediate. For example in snapdragon (flowers) red nor white is dominant over the other so the outcome of their offspring results in PINK flowers!

CFU… Using the characteristics from the celebrity babies which ones are a result of incomplete dominance?

Codominance Ia Ib I Ia Ib Ic Similar to incomplete dominance codominance is the result of both alleles being strong enough to be expressed. For example: Blood Type- Possible alleles are A, B, O, Ia Ia A Ia Ib AB Ia I Ib Ib B Ib I II O Ia Ib Ic

Law of Segregation The law of segregation states that a pair of factors is separated, during the formation of gametes. This makes sure that only one set of genes comes from each of the parents.

CFU What is codominance? The law of segregation states that…

Law of Independent Assortment The law of independent assortment states that factors for individual characteristics are distributed independent of one another. The law of independent assortment is observed only for genes that are located on separate chromosomes or are far apart on the same chromosome.

CFU What genetic principle states that during meiosis, alleles for one characteristic are randomly separated independent of alleles for the other characteristic?

Dihybrid Cross A cross in which two characteristics are crossed. Dihybrid crosses represent independent assortment by demonstrating the outcome of possible offspring from two different genes in a single cross. For example flower color A = purple (dominant) a = white (recessive) and stem length: B = tall b = dwarf

Dihybrid Cross Ratios 1 AABB 2 AABb 2 AaBB 4 AaBb 1 AAbb 2 Aabb 1 aaBB Tall; Purple Flowers (9) Tall; White Flowers (3) Dwarf; Purple Flowers (3) Dwarf; White Flowers (1)