Lesson 3: Non-Mendelian Genetics: Incomplete and CoDominance

Question 1

Inheritance beyond Mendel’s Laws

Answer 1

Mendel found that inherited traits were either dominant or recessive. However, some organisms show different patterns of inheritance
—these do not follow simple Mendelian genetics

Question 2

Incomplete Dominance

Answer 2

-not all traits are purely dominant or purely recessive, sometimes neither of the allele could trolling a trait are dominant
-this leads to a blending of the two traits called incomplete dominance
-examples of incomplete dominance can be seen in many plant species

Question 3

snapdragon example - incomplete dominance

Answer 3

-the homozygous dominant genotypes for flower colour expresses as red
-the homozygous recessive genotypes for flower colour expresses as white
— the heterozygous genotypes for flower colour expresses as
pink
-the incomplete dominance of the alleles for the flower colour lead to a blending of the traits in the heterozygous genotype
-inheritance of traits that show incomplete dominance follows Mendel’s law of segregation and independent assortment
-however, as neither of the alleles are dominant the offspring won’t display the expected Mendelian ratios

Question 4

Co-dominance

Answer 4

-in the cases when both alleles for a trait may be dominant
—alleles are said to be co-dominant because both alleles are expressed in the heterozygous individual

Question 5

example of co-dominance- coat colour in cows

Answer 5

-in cow coat colour is controlled by several dominant alleles. This is written by using the same uppercase letter to denote the trait and a subscript is added to note which allele is present.
C^WC^W = white cow
C^RC^R = red cow
C^WC^R = roan cow
…