Mess up my notes part 2 00:01:40And the white snapdragon will have the genotype small r and small r. Now, when the alleles combine, the result is always big R and small r. So, in incomplete dominance red and white are neither dominant nor recessive. So instead, both alleles are present in the offspring, resulting in pink snapdragons. 00:02:19 So I'm going to write big R and small r. Again, you see a blending of the colors. Red plus white makes pink.
Section 4
00:00:00TEACHER: Now, let's look at another way trait involving one gene with two alleles that are inherited. Codominance is an inheritance pattern in which the alleles are neither recessive nor dominant, and both alleles are expressed in the offspring. So, an example of this inheritance pattern can be observed when a black rooster here, on the left oh,
00:00:26there goes my neighbor's rooster, is crossed with a white hen, which is in the middle. And the offspring is a chicken that has black and white feathers. That can be very annoying in the morning time. This type is what is called a speckled chicken. The speckled chicken has both white feathers from her mom and black feathers from her dad.
00:00:53Both feather colors are dominant and codominant. Now let's use a Punnett Square to show codominance. Suppose a plant with purple flowers, as you can see here, is crossed with a plant that has white flowers. The allele that produces purple flowers is capital F superscript p, so we're just going to call it Fp. And the allele that produces white flowers is capital F and superscript w, so we'll just call it Fw.
00:01:30Now notice that for both alleles, the capital F represents the allele, and the super scripts represent the colors. If we combine the alleles of the parents right here, well, what do we get? We get these genotypes, Fp and Fw. Notice that all offspring have the same genotype Fp and Fw.
00:02:05Because purple and white are neither dominant nor recessive, the offspring shows both colors, purple and white, are observed. So therefore, you get Fp and Fw. In other words, both alleles are dominant or codominant.