00:01
Allelophore green pod, capital g, is dominant to allelophore yellow pod, lower g.
00:05
You isolate a pea plant with green pea pod and want to determine if the genotype of this isolated pea plant is homozygous, capital g, or heterozygous, capital g, lower g.
00:20
You decide to perform a test cross.
00:22
So in genetics, a test cross involves breeding the individual with a phenotypically recessive individual.
00:30
Explain how a test plot would allow you to determine the genotype of your isolated pea plant and be specific regarding all possible outcomes of your test cross.
00:41
So in our case, you have a capital g allele, which stands for green, and a lower g is recessive yellow.
00:54
Now, due to the combination of different alleles, you're going to have three different genotypes, heterozygous, homozygous, capital g, heterozygous, capital g, lower g, and homozygous, lower g.
01:08
Now, homozygous, capital g is going to be green because it carries two dominant alleles.
01:18
For heterozygous, due to having a dominant allele, this also is going to show green phenotype.
01:25
The last one, homozygous, lower g, having two recessive alleles, so it will show recessive phenotype, yellow.
01:34
So this is genotype and this is phenotype.
01:50
Now, in our example, you are isolating a pea plant that is green, so you have no idea if this is a green for homozygous or green for heterozygous.
02:05
Now, you're going to perform a test cross.
02:07
So let's say, in our first case, if the green plant is homozygous, capital g.
02:17
Now, the test cross is to cross the individual that you want to find out with a phenotypically recessive individual.
02:28
So this is going to be the yellow.
02:31
Phenotypically recessive, we know that the genotype must be homozygous, lower g.
02:36
So this is test cross.
02:41
Now, let's do the punnett square.
02:44
So if the green pea plant is homozygous, capital g, it will produce two possible alleles.
02:52
They're the same allele, capital g and capital g.
02:56
So the alleles separate during gametes formation.
03:00
And the test cross parent, homozygous, lower g, also separate...