A dominant gene does not "subdue" or "cover" a recessive gene. Explain using round and wrinkled peas as your example.
Dominant genes are expressed as phenotypes..the recessive genes are still there. The pea examples is great, and we will be happy to critique your explaination.
To explain the concept of dominant and recessive genes using round and wrinkled peas, we need to understand a few basic principles of genetics.
In Mendelian genetics, genes are responsible for passing on traits from one generation to the next. Each gene exists in different forms, called alleles. An allele can be dominant or recessive, defining how it is expressed in an organism's phenotype or physical appearance.
In the case of round and wrinkled peas, there are two possible alleles for the gene controlling pea texture: the round allele (R) and the wrinkled allele (r). The round allele is dominant, and the wrinkled allele is recessive. Let's explore how this works:
1. A pea plant can have two copies of the same allele or two different alleles (one from each parent). Plants with two copies of the round allele (RR) will exhibit the round phenotype, while plants with two copies of the wrinkled allele (rr) will show the wrinkled phenotype.
2. When a plant possesses one copy of the round allele (R) and one copy of the wrinkled allele (r), it is considered heterozygous (Rr). In this case, the dominant round allele will determine the plant's phenotype, which means it will have round peas.
Now, let's delve deeper into the mechanism behind this:
Genes contain the instructions for making proteins that determine an organism's traits. In the case of pea texture, the gene instructs the production of proteins involved in the formation of starch granules in the peas. The round allele (R) produces a protein that allows starch granules to form normally, resulting in round peas. On the other hand, the wrinkled allele (r) produces a protein that is defective, leading to the abnormal formation of starch granules and hence wrinkled peas.
So, when a pea plant has one copy of the round allele (R) and one copy of the wrinkled allele (r), the protein produced by the round allele (R) masks the effects of the defective protein produced by the wrinkled allele (r). This is why we observe the round phenotype in heterozygous plants (Rr), even though they still possess the wrinkled allele (r).
In summary, a dominant gene, such as the round allele (R) in the case of pea texture, masks the effects of a recessive gene (wrinkled allele, r) when present together in a heterozygous individual (Rr).