What happens when both alleles for a gene are identical?

When both alleles for a gene are identical, the individual is considered homozygous for that gene. This means that they have two copies of the same allele.

Here are the steps that explain this process:

1. Each individual has two copies of each gene, one from each parent. These copies are called alleles.

2. If the two alleles are identical, they will both code for the same version of the protein that the gene is responsible for.

3. This means that the individual will only be able to produce one version of this protein, regardless of the conditions.

4. This can be beneficial if the allele codes for a beneficial trait, but it can also be harmful if the allele codes for a harmful trait.

5. In some cases, being homozygous for a certain gene can lead to genetic diseases. This is especially true for recessive genetic diseases, which require an individual to have two copies of the harmful allele in order to manifest the disease.

6. On the other hand, being homozygous for a beneficial trait can provide an advantage in certain environments. For example, being homozygous for the allele that provides resistance to malaria can be beneficial in areas where malaria is common.

In conclusion, when both alleles for a gene are identical, the individual is homozygous for that gene and will express the trait that the allele codes for.