Can a person have more than two alleles for a single gene?

If two alleles are possible for a single gene,?

• a. the sequences of the DNA for each allele would be different and produce different proteins. b. the sequences of the DNA would be identical for each allele and would produce identical proteins. c. the sequences of the DNA would be identical for each allele, but they would produce different proteins. d. the sequences of the DNA would be different for each allele, but they would produce identical proteins. e. This cannot be, because alleles are based on different genes.

• Answer:

  All of the answers are wrong. However, since you have to pick one, a is the closest to being correct. The first part of the answer is correct, that two alleles of a single gene will have different DNA sequences. However, these two alleles will not necessarily produce different products. Also, the final gene products are not necessarily proteins (they could be RNA). If a protein is produced, those proteins may be different, but don't have to be. The DNA sequence could be different and thus you have different alleles, but the sequences may be silent mutations that do not result in a changed protein so the proteins produced may be identical, even though the DNA sequences between the two alleles are different. Also, the differences between the alleles could be in non-coding regions and also wouldn't show up in the protein products. An allele is defined as an alternate form of a gene; this doesn't specifically refer to a protein product.