Alternative forms of a gene?

• A. Alleles
• B. Haploid cell
• C. mRNA
• D. Genetic screening

Answer: (A)

Different versions of a gene are called alleles. An allele is a slightly different version of the same gene that sits at the same location on homologous chromosomes. In diploid organisms you inherit one allele from each parent, so you can be homozygous (two identical alleles) or heterozygous (two different alleles). Alleles arise by mutation and can lead to variation in traits, especially if they alter the protein made or how the gene is regulated. The other terms aren’t about gene forms: a haploid cell has one chromosome set, mRNA is the RNA copy made during transcription, and genetic screening is a test to detect genetic conditions. So alleles best describe the concept of alternative forms of a gene.