What does the notation TT mean to geneticists?
A. Two dominant alleles C. At least one dominant allele B. Two recessive alleles D. 1 dominant allele & 1 recessive allele
The correct answer and explanation is:
The correct answer is A. Two dominant alleles.
Explanation:
In genetics, “TT” represents a genotype where both alleles of a particular gene are dominant. Alleles are different versions of a gene, and each individual inherits two alleles for each gene: one from each parent. These alleles can either be dominant or recessive.
A dominant allele is one that expresses its trait even if only one copy is present. On the other hand, a recessive allele only expresses its trait when both copies are recessive. When both alleles are dominant, like in the case of “TT”, the individual will display the dominant trait.
For example, consider a gene for plant height. If the tall height allele (T) is dominant over the short height allele (t), an individual with the genotype “TT” will be tall, as the dominant allele (T) will express the tall trait. The “tt” genotype would result in a short plant since both alleles are recessive, and the recessive trait is only expressed when both alleles are recessive.
The notation “TT” suggests that the individual has inherited one dominant allele from each parent for this particular gene, and thus will express the dominant phenotype. This is in contrast to other genotypes, such as “Tt” (heterozygous), where there is one dominant allele and one recessive allele, or “tt” (homozygous recessive), where both alleles are recessive.
The concept of dominant and recessive alleles is fundamental in understanding Mendelian inheritance, which explains how traits are passed from one generation to the next.