Achondroplasia is a dominant trait that causes a characteristic form of dwarfism. In a survey of 50,000 births, five infants with achondroplasia were identified. Three of the affected infants had affected parents, while two had normal parents. Calculate the mutation rate for achondroplasia and express the rate as the number of mutant genes per given number of gametes.

Key Concepts

Dominant and Recessive Traits

In genetics, traits can be classified as dominant or recessive based on their inheritance patterns. A dominant trait, like achondroplasia, only requires one copy of the mutant allele to be expressed in the phenotype. This means that if an individual inherits the dominant allele from one parent, they will exhibit the trait, regardless of the other allele inherited.

Mutation Rate

The mutation rate refers to the frequency at which new mutations occur in a given gene or organism over a specific time period. It is often expressed as the number of new mutations per generation or per gamete. In the context of achondroplasia, calculating the mutation rate involves determining how many new cases arise in relation to the total number of gametes produced.

Gametes and Genetic Transmission

Gametes are the reproductive cells (sperm and eggs) that carry genetic information from one generation to the next. Each gamete contains half the genetic material of an individual, and during fertilization, they combine to form a zygote. Understanding the role of gametes is crucial for calculating mutation rates, as it helps in determining how many opportunities exist for mutations to be passed on to offspring.