Question

Define allele, homozygous, heterozygous, genotype, and phenotype. (p. 482)

Short answer

Question: Provide a brief definition of each of the following genetics-related terms: allele, homozygous, heterozygous, genotype, and phenotype. Answer: An allele is an alternative version of a gene responsible for variations in a trait. Homozygous refers to an organism with two identical alleles of a gene, while heterozygous describes an organism with two different alleles. Genotype is the genetic makeup of an organism concerning specific genes, and phenotype is the observable expression of an organism's genotype.

Step-by-step solution

1. Define Allele

Allele refers to different forms of a specific gene that can be found at a particular locus on a chromosome. In other words, alleles are alternative versions of a gene, responsible for variations in a certain trait within a species.

2. Define Homozygous

An organism is said to be homozygous for a specific gene when it carries two identical alleles of that gene, one from each parent. Homozygous organisms can be either homozygous dominant (having two dominant alleles) or homozygous recessive (having two recessive alleles).

3. Define Heterozygous

An organism is heterozygous for a specific gene when it carries two different alleles of that gene, one from each parent. In heterozygous organisms, the dominant allele usually determines the phenotype, while the recessive allele is masked.

4. Define Genotype

The genotype refers to the genetic makeup of an organism with respect to specific genes or a particular set of genes. In other words, it refers to the combination of alleles an individual possesses - for example, homozygous dominant (AA), homozygous recessive (aa), or heterozygous (Aa).

5. Define Phenotype

The phenotype of an organism is the observable expression of its genotype, which includes its physical, biochemical, and physiological traits. It is the outcome of the interaction between the organism's genetic makeup (genotype) and its environment, determining characteristics such as hair color, eye color, height, and disease susceptibility.