An allele is a ________.
a. Version of a gene
b. Dysfunctional gene
c. Protein
d. Spare copy of a gene
e. Phenotype

Verified step by step guidance

1. Understand the concept of an allele: An allele is a specific version or variant of a gene. Genes are segments of DNA that code for proteins or traits, and alleles are the different forms of these genes that can exist at a specific locus on a chromosome.
2. Recall that alleles can be dominant or recessive. Dominant alleles mask the expression of recessive alleles in heterozygous individuals. For example, in pea plants, the allele for purple flowers (P) is dominant over the allele for white flowers (p).
3. Eliminate incorrect options: (b) 'dysfunctional gene' is incorrect because not all alleles are dysfunctional; (c) 'protein' is incorrect because alleles are DNA sequences, not proteins; (d) 'spare copy of a gene' is incorrect because alleles are not spare copies but variations of a gene; (e) 'phenotype' is incorrect because phenotype refers to the observable traits, not the genetic variants.
4. Focus on the correct option: (a) 'version of a gene' is the correct answer because it accurately describes what an allele is—a specific form of a gene that can lead to variations in traits.
5. Conclude that the correct answer is (a) 'version of a gene,' as it aligns with the biological definition of an allele.

Key Concepts

Alleles

An allele is a specific version of a gene that occupies a particular position on a chromosome. Alleles can vary in their sequence of DNA, leading to different traits or characteristics in an organism. For example, a gene for flower color may have a purple allele and a white allele, resulting in different flower colors depending on which allele is present.

Genes

Genes are segments of DNA that contain the instructions for building proteins, which perform various functions in the body. Each gene can have multiple alleles, contributing to genetic diversity within a population. Understanding the role of genes is crucial for grasping how traits are inherited and expressed in organisms.

Phenotype

Phenotype refers to the observable physical and physiological traits of an organism, which result from the interaction of its genotype (the genetic makeup) with the environment. For instance, the phenotype of a plant may include its height, flower color, and leaf shape, all of which are influenced by the alleles it possesses and environmental factors.