Genetics what is an allele

On the other hand, a recessive allele is one that is not expressed when its paired allele is dominant. With eye color, the brown eye allele is dominant to the blue eye allele. This means that a child with a blue allele from their mom and a brown allele from their dad will end up with brown eyes.

But a child with two blue alleles will display the blue eye phenotype. A section of DNA that encodes for a certain trait. A variant form of a gene. Genes determine individual traits. Alleles contribute the diversity in phenotype expression. Number per genus locus. Eye color, hair color, skin pigmentation. Blue eyes, brown hair, dark skin. Genes and alleles are essential to basic genetics, but what are the differences between them?

In this guide, we compare genes and alleles and provide simple definitions and examples for both. What is a gene? What is an allele? How are genes and alleles inherited? What is a dominant gene and what is a recessive gene? When an organism is heterozygous at a specific locus and carries one dominant and one recessive allele, the organism will express the dominant phenotype. Alleles can also refer to minor DNA sequence variations between alleles that do not necessarily influence the gene's phenotype.

Further Exploration Concept Links for further exploration gene recessive dominant test cross genotype phenotype haplotype DNA chromosome Hardy-Weinberg equilibrium evolution mutation speciation penetrance SNP allele frequency Hardy-Weinberg equation population bottleneck principle of segregation principle of independent assortment dihybrid cross genetic drift lethal allele principle of uniformity Principles of Inheritance.

Related Concepts You have authorized LearnCasting of your reading list in Scitable. Do you want to LearnCast this session? Being the direct product of gene expression, proteins are the main factors presenting the phenotype by executing their cellular functions.

Proteins can be receptors responsible for presenting antigens to the immune cells, pigments, hormones, antibodies, or enzymes. Some genetic variations involve the change of a single nucleotide, the building block of DNA. Such mutation, referred to as nucleotide substitution, is the most common and simplest form of genetic variation. If a substitution occurs in a coding region within the gene, that will result in amino acid substitution.

For example, the function of an enzyme is to catalyze chemical reactions by binding to their substrates through an active site, a region within the 3D structure of the enzyme that is specifically bound to a substrate in a lock-and-key manner.

Other base substitutions can create a stop codon resulting in the premature termination of translation and the creation of truncated protein products. Mutations can also occur in the form of an addition or deletion of one or a few nucleotides. Try to answer the quiz below to check what you have learned so far about alleles. In this tutorial, find out more about certain types of inheritance that does not follow the Mendelian inheritance patterns.

Examples are incomplete dominance and complete dominance Read More. Gregor Mendel, an Austrian monk, is most famous in this field for his study of the phenotype of pea plants, including the shape of the peas on the pea plants. Know the works of Mendel that set the foundation of genetics. This tutorial presents Gregor Mendel's law of dominance. Learn more about this form of inheritance and how it can be predicted using a Punnett square This tutorial describes the independent assortment of chromosomes and crossing over as important events in meiosis.

Read this tutorial to know more details in each of these meiotic events and how they promote genetic diversity in sexually-reproducing organisms Darwin's Finches are an example of natural selection in action.

They are an excellent example of the way species' gene pools have adapted in order for long term survival via their offspring.

See this tutorial for more elaborate info on natural selection as exemplified by Darwin's finches Genes are expressed through the process of protein synthesis. This elaborate tutorial provides an in-depth review of the different steps of the biological production of protein starting from the gene up to the process of secretion. Also included are topics on DNA replication during interphase of the cell cycle, DNA mutation and repair mechanisms, gene pool, modification, and diseases Skip to content Main Navigation Search.

Dictionary Articles Tutorials Biology Forum. Allele n. Table of Contents. Allele biology definition : variant of a gene controlling the same trait and occupying a specific region on a chromosome called the locus.

Synonyms: allelomorph. Quiz Choose the best answer. Incompletely dominant. A condition wherein two different alleles are expressed somewhat equally Dominance.

Incompletely dominance.