Overview An organism is diploid if it inherits two variants, or alleles, of each gene, one from each parent. These two alleles constitute the genotype ...

Overview A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait’s inheritance pattern ...

Overview In the 1850s and 1860s, Gregor Mendel investigated inheritance by performing monohybrid crosses in pea plants. He crossed two plants that were ...

Overview To determine whether traits are inherited together or separately, Gregor Mendel crossed pea plants that differed in two traits. These parental ...

Overview A pedigree is a diagram displaying a family’s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or ...

Overview The probability of inheriting a trait can be calculated using the sum and product rules. The sum rule is used to calculate the probability of ...

The Concept of Multiple Allelism Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, ...

When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have uncovered ...

In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence ...

Pleiotropy is the phenomenon in which a single gene impacts multiple, seemingly unrelated phenotypic traits. For example, defects in the SOX10 gene cause ...

Many human characteristics, like height, are shaped by both nature—in other words, by our genes—and by nurture, or our environment. For ...

When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the F1 ...

While Mendel’s Law of Segregation states that the two alleles for one gene are separated into different gametes, a different question of how ...

In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be ...

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological ...

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, ...

Most DNA resides in the nucleus of a cell. However, some organelles in the cell cytoplasm⁠—such as chloroplasts and mitochondria⁠—also ...

In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of ...

Alleles are different forms of the same gene. Humans and other diploid organisms inherit two alleles of every gene, one from each parent. An allele is ...