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

A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait’s inheritance pattern (e.g.,…

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

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

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

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

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…

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

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…

Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, normally possess only two…

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

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

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…

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…

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

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

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

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

Systematic identification and characterization of genetic perturbations have proven useful to decipher gene function and cellular pathways. However,…

Forward genetic screening in model organisms is the workhorse to discover functionally important genes and pathways in many biological processes. In…

Comprehensive genomic analysis has uncovered surprisingly large numbers of genetic alterations in various types of cancers. To robustly and…