Sewall Wright and quantitative genetics

A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait’s inheritance pattern (e.g., dominant or recessive) is known, Punnett squares can also be used to determine the probability of inheriting a phenotype. Punnett squares are applicable in situations where trait inheritance is determined by a single gene locus and traits are independently inherited. However, they cannot predict trait probabilities for more complex genetic inheritance...

A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait’s inheritance pattern (e.g., dominant or recessive) is known, Punnett squares can also be used to determine the probability of inheriting a phenotype. Punnett squares are applicable in situations where trait inheritance is determined by a single gene locus and traits are independently inherited. However, they cannot predict trait probabilities for more complex genetic inheritance...

Trihybrid Crosses
Some of Mendel’s crosses examined three pairs of contrasting characteristics. Such a cross is called a trihybrid cross. A trihybrid cross is a combination of three individual monohybrid crosses. For example, plant height (tall vs. short), seed shape (round vs. wrinkled), and seed color (yellow vs. green).
The F1 generation plants of a trihybrid cross are heterozygous for all three traits and produce eight gametes. Upon self-fertilization, these gametes have an equal chance to...

Gregor Mendel's work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid cell has two variants called alleles inherited from each parent. He suggested that amongst these two alleles, one allele is dominant in character and the other recessive. The combination of alleles determines the phenotype of a gene in an organism.

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 hundreds of loci that influence height, and there are believed to be many more. Due to the high number of genes involved, as well as environmental and nutritional factors, height varies significantly within a given population. The distribution of height forms a bell-shaped curve, with relatively few individuals in the population at the...

Genetic screens are tools used to identify genes and mutations responsible for phenotypes of interest. Genetic screens help identify individuals or a group of people at risk of developing  genetic diseases and help them with early intervention, targeted therapy, and reproductive options.
Forward genetic screens
Forward or “classical” genetic screens involve creating random mutations in an organism’s DNA using radiation, mutagens, or insertion of additional bases, which result in visible changes...