The expansion of a binomial distribution produces a normal curve which displays a maximum frequency for the middle values of the data spread and tapers off symmetricaly toward the increasingly rare events at either extreme. A rudimentary set-up for a normal distribution appears in the section dealing with quantitative genes. In that section, four independently assorting alleles with identical phenotypic effects but belonging to two separate genes produced a phenotypic spread of
1:4:6:4:1. To review that material, click on the appropriate button below. Note that you can return to this card from that section of the stack. Often, data spreads in genetics assume a normal distribution because of the binomial nature of the genetic mechanism. With many genes assorting across the genotype, the distribution assumes a smooth curve as can be seen in the diagrams on the right. Flip to the next card.