Need help from an expert?
The world’s top online tutoring provider trusted by students, parents, and schools globally.
Mendel's law of segregation states that allele pairs separate during gamete formation, and randomly unite at fertilisation.
Mendel's law of segregation, also known as the first law of inheritance, is a fundamental principle in genetics, discovered by Gregor Mendel, a 19th-century Austrian monk and scientist. Mendel conducted his experiments on pea plants, studying seven distinct traits, including seed shape, flower colour, and stem length. His observations led him to formulate this law, which explains how traits are passed from parents to offspring.
According to the law of segregation, each individual organism possesses two alleles for any particular trait, and these alleles segregate (separate) during the formation of gametes (eggs and sperm). Each gamete then contains only one allele for each trait. When fertilisation occurs, the offspring receives one allele from each parent, reestablishing the pair of alleles in the offspring. This explains why offspring inherit traits from both parents but are not an exact replica of either.
For example, consider a pea plant trait – seed colour, which can be either yellow or green. The yellow colour is determined by the dominant allele (Y), and the green colour by the recessive allele (y). A plant with a YY or Yy combination will have yellow seeds, while only a yy plant will have green seeds. If a Yy plant self-fertilises, the alleles separate during gamete formation, resulting in half the gametes carrying Y and the other half carrying y. When these gametes unite at fertilisation, they form YY, Yy, and yy offspring in a predictable ratio.
This law of segregation is a cornerstone of genetics, explaining not only how traits can be passed from generation to generation, but also why variations exist within species. It's important to note, however, that this law applies to genes that are located on separate chromosomes or far apart on the same chromosome. Genes that are close together on the same chromosome tend to be inherited together, a phenomenon known as genetic linkage.
Study and Practice for Free
Trusted by 100,000+ Students Worldwide
Achieve Top Grades in your Exams with our Free Resources.
Practice Questions, Study Notes, and Past Exam Papers for all Subjects!
The world’s top online tutoring provider trusted by students, parents, and schools globally.