Summary
Alleles of different genes are distributed to gametes independently when the genes lie on separate chromosomes.
In depth
In a dihybrid cross the allele of one gene goes to a gamete independently of the allele of another. This works for genes on different chromosomes or far apart on the same one.
Gametes from AaBb are AB, Ab, aB and ab in equal numbers, giving a 9:3:3:1 phenotype ratio.
Common mistake: the law does not hold for linked genes, which tend to travel together.
Genes on different chromosomes assort independently because the orientation of each homologous pair at metaphase I is random. With n pairs of chromosomes, 2 to the power n combinations are possible: for humans this is 8.4 million before crossing over.
The law fails for linked genes, which Bateson and Punnett first noticed in sweet peas. Mendel's seven traits lie on chromosomes in ways that happened to show independence (some are on the same chromosome but far apart).
Remember: independent assortment concerns different genes, whereas segregation concerns two alleles of the same gene.
Frequently asked questions
What is Law of Independent Assortment?
Alleles of different genes are distributed to gametes independently when the genes lie on separate chromosomes.
Which area of biology covers Law of Independent Assortment, and how advanced is it?
Law of Independent Assortment is one of the 54 topics in Genetics. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Linked Genes, Law of Segregation, Dihybrid Cross.
What should I learn before Law of Independent Assortment?
Law of Independent Assortment is a Beginner topic, so no earlier topic is required. Other Beginner topics in Genetics that pair well with it include Heredity, Gene, Allele.
What topics are related to Law of Independent Assortment?
The closest topics to Law of Independent Assortment are Linked Genes, Law of Segregation, Dihybrid Cross, Crossing Over. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Law of Independent Assortment?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Law of Independent Assortment. To practise the whole of Genetics, use the Genetics quiz.
How is Law of Independent Assortment different from Linked Genes?
Law of Independent Assortment: Alleles of different genes are distributed to gametes independently when the genes lie on separate chromosomes. Linked Genes: Genes close together on the same chromosome tend to be inherited together instead of assorting independently. Read both side by side and note what each one explains.
What is a common mistake about Law of Independent Assortment?
The law does not hold for linked genes, which tend to travel together.
How should I study Law of Independent Assortment step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Linked Genes and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.