Summary
Genes close together on the same chromosome tend to be inherited together instead of assorting independently.
In depth
Genes on the same chromosome tend to move together, producing more parental combinations than recombinants. The closer the genes, the less chance of crossing over between them. Morgan's fruit fly experiments showed this in 1910.
Recombination frequency measures distance, allowing maps.
Bateson and Punnett found in sweet peas that purple and long were inherited together more often than expected. Morgan explained this by linkage and recombination in Drosophila. Linkage is shown by a test cross with many parental types and few recombinants, and recombinant frequency never exceeds 50 percent, which is equal to independent assortment.
Cis (coupling) and trans (repulsion) arrangements matter: in a heterozygote, two dominant alleles on the same chromosome give a different pattern from one on each. Linkage allows disease genes to be located through nearby markers.
Remember: linked genes are on the same chromosome and tend to be inherited together unless a crossover separates them.
Frequently asked questions
What is Linked Genes?
Genes close together on the same chromosome tend to be inherited together instead of assorting independently.
Which area of biology covers Linked Genes, and how advanced is it?
Linked Genes is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Law of Independent Assortment, Test Cross, Crossing Over.
Can you give an example of Linked Genes?
Eye colour and wing shape genes in Drosophila deviate from 9:3:3:1.
What should I learn before Linked Genes?
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Linked Genes. Intermediate topics assume the Beginner vocabulary.
What topics are related to Linked Genes?
The closest topics to Linked Genes are Law of Independent Assortment, Test Cross, Crossing Over, Dihybrid Cross. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Linked Genes?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Linked Genes. To practise the whole of Genetics, use the Genetics quiz.
How is Linked Genes different from Law of Independent Assortment?
Linked Genes: Genes close together on the same chromosome tend to be inherited together instead of assorting independently. Law of Independent Assortment: Alleles of different genes are distributed to gametes independently when the genes lie on separate chromosomes. Read both side by side and note what each one explains.
How should I study Linked Genes 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 Law of Independent Assortment and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.