Summary
Large structural changes including deletions, duplications, inversions and translocations of chromosome segments.
In depth
Deletion removes a segment (cri-du-chat is a deletion of chromosome 5p), duplication repeats a segment, inversion flips it and translocation moves a piece to another chromosome (Philadelphia chromosome 9;22 in leukaemia). Large changes can disrupt gene dosage and meiosis.
Balanced rearrangements may have no effect on the carrier but cause unbalanced gametes.
Structural changes have consequences from gene dosage and position effects. Translocation between chromosomes 9 and 22 creates the Philadelphia chromosome and the BCR-ABL fusion gene found in chronic myeloid leukaemia. Familial Down syndrome can come from a Robertsonian translocation where chromosome 21 is joined to 14.
Inversions can suppress crossing over and keep gene combinations together (as in supergenes), while duplications provide raw material for new genes, as with the globin family. Balanced rearrangements may cause no symptoms but result in unbalanced gametes and miscarriage.
Example: cri-du-chat syndrome, from a deletion of part of chromosome 5, is named for the cat-like cry of affected infants.
Frequently asked questions
What is Chromosomal Mutations?
Large structural changes including deletions, duplications, inversions and translocations of chromosome segments.
Which area of biology covers Chromosomal Mutations, and how advanced is it?
Chromosomal Mutations 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 Crossing Over, Karyotype, Allele.
Can you give an example of Chromosomal Mutations?
A Robertsonian translocation can cause familial Down syndrome.
What should I learn before Chromosomal Mutations?
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Chromosomal Mutations. Intermediate topics assume the Beginner vocabulary.
What topics are related to Chromosomal Mutations?
The closest topics to Chromosomal Mutations are Crossing Over, Karyotype, Allele, Transposable Elements. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Chromosomal Mutations?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Chromosomal Mutations. To practise the whole of Genetics, use the Genetics quiz.
How is Chromosomal Mutations different from Crossing Over?
Chromosomal Mutations: Large structural changes including deletions, duplications, inversions and translocations of chromosome segments. Crossing Over: Exchange of segments between homologous chromosomes in prophase I that creates new allele combinations. Read both side by side and note what each one explains.
How should I study Chromosomal Mutations 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 Crossing Over and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.