Duplication (Chromosome Mutation) — Definition & Examples

(Video) Mutations

by Amoeba Sisters

This video by the Amoeba Sisters describes four types of chromosome mutations.

Summary

Chromosomes are made up of DNA and proteins. Humans have a total of 46 chromosomes. 23 come from a sperm cell and 23 come from an egg cell.

Duplication happens when a chromosome has extra copies of a gene. So, the chromosome has an area that is repeated.

Other types of mutations include:

• Deletion: some of the genetic material breaks off and is lost
• Inversion: a broken segment flips around and reattaches
• Translocation: a part from one chromosome breaks off and attaches to a different chromosome

If one of these mutations is going to happen, it will occur during meiosis.

Chromosome Duplications

Duplication is when a segment of a chromosome is copied and placed into another chromosome. Duplication happens during meiosis when two misaligned homologous chromosomes have unequal crossing-over. This means that one chromosome will not have a certain segment, while the other chromosome will have two pieces of the segment. All of these chromosomal mutations (deletion, inversion, duplication, translocation) will go unnoticed in the sperm or egg. However, when a mutated egg or sperm becomes fertilized, the mutations that occurred in the parent's cells become noticeable.

What Is Duplication?

Duplication is a type of chromosomal mutation that occurs when a section of a chromosome is repeated. This causes the two homologous chromosomes to have different amounts of genetic material. More specifically, one chromosome will have two copies of a certain area while the other chromosome won't have it at all.

Duplication mutations happen during the crossing-over stage of meiosis.