Chromosomal mutations:
These mutations involve most or all of a chromosome, which is why they affect a number of genes. Types of chromosomal mutations include:
- Deletions: the loss of a part of a chromosome.
- Duplications: where a section of chromosomes occur twice. This may happen if part of a chromatid breaks off and joins onto a wrong one.
- Inversions: where breaks occur in a chromosome and the broken piece joins back in, but the wrong way around. This changes the order of genes on the chromosome and it may disrupt the pairing of others.
- translocations: where part of a chromosome breaks off and is re-joined to the wrong chromosome.
- non-disjunctions: where, during meiosis, a chromosome pair does not separate, so that one daughter cell has an extra chromosome and one daughter cell has one less than the normal number. These are sometimes not referred to as mutations but as aneuploidy- a change in the chromosome number.
- Deletions: the loss of a part of a chromosome.
- Duplications: where a section of chromosomes occur twice. This may happen if part of a chromatid breaks off and joins onto a wrong one.
- Inversions: where breaks occur in a chromosome and the broken piece joins back in, but the wrong way around. This changes the order of genes on the chromosome and it may disrupt the pairing of others.
- translocations: where part of a chromosome breaks off and is re-joined to the wrong chromosome.
- non-disjunctions: where, during meiosis, a chromosome pair does not separate, so that one daughter cell has an extra chromosome and one daughter cell has one less than the normal number. These are sometimes not referred to as mutations but as aneuploidy- a change in the chromosome number.