Chromosome Mutations and Chromosome Disorders

What is this diagram called? A Karyotype

How many chromosomes are shown on a normal human karyotype? 46

What are the pairs of each type of chromosome called? Homologous chromosomes

Chromosomal mutations - involve many genes and are often fatal Chromosomal mutations - involve many genes and are often fatal. If the zygote develops, the individual is often sterile. Deletions-part of a chromosome is left out Insertion/Duplication - occur when part of one chromatid breaks off and attaches to its sister chromatid.

Inversions-occur when part of a chromosome breaks out and is reinserted backwards Translocations-occur when part of one chromosome breaks off and attaches to a different chromosome

Chromosomal Disorders Nondisjunction-the failure of homologous chromosomes to separate properly during meiosis- both of the homologous chromosomes move to the same pole during meiosis. can result in trisomy, monosomy, or triploidy Homologous chromosomes fail to separate Meiosis I: Nondisjunction Meiosis II

Trisomy - occurs when a gamete with an extra chromosome is fertilized by a normal gamete. results in an individual with an extra copy of one of the chromsomes. In humans this individual would have 47 chromosomes. Monosomy - occurs when a gamete missing a chromosome is fertilized by a normal gamete. results in an individual with a single copy of one of the chromosomes. In humans this individual would have 45 chromosomes.

Triploidy - When a diploid gamete and a normal haploid gamete fuse, the zygote that results is triploid there is no separation of homologous chromosomes causing diploid gametes to be produced. it has three copies of the genetic information. Rare and almost fatal in animals, but much more common in plants often results in larger flowers or fruits of greater commercial value.