Chromosome Mutations and Chromosome Disorders

1. Chromosome Mutations and Chromosome Disorders

2. What is this diagram called? A Karyotype

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

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

5. 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.

6. 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

7. Homologous chromosomes fail to separate Meiosis I: Nondisjunction Meiosis II 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

8. 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.

9. 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.