1. Chapter 8: Chromosome Mutations
*Chromosome mutations/aberrations
Variation in chromosome number:
*aneuploidy
*euploidy
*polyploidy

2. Homologous chromosomes: during anaphase I
Nondisjunction
Homologous chromosomes: during anaphase I
Sister chromatids: during anaphase II

3. Monosomy
*Condition in which one member of a chromosome pair is missing (2n-1)
In Drosophila:
Haplo-IV are monosomic for chromosome 4
*develop more slowly, reduced size, impaired viability
In Plants:
Maize, tobacco, evening primrose, Jimson weed
*Segmental deletions
*Cri-du-chat (46,5p-)

4. Trisomy
*Condition in which one chromosome is present in three copies (2n+1)
In Plants:
Jimson weed, rice
In Drosophila and humans:
Has severe effects, usually lethal
Exceptions:
Patau syndrome, 47,13+
Edwards syndrome, 47,18+

5. Down syndrome, 47,21+

6. 1) Addition of one or more sets of chromosomes (replication)
Polyploidy
1) Addition of one or more sets of chromosomes (replication)
2) Combination of chromosome sets from different species

7. Polyploidy Autopolyploidy Arise in several ways:
*failure of all chromosomes to segregate during meiosis
*two sperm may fertilize an ovum
*experimentation
The benefits of autopolyploid breeding:
increased size of plant organs- roots, leaves, flowers fruits, seeds

8. Polyploidy
Allopolyploidy

9. Variations in Chromosome Structure
Deletions

10. Variations in Chromosome Structure
Duplications A B C D
Crossover:
Due to unequal crossing over:

11. Evolution of hemoglobin genes

12. Variations in Chromosome Structure
Inversions
*Paracentric
*Pericentric

13. Variations in Chromosome Structure
Translocation

14. Variations in Chromosome Structure
Translocation – unbalanced gametes are produced