Cytogenetics

Cytogenetics

Chromosome number changes
1. Polyploidy
  1. More than 2 sets of chromosomes
  2. Autopolyploids: the chromosome sets are all identical; all chromosomes are derived from the same species
  3. Many polyploids are sterile, due to problems with pairing and separation of homologous chromosomes in meiosis
  4. Allopolyploids: result of crosses between 2 or more (usually related) species
  5. Tissue specific polyploidy
    1. Endomitosis: sister chromatids separate but no cytokinesis occurs; results in tetraploid cells- liver and kidney cells
2. Aneuploidy
  1. Diploid genome which lacks a chromosome or has an extra chromosome
  2. Can be caused by meiotic nondisjunction
Autosomal Trisomies
Chromosome Structural Changes
1. Chromosome Identification: size, centromere position, banding patterns produced by different strains
2. Deletions: Two breaks in a chromosome. A small piece of chromosome is lost. The larger pieces rejoin
  1. Effects depend on size of deletion
  2. Intragenic deletions: deletions within a gene typically inactivate the gene - NULL mutation
  3. Multigenic deletions: involve deletions of 2 to thousands of genes - produce Deletion Syndromes
3. Duplications: Extra copy of gene or chromosomal region; duplicate regions can be located adjacent to each other, or one can be located in the normal location and the other in a novel location
  1. Extra regions can undergo gene mutation - opportunity for divergence in function
4. Inversions
5. Translocations
  1. Reciprocal Translocations
  2. Robertsonian Translocations
  3. Unidirectional Translocations
  4. Some translocations are associated with cancer

Next up

Description

Resource summary

Similar

	Created by clairegillian95 about 10 years ago