Chromosomal disorders overview Flashcards
What are chromosomes?
Structures within cells that contains a person’s genes
What is the typical number of chromosomes?
- 46 (23 pairs)
2. One set from egg, one set from sperm
What are the first 22 pairs called? What are the final pair called?
22: Autosomes
Final: sex chromosomes
How are chromosomes studied? (2)
- Karyotype (image of all 46 chromosomes to identify abnormalities
- Newer: compare patient’s DNA to a typical DNA sample eg. prenatal testing
Why do chromosomal disorders occur?
Changes in either the number or structure of the chromosomes
How can the number of chromosomes be affected? (2)
- Missing one from a pair = monosomy
2. Has more than two chromsomes = trisomy
How can the structure of chromosomes be affected?
Material in an individual chromosome is disrupted or rearranged
Give 5 types of structural changes in chromosomes
- Deletion
- Duplication
- Translocation
- Rings
- Inversions
What is deletion?
Portion of the chromosome is missing or deleted
What is duplication?
Portion of the chromosome is duplicated - resulting in extra genetic material
What is translocation?
Portion of the chromosome is transferred to another
What are the 2 types of translocation?
Reciprocal: segments from two different chromosomes exchanged
Robertsonian: entire chromosome has attached to another at the centromere
What are rings?
Portion of the chromosome has broken off and formed a ring
What are inversions?
Portion of the chromosome has broken off, turned upside down and reattached
Genetic material is inverted
What are two types of cell division?
Meiosis
Mitosis
