Errors in Meiosis and X-inactivation Flashcards
What is Aneuploidy?
Abnormal number of a particular chromosome
What is Down Syndrome?
Type of Aneuploidy
Extra chromosome 21
More commons in mothers who give birth >45
What is Nondisjunction?
Failure of chromosomes to seperate properly in meiosis
Can occur during meiosis I or meiosis II
What is Klinefelter Syndrome (XXY)?
An individual has an extra X chromosome, phenotypically male but has a number of female features e.g. breast tissue
What is Turner Syndrome?
Only one X chromosome no Y, no second X, phenotypically female, individuals are quite short, small finger nails. It matters which parent passed the X chromosome down
What is Polyploidy?
The possession of multiple sets of chromosomes, offspring with polyploid karyotypes may be viable and self-fertile
What is Karpechenko 1928?
Creating a polyploid 4n raddage - raddish and cabbage - created a sterile offspring
What is inversion?
An inversion reverses a segment within a chromosome
What is a duplication?
A duplication repeats a segment in a chromosome
What is translocation?
A translocation moves a segment from one chromosome to a non homologous chromosome
What is deletion?
Deletion removes a chromosomal segment
What is Philadelphia Translocation?
translocation of (9;22), 95% of chronic luchemia patients, piece of chromosome 9 put on chromosome 22, 22 put on a 9, leads to genes being on all the time (regulation fails)
What is X-Inactivation?
Turn off/shut down, large parts of one of the X chromosomes in sex cells, could lead to mosaic patterning
