Chromosome abnormalities? help plz?

Question

Chromosome abnormalities arise during meiosis or mitosis?

Please help with the question, either by finding a diagram or explaining the process to me.
Thanks

Answer 1

More abnormalities arise during meiosis. During meiosis I there is a process called crossing over. It happens while the homologous pairs are synapsed. Some abnormalities that can happen at this time are:

1. nondisjunction - the chromosome pairs fail to separate properly after synapsis so the resulting cells have too many or too few chromosomes
See: http://www.altavista.com/image/results?itag=ody&q=nondisjunction&kgs=1&kls=0

2. unequal crossing over - when the chromatids trade segments, the segments may not be of equal length so the resulting chromatids may have duplicate copies of genes or be missing copies of genes.
See: http://www.cbs.dtu.dk/staff/dave/roanoke/genetics980225.html

Other abnormalities also occur, but the two listed above are somewhat common.

Answer 2

can occur in both processes...
but common during meiosis
non disjunction is a common process