Errors in mitosis and meiosis Flashcards
What are the consequences of faulty meiosis?
Infertility
Miscarriages
What is non-disjunction?
Chromatids/chromosomes are not separated in anaphase
both move to one pole of cell
Chromosomes used for analysis come from what stage of the cell cycle?
Metaphase of mitosis
How are chromosomes visualised?
Stained
then looked at under microscope
What is a karyotype?
Information about the chromosomes present in the cell
any numerical or structural changes
How is a karyotype imaged?
Homologous chromosomes next to each other in pairs
How is a karyotype written?
Total number of chromosomes
sex chromosomes
any additional or missing chromosomes
commas in between, no spaces
What is trisomy?
Three copies of a particular chromosome instead of two
What is aneuploidy?
Abnormal number of chromosomes
What does mitotic non-disjunction produce?
Daughter cell with trisomy, two of them are identical
Daughter cell with monosomy
What is monosomy?
Only one copy of a particular chromosome instead of two
What happens to cells with monosomy?
Usually die
unless monosomy involves X chromosome
What is the outcome of mitotic non-disjunction in the first post-zygotic division
Daughter cell with trisomy survives
all cells from thereon have trisomy
What is the outcome of mitotic non-disjunction in the second post-zygotic division?
Daughter cell with normal number of chromosomes survives and divides
Daughter cell with trisomy survives and divides
What is the karyotype of mitotic non-disjunction in the second post-zygotic division?
46,N/47,N,+Z
mosaic karyotype
