Chromosomal abnormalities Flashcards
Chromatin is switched between active and inactive by ……. ……..
Epigenetic modfication
DNA methylation and histone deacylation, activates or deactivates DNA?
Deactivates DNA
What is the name of the long and short arms on chromosomes?
Long arm- Q arm
Short arm - P arm
When staining via G-banding; What do the light and dark bands represent?
Dark bands are AT rich meaning gene poor
Light bands are GC rich meaning gene rich
If you received a chromosome report saying 47, XX, +21. What does it mean?
A female with 47 chromosomes, extra chromosome 21 (trisomy 21)
Which holds a higher risk of miscarriage chorionic villus sampling or aminiocentesis?
Chorionic villus sampling
What is aneuploidy?
Aneuploidy is the loss or gain of whole chromosomes.
Trisomy 21 results in which syndrome?
Down’s syndrome
Trisomy 13 results in which syndrome?
Patau’s syndrome
Monosomy of the X chromosome results in which syndrome?
Turner’s syndrome
What is polyploidy?
It is the gain of a whole set of chromosomes. It is caused by polyspermy.
What are the possible causes of aneuploidy? (2)
- Originates from non-disjunction at one of the meiotic cell divisions
- Can occur during mitotic cell division leading to mosaicism
What is anaphase lag?
Chromosomes are “left-behind” at cell division because of defects in spindle function
What is the purpose of X inactivation?
It ensures individuals have the same X chromosome complement active
If centromere is found in the middle of the chromosome the chromosome is said to be ……..
Metacentric
