Chromosomal Abnormalities Flashcards
1
Q
- incorrect number of chromosomes
A
chromosomal abnormalities
2
Q
nondisjunction
A
- chromosomes dont separate properly during meiosis (homologous during meiosis 1, sister chromatids fail to separate during meiosis 2- too many or too few chromosomes)
- problems with meiotic spindle cause errors in daughter cells
- baby has wrong chromosome number
- TRISOMY: cells have 3 copies of a chromosome
- MONOSOMY: cells have 1 copy of a chromosome
3
Q
breakage of chromosomes
A
- deletion: loss of a chromosomal segment
- duplication: repeat a segment
- inversion: reverses a segment
- translocation: move segment from one chromosome to another
4
Q
Human chromosome diseases
A
- high frequency in humans
- most embryos are spontaneously aborted, alterations are too disastrous, developmental problems result from biochemical imbalances (hormones and transcription factors)
5
Q
Trisomy 21
A
- Down syndrome
- chromosome 21 is the smallest human chromosome
- frequency of Down syndrome is relative to the mother’s age
6
Q
XXY
A
kleinfelter’s syndrome male
- male sex sterile organs
- feminine characteristics: some breast development and lack of facial hair
- tall and normal intelligence
7
Q
XXX
A
trisomy x female
- produces healthy females because of Barr bodies (where all but one x chromosome is inactivated)
8
Q
XO
A
Turner syndrome female
- monosomy X or X0
- webbed neck, short stature, sterile
9
Q
XYY
A
Jacob syndrome’s male
- extra Y chromsome: slightly taller than average
- more active
- normal intelligence with slight learning disabilities
- delayed emotional maturity
- normal sexual development
10
Q
Genomic Imprinting
A
- phenotypic effects on some mammalian genes depend on whether or not they were inherited from the mother or father (imprinting)
11
Q
Prader-Willi syndrome
A
- characterized by mental retardation, obesity, short-stature, and unusually small hands and feet (these individuals inherit the abnormal chromosome from their father)
12
Q
Angelman Syndrome
A
- exhibit spontaneous laughter, jerky movements, and other motor/mental symptoms (inherited from the mother)
