Chromosomal Abnormalities

Question 1

• incorrect number of chromosomes

Answer 1

chromosomal abnormalities

Question 2

nondisjunction

Answer 2

• 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

Question 3

breakage of chromosomes

Answer 3

• deletion: loss of a chromosomal segment
• duplication: repeat a segment
• inversion: reverses a segment
• translocation: move segment from one chromosome to another

Question 4

Human chromosome diseases

Answer 4

• high frequency in humans
• most embryos are spontaneously aborted, alterations are too disastrous, developmental problems result from biochemical imbalances (hormones and transcription factors)

Question 5

Trisomy 21

Answer 5

• Down syndrome
• chromosome 21 is the smallest human chromosome
• frequency of Down syndrome is relative to the mother’s age

Question 6

XXY

Answer 6

kleinfelter’s syndrome male

• male sex sterile organs
• feminine characteristics: some breast development and lack of facial hair
• tall and normal intelligence

Question 7

XXX

Answer 7

trisomy x female

• produces healthy females because of Barr bodies (where all but one x chromosome is inactivated)

Question 8

XO

Answer 8

Turner syndrome female

• monosomy X or X0
• webbed neck, short stature, sterile

Question 9

XYY

Answer 9

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

Question 10

Genomic Imprinting

Answer 10

• phenotypic effects on some mammalian genes depend on whether or not they were inherited from the mother or father (imprinting)

Question 11

Prader-Willi syndrome

Answer 11

• characterized by mental retardation, obesity, short-stature, and unusually small hands and feet (these individuals inherit the abnormal chromosome from their father)

Question 12

Angelman Syndrome

Answer 12

• exhibit spontaneous laughter, jerky movements, and other motor/mental symptoms (inherited from the mother)