Cytogenetics

Question 1

constitutional abnormalities

Answer 1

present in the conceptus and arise in the zygote, or very soon after formation of zygote (always present at birth)

Question 2

chromosomal abnormalities account for _

Answer 2

0.7% of live births

Question 3

numerical chromosomal errors

Answer 3

affect the entire chromosome –> additional haploid sets, aneuploidy

Question 4

structural errors in chromosome

Answer 4

occur within chromosome –> duplications or deletions

Question 5

entire karyotype is triploidy

Answer 5

caused by a diploid sperm or egg or being fertilized by two sperm; results in 69 chromosomes

Question 6

edwards syndrome

Answer 6

trisomy 18; an aneuploidy

Question 7

Turner syndrome

Answer 7

monosomy X (45, X)

Question 8

cri du chat syndrome

Answer 8

terminal deletion in chromosome 5 (missing p arm)

Question 9

prader-willi syndrome

Answer 9

deletion within a chromosome (interstitial deletion)

Question 10

Robertsonian translocation

Answer 10

translocation between two acrocentrics with fusion at or near the centromeres

Question 11

How many normal acrocentrics are there?

Answer 11

5 - chromosomes 13, 14, 15, 21, 22 (also Y chromosome)

Question 12

metacentric

Answer 12

both arms the same length; centromere in middle

Question 13

acrocentric

Answer 13

centromere is located very close to the p arm telomere; the p arm is only satellite DNA

Question 14

Robertsonian translocations are termed _

Answer 14

derivatives (der) because the acrocentric fusion will be deleted so even though it is technically a translocation, there is no second chromosome to say it was a translocation

Question 15

What happens when a father with a balanced translocation reproduces?

Answer 15

the child with have partial trisomy and partial monosomy

Question 16

aneuploidies arise from _

Answer 16

nondisjunction in meiosis I or meiosis II

Question 17

mosaics arise from _

Answer 17

nondisjunctions in mitosis (post-zygotically)