ATI RN
Pediatric Genetic Disorders Questions
Question 1 of 5
One of the following is true about telomerase:
Correct Answer: D
Rationale: Telomeres consist of TTAGGG repeats throughout (D is true). Rationale: Telomerase uses an RNA template (not DNA, B false), extends the 3’ end (C misleading), and is active in cancer (A false). Activity decreases with age (E false). 'D' fits best.
Question 2 of 5
Trisomy 47,XYY is a syndrome with signs and symptoms that range from being barely noticeable to learning disabilities, speech delay, low muscle tone. How would you expect this syndrome to have occurred?
Correct Answer: D
Rationale: Paternal nondisjunction causes 47, XYY. Rationale: Nondisjunction in paternal meiosis II results in YY sperm (24, YY), fertilizing an X egg (23, X), yielding 47, XYY. Dispermy or endomitosis would yield triploidy or tetraploidy.
Question 3 of 5
A person whose karyotype is 45, XX, t(15q;21q). If she mates with a 46, XY normal individual. What is the possibility that they will have a zygote which will develop into Down syndrome? ('t' is translocation):
Correct Answer: A
Rationale: 1/6 (A) is correct. Rationale: Robertsonian t(15;21) carrier (45, XX) produces 6 gamete types: normal 15+21, t(15;21), 15, 21, null 15, null 21. With normal sperm (15+21+Y), only 21+t(15;21) yields 47, +21 (Down). 1/6 gametes result in trisomy 21.
Question 4 of 5
Chromosome 22 is:
Correct Answer: A
Rationale: Chromosome 22 is acrocentric, with a very short p-arm and centromere near one end. 'A' is correct. Rationale: Human acrocentric chromosomes (13, 14, 15, 21, 22) have nucleolar organizer regions on their p-arms; 22 fits this pattern, unlike metacentric (central centromere) or telocentric (end centromere).
Question 5 of 5
Which banding technique stains heterochromatin (dark) and euchromatin (light)?
Correct Answer: C
Rationale: G-banding (C) stains heterochromatin dark (G-positive) and euchromatin light. Rationale: Giemsa stains AT-rich, gene-poor heterochromatin dark, while GC-rich, gene-active euchromatin stays light, standard for karyotyping.