Cytogenetics 1 & 2

Question 1

What letter signifies the short arm of a chromosome?

Answer 1

p

Question 2

What letter signifies the long arm of a chromosome?

Answer 2

q

Question 3

What is a metacentric chromosome?

Answer 3

The short and long arms are of equal size

Question 4

What is a sub-metacentric chromosome?

Answer 4

the short and long arm are of unequal size

Question 5

What is an Acrocentric chromosome?

Answer 5

The short arm is very small and close to the centromere

Question 6

How is the “banding” pattern achieved in G-banding?

Answer 6

Trypsin treatment and staining with Giemsa

Question 7

What mutation results in Turner syndrome?

Answer 7

One X chromosome missing

Question 8

What mutation results in Klinefelter syndrome?

Answer 8

XXY

Question 9

What mutation results in cri-du-chat syndrome?

Answer 9

Deletion in the short arm of chromosome 5

Question 10

What is the most common cause of triploidy?

Answer 10

An ovum is fertilized by two sperm

Question 11

When does nondisjunction most often occur?

Answer 11

Meiosis I of oogenesis

-associated with advanced maternal age

Question 12

What is mosaicism?

Answer 12

The mixture of two or more cell lines in an individual

Question 13

What are the three types of mosaicism?

Answer 13

1) Generalized mosaicism
2) Confined placental mosaicism
3) Fetal mosaicism

Question 14

What are they types of structural chromosomal abnormalities?

Answer 14

• Deletions
• Duplications
• Translocations
• Rings
• Inversions

Question 15

What is the purpose of performing a microarray on a patient?

Answer 15

to determine whether the patient is missing or has extra chromosomal material

Question 16

What is a comparative genomic hybridization array? (aCGH)

Answer 16

• microarray
• looks for DNA copy-number variations
• Checks for gains or losses of DNA

Question 17

What are the limits of G-Banding analysis?

Answer 17

Can only have a resolution of 4-5Mb. Solve with aCGH

Question 18

What are the limitations of Microarray Methodology?

Answer 18

• Cannot detect balanced rearrangements (Translocations, inversions, insertions)
• Does not provide information regarding location of additional copy
• Solve with FISH

Question 19

What can FISH do?

Answer 19

identify specific chromosomal regions that have been deleted or duplicated (Location)

Question 20

What mutation results in Wolf-Hirshhorn syndrome?

Answer 20

A terminal deletion on the short arm of chromosome 4

Question 21

What mutation results in Velocardiofacial and Di-George Syndrome?

Answer 21

Microdeletion on the long arm of chromosome 22

Question 22

What are the typical behaviors of someone with wiliams beuren syndrome?

Answer 22

• overfriendliness

- ADD

Question 23

How do Robertsonian translocations originate?

Answer 23

joining of the long arms of acrocentric chromosomes: 13, 14, 15, 21, and 22