Mechanisms of Chromosome Abnormalities

Question 1

Alternate segregation

Answer 1

(balanced)

one normal daughter cell, one cell with a balanced rearrangement

Question 2

Adjacent 1

Answer 2

(Unbalanced) homologous centromeres separate to DIFFERENT daughter cells

Question 3

Adjacent 2

Answer 3

(Unbalanced) homologous centromeres pass to the SAMEdaughter cell

Question 4

Most common structural abnormality in the general population

Answer 4

Robertsonian translocation

Question 5

Most common Robertsonian translocation (75%)

Answer 5

rob(13;14)

Question 6

Pericentric inversion

Answer 6

Inverted region includes the centromere

Question 7

Paracentric inversion

Answer 7

Inverted region does not include the centromere

Question 8

The most common trisomy in products of conceptions (abortuses) is trisomy

Answer 8

16

Question 9

Velocardiofacial syndrome is also known as

Answer 9

DiGeorge (22q11.2 deletion)

Question 10

An odd number of crossovers in a PERIcentric inversion loop results in…

Answer 10

a normal chromatid, an inverted chromatid, 2 chromatids with duplication/deficiencies

Question 11

An odd number of crossovers in a PARAcentric inversion loop results in…

Answer 11

a normal chromatid, an inverted chromatid, an acentric fragment, a dicentric chromatid

Question 12

What’s the difference between a fragment and a marker chromosome?

Answer 12

Marker has a centromere

Question 13

Aneuploidy results from ___ which can occur in ____

Answer 13

nondisjunction; meiosis I, meiosis II, or mitosis

Question 14

The major cause of mosaic aneuploidy is ___

Answer 14

nondisjunction in mitosis