MCM 2-30 Cytogenics Introduction Flashcards Preview

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Flashcards in MCM 2-30 Cytogenics Introduction Deck (18)
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1

Fetal Loss Statistics

___ of recognize fertilizations fail

____ in first trimester

___ due to chromosome abnormalities

_____ of chromosomal losses are autosomal trisomies

most fertilizations fail
15% of recognized fertilizations fail
80% in first trimester

60% due to chromosome abnormalities

52% are autosomal trisomies

2

triploidy has how many chromosomes?

69, 3 of each

3

ploidy =

euploid =
diploid =
triploid =
tetraploid =

how many sets of chromosomes we have

euploid - 1 set (1n)
diploid (2n)
triploid (3n)
tetraploid (4n)

4

aneuploid?

not a full multiple of 23

ex) monosomy, only 1
or trisomy (3 instead of 2)

5

when can nondisjunction occur?

in first cell division

6

Meiotic nondisjunction; anaphase I nondisjunction can lead to

two disomic/ n+1 games, two monosomic/ n-1 gametes

which can lead to

trisomy and monoloid zygotes

7

nondisjunction in meiosis 2 will lead to

2 normal, 1 disomic (n+1) and 1 nullsomic (n-1)

8

correct way to write a female with extra chromosome 13?

male missing a chromosome 8?

47,XX,+13

45,XY,-8

9

aneuploidy can be caused by nondisjunction in

mitosis or meiosis

10

Mosaicism

examples?

how is it inherited?

presence of at least 2 different cell lines with at least one clear variation between them

cell lines with numerical changes 45,X and 46,XX

cell lines with structural change - one cell line with translocation that doesnt occur in the other

mosiacism is not inherited, only acquired

11

viable autosomal trisomies and features of each

Downs syndrome - trisomy 21

Patau Syndrome - Trisomy 13 (cleft lip and palate)

Edwards Syndrome - trisomy 18. Worst prognosis, rocker feet

12

Sex chromosome Aneuploidies (4)

Klinefelter Syndrome - 47,XXY

XYY male

XXX female

turner Syndrome: 45,X

13

sex determination is based on..

genes on X, Y, and autosome chromosomes

14

TDF/SRY

SRY = sex determining region on the Y chromosome encodes testes determining factor

Females lack TDF/SRY - formation of ovary, proliferation of mullerian and regresson of wolffian ducts

males have TDF/SRY - formation of testes which inhibit/degrade mullerian ducts and product testosterone to proliferate wolffian ducts

15

appearance of XX female somatic cells? XXX?

XX female will have a single bar body in her cells

XXX femlaes will have two barr bodies

16

X inactivation is random but

once established, is not reversible in SOMATIC tissues

17

females are mosaics for..

heterozygous traits

18

what causes Aneuploidy?

ex?

gain or loss of a chromosomes equaling less than one complete complement

ex) trisomy and monosomy

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