Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CMD Block 2 > Chromosome Number > Flashcards

Chromosome Number Flashcards

1
Q

Why does Trisomy 21 occur more frequently in young mothers?

A

Young mothers have more babies than older mothers– even though the risk is smaller DS has a higher prevalence in this age group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What form of chromosomes are targeted in a slide preparation for FISH?

A

Metaphase or interphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Test that applies a specific probe in order to determine the number of copies of chromosome present

A

FISH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does a fluorescent probe join DNA?

A

DNA is denatured and hybridized with complementary probe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

FISH analysis can determine…

A

if the probed chromosomes are numerically correct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

FISH analysis cannot determine…

A

if anything is wrong with unprobed regions of the genome nor if mosaicism is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mitotic nondisjunction creates presence of more than one cell line

A

Mosaicism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Mosaicism

A

Mitotic nondisjunction creates presence of more than one cell line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the most plausible cause of trisomy mosaicism?

A

Normal cell line at conception, then a nondisjunction event gave rise to an additional chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Always results from post-zygotic error

A

mosaicism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Possible locations of mosaicism

A

Generalized, confined to placenta, confined to fetus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What limits diagnosis of mosaicism?

A

Limitations in sampling, which includes tissue specific differences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Level of mosaicism correlates with

A

phenotypic severity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which tissues often contain trisomic cells?

A

Kidney, placenta, gut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Nondisjunction

A

error in cell division in which improper segregation results in abn chromosome number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Error in this leads to mosaicism

A

mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which portion of cell division has an age-related risk of maternal nondisjunction?

A

Meiosis I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How many normal daughter cells result for meiosis I nondisjunction?

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How many normal daughter cells result for meiosis II nondisjunction?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Euploid

A

normal chromosome number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Aneuploidy

A

abnormal chromosome number

22
Q

Polyploidy

A

Additional set of chromosomes

23
Q

Most common cause of triploidy

A

Dispermy

24
Q

Cause of tetraploidy

A

Failure of cell division

25
Q

T/F: ALL monosomies are lethal

A

T

26
Q

Trisomies than can result in a live birth

A
  1. 18, 21, Sex chromosomes
27
Q

How does mosaicism affect the severity of a trisomy?

A

The normal chromosomes make the phenotype less severe

28
Q

Including preimplantation errors, how many fertilized eggs spontaneously abort?

A

50%

29
Q

Common sex chromosome abnormality, frequently results in spontaneous ab

A

45, X

30
Q

Why do monosonies reflect such a small portion of observed spontaneous abortions?

A

They abort so early detection is uncommon.

31
Q

Why does the risk of a trisomy 21 offspring decrease as the pregnancy develops?

A

Spontaneous abortions

32
Q

Phenotypic result of 47,XXX 47,XXY or 47XYY

A

Pretty minor problems with a normal lifespan

33
Q

Common phenotypic characteristics of Down Syndrome

A

heart defects, simian crease, MR, duodenal atresia (obstruction)

34
Q

Most common cause of trisomy 21?

A

Meiosis I nondisjunction

35
Q

Trisomy 21 mosaicism is (more/less) severe than a purely trisomic genome

A

Less

36
Q

Common phenotypic characteristics of trisomy 18

A

Clutched hands, rocker bottom feet, MR, heart defect

37
Q

Common phenotypic characteristics of trisomy 13

A

Midline defects (cleft palate, eyes close-set or fused), forebrain fails to form lobes, MR, abdominal defects, polydactyly

38
Q

Common causes of trisomy 13

A

Maternal meiosis nondisjunction > Robertsonian

39
Q

Why are extra copies of X tolerated?

A

All but one is inactivated

40
Q

Common phenotypic characteristics of Turner Syndrome

A

Ovarian dysgenesis, amenorrhea, infertility, abn lymphatics, no MR, neck webbing

41
Q

Result of X chromosome nullisomy

A

Non-viable

42
Q

Only tolerated monosomic condition

A

45,X (still has a high rate of miscarriage)

43
Q

Most likely cause of Turner’s Syndrome.

A

Paternal meiotic nondisjunction (no relation to advanced maternal age)

44
Q

What may contribute to the high survival rate of Turner’s Syndrome genotype?

A

Mosaicism

45
Q

Possible genotypes of mosaic Turner’s Syndrome

A

45,x/47,XXX or 45,X/46,XX or 45,X/46,XY

46
Q

Genotype of Klinefelter’s Syndrome

A

47,XXY

47
Q

Common causes of Klinefelter’s Syndrome

A

50% Paternal nondisjunction, 50% age-related maternal nondisjunction

48
Q

Common phenotypes in Klinefelter’s Syndrome

A

hypogonadism, long extremities, reduced IQ, gynecomastia

49
Q

Most common cause of Triple X Syndrome

A

Maternal nondisjunction, related to age

50
Q

Phenotypic results of Triple X Syndrome

A

essentially normal

51
Q

Cause of 47,XXY Syndrome

A

Paternal meiosis II nondisjunction without age effect

CMD Block 2 (38 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions