Brainscape's Knowledge GenomeTM

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


See full index

MoMF > Chromosomes and Chromosomal Abnormalities > Flashcards

Chromosomes and Chromosomal Abnormalities Flashcards

1
Q

3 types of Chromosomal structure

A

1) Metacentric
2) Submetacentric (p and q subunits)
3) Acrocentric (entirely below central line)

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

3 types of Chromosomal structure

A

1) Metacentric
2) Submetacentric (p and q subunits)
3) Acrocentric (entirely below central line)

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

Metaphase chromosomal structure

A

Stains show compaction

*there are different bands/stains per stage (ie: prophase has a lot)

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

Giemsa stain

A

Imaging chromosomal banding pattern

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

Dark bands

A

gene poor

heterochromatin

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

Light bands

A

gene rich- 50+ genes per band

euchromatin

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

How do you profile chromosomes?

A

1) Size
2) Centromere position
3) Banding pattern

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

When is profiling chromosomes necessary?

A

1) Problems in early growth and development
2) Stillbirth and neonatal death
3) Infertility
4) Family History
5) Neoplasia
6) Pregnancy for mother of advanced maternal age

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

Tissue sources for profiling chromosomes

A 
Blood (somatic cells)
Cheek Cells (somatic cells)

Amniocentesis or CVS (prenatal screening)

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

Chromosomal analysis- duration?

A

Grow cells and stain DNA

Few days in between taking sample and getting diagnostic

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

Polyploidy

A

Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes

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

Aneuploidy

A

presence of an abnormal number of chromosomes in a cell, for example when having 45 or 47 chromosomes when 46 is expected in a human cell.

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

Ploidy

A

the number of sets of chromosomes in a cell, or in the cells of an organism.

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

Euploidy

A

Euploidy is the state of a cell or organism having the same number of each homologous chromosome

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

Consequences of meiotic nondisjunction

A

trisomy and monosomy

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

Origins of nondisjunction

A

associated more with oocytes than spermatocytes

can be traces back to meiosis

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

Nondisjunction and maternal age

A

rate of nondisjunction pretty steady up until 34-35 with rise increase after that

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

ACOG

A

practice guideline on prenatal aneuploidy screening and maternal age

maternal age independent- b/c improved low risk/noninvasive screening methods

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

ACMG

A

Recommended for trisomy 13, 18, 21
can be offered for sex chromosome aneuploidy and possibly clinically relevant deletions

complications:
maternal weight
maternal aneuploidy 
organ transplant 
gestational stage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Chromosomes with viable aneuploidy

A

13, 18, 21, X, Y

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

Where do most nondisjunction events trace back to?

A

Meiosis 1 in mothe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which nondisjunction event potentially results in the least clinically severe outcome for resulting conceptions or fetuses?

A

post-zygotic mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Difference between triploid and trisomy?

A

triploid- 3N

trisomy- 2N + 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Mitotic- post zygotic- nondisjunction

A

Results in number of normal cells and few trisomic and monosomic cells

The monosomic cells have a hard time surviving so die out

The trisomic (aneuploid) cells only 25% of total cell volume and thus less severe

Phenotype also depends on which cells have the trisomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

FISH

A

hybridization using a probe with a complimentary sequence to chromosome you care about

easier to do after baby is born

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Microarrays

A

each spot represents a unique part of the genome
normal reference- green
fetal- red

isolate DNA from each sample
label DNA with fluorescent tags

Mix samples and hybridize to the microarray

Rinse away unbound material; scan with a laser microscope

~comparing relative quantities
~this lets you scan the entire genome at once and look for changes in copy number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What can a karyotype do?

A

> 7-10 million bp

Detects copy number variation and positioning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What can a microarray do?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Trisomy 18

A

Edwards syndrome

clench fist
rocker bottom left foot
low set, malformed ears
mental retardation and cardiac malformations

only 5% survive birth, only 10% of those live past 2 years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Trisomy 13

A

Patau Syndrome

Bilateral cleft lip
Polydactyl
midline defects
heart, nervous system, growth malformations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Trisomy 21

A

Downs Syndrome
1 in 800

Hypotonia- low muscle tone
Short stature
open mouth with large tongue
Leukemia risk/ AD early onset

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Robertsonian Translocation

A

46, XY, t(14;21), +21
46, XY, -14, t(14;21)

-as long as you have 2 copies of each you can by asymptomatic but at risk of passing it to child

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Form of trisomy 21 with the highest risk of reoccurrence in subsequent pregnancy?

A

Robertsonian Trisomy 21

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Dosage compensation

A

Males only have 1 X chromosome and females have 2….body tried to make it so that the double X acts like a single X –> leads to x inactivation in mammals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

X inactivation

A

Doesn’t matter how many X always shutting it down
so if female has 3 X, 2 are shut down
if make has 2 X, 1 is shut down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Escape from X inactivation

A

some genes that are still expressed in an inactivated X chromosome (mainly a part of the p section of the chromosome)

clincal phenotype is generally milder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Monosomy X

A

Turner Syndrome

Diagnosis at birth or puberty 
Webbed neck
Short stature 
lymph edema 
amenhorrea- absence of period 
infertility 
normal intelligence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Trisomy XXY

A

Klinefelter Syndrome

2nd X goes thru X-inactivation but still some phenotype is expressed

Infertility
Hypogonadism
Gynecomastia- male breasts
Behavioral difficulties: learning, social, IQ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Paracentric inversions

A

pArA: an inversion that is away from centromere

*Inversions usually do not cause any abnormalities in carriers as long as the rearrangement is balanced with no extra or missing DNA

40
Q

Pericentric Inversions

A

perI- inversion includes chromosome

41
Q

Consequences of an inversion

A

Paracentric: Unbalanced offspring and genome instability
^chromosome has 2 centromeres and if spindle tries attaching at 2 spots, can rip the chromosome

Pericentric: Unbalanced offspring

42
Q

Spectral Karyotyping (SKY)

A

Individual probe sets labelled in 24 different colors for each unique chromosome

Makes it easier to determine origin of any extra DNA

Especially useful to look for translocations..normal abnormalities would be obvious in normal G-banded karyotype

only use if expect substantial changes in # and structure

43
Q

Reciprocal translocation

A

2 parts are swapped–> balanced translocation (# is still the same)

vast number are not going to create a fusion protein –> worry is at meiosis how will they be passed on

44
Q

Chronic Myelogenous Leukemia

A

ie of reciprocal translocation

the t(9;22) gene acts like a kinase at the wrong times and places –> causes leukemia

46,XX, t(9;22)(q34;q11)

45
Q

Principles of X inactivation

A

1) normally choice of Xi is random

2) choice may become non-random if one of the X chromosomes is severely defected in some way

46
Q

What happens if one X chromosome is defective?

A

1) try to preserve the activity of one X equivalent

2) (if possible) preserve autosomal sequences

47
Q

Unbalanced rearrangement

A

isochromosome- either 2 p arms or 2 q arms on the same chromosome thru deletion –> crossing over –> ring

48
Q

Unbalanced rearrangement - Turner’s Syndrome

A

45, XO = 46, XX, i(Xq)

49
Q

5p15 deletion

A

Cri du chat

cry that sounds like a cat
mental retardation
microcephaly- abnormal head

50
Q

Metaphase chromosomal structure

A

Stains show compaction

*there are different bands/stains per stage (ie: prophase has a lot)

51
Q

Giemsa stain

A

Imaging chromosomal banding pattern

52
Q

Dark bands

A

gene poor

heterochromatin

53
Q

Light bands

A

gene rich- 50+ genes per band

euchromatin

54
Q

How do you profile chromosomes?

A

1) Size
2) Centromere position
3) Banding pattern

55
Q

When is profiling chromosomes necessary?

A

1) Problems in early growth and development
2) Stillbirth and neonatal death
3) Infertility
4) Family History
5) Neoplasia
6) Pregnancy for mother of advanced maternal age

56
Q

Tissue sources for profiling chromosomes

A 
Blood (somatic cells)
Cheek Cells (somatic cells)

Amniocentesis or CVS (prenatal screening)

57
Q

Chromosomal analysis- duration?

A

Grow cells and stain DNA

Few days in between taking sample and getting diagnostic

58
Q

Polyploidy

A

Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes

59
Q

Aneuploidy

A

presence of an abnormal number of chromosomes in a cell, for example when having 45 or 47 chromosomes when 46 is expected in a human cell.

60
Q

Ploidy

A

the number of sets of chromosomes in a cell, or in the cells of an organism.

61
Q

Euploidy

A

Euploidy is the state of a cell or organism having the same number of each homologous chromosome

62
Q

Consequences of meiotic nondisjunction

A

trisomy and monosomy

63
Q

Origins of nondisjunction

A

associated more with oocytes than spermatocytes

can be traces back to meiosis

64
Q

Nondisjunction and maternal age

A

rate of nondisjunction pretty steady up until 34-35 with rise increase after that

65
Q

ACOG

A

practice guideline on prenatal aneuploidy screening and maternal age

maternal age independent- b/c improved low risk/noninvasive screening methods

66
Q

ACMG

A

Recommended for trisomy 13, 18, 21
can be offered for sex chromosome aneuploidy and possibly clinically relevant deletions

complications:
maternal weight
maternal aneuploidy 
organ transplant 
gestational stage
67
Q

Chromosomes with viable aneuploidy

A

13, 18, 21, X, Y

68
Q

Where do most nondisjunction events trace back to?

A

Meiosis 1 in mother

69
Q

Which nondisjunction event potentially results in the least clinically severe outcome for resulting conceptions or fetuses?

A

post-zygotic mitosis

70
Q

Difference between triploid and trisomy?

A

triploid- 3N

trisomy- 2N + 1

71
Q

Mitotic- post zygotic- nondisjunction

A

Results in number of normal cells and few trisomic and monosomic cells

The monosomic cells have a hard time surviving so die out

The trisomic (aneuploid) cells only 25% of total cell volume and thus less severe

Phenotype also depends on which cells have the trisomy

72
Q

FISH

A

hybridization using a probe with a complimentary sequence to chromosome you care about

easier to do after baby is born

73
Q

Microarrays

A

each spot represents a unique part of the genome
normal reference- green
fetal- red

isolate DNA from each sample
label DNA with fluorescent tags

Mix samples and hybridize to the microarray

Rinse away unbound material; scan with a laser microscope

~comparing relative quantities
~this lets you scan the entire genome at once and look for changes in copy number

74
Q

What can a karyotype do?

A

> 7-10 million bp

Detects copy number variation and positioning

75
Q

What can a microarray do?

A
76
Q

Trisomy 18

A

Edwards syndrome

clench fist
rocker bottom left foot
low set, malformed ears
mental retardation and cardiac malformations

only 5% survive birth, only 10% of those live past 2 years

77
Q

Trisomy 13

A

Patau Syndrome

Bilateral cleft lip
Polydactyl
midline defects
heart, nervous system, growth malformations

78
Q

Trisomy 21

A

Downs Syndrome
1 in 800

Hypotonia- low muscle tone
Short stature
open mouth with large tongue
Leukemia risk/ AD early onset

79
Q

Robertsonian Translocation

A

46, XY, t(14;21), +21
46, XY, -14, t(14;21)

-as long as you have 2 copies of each you can by asymptomatic but at risk of passing it to child

80
Q

Form of trisomy 21 with the highest risk of reoccurrence in subsequent pregnancy?

A

Robertsonian Trisomy 21

81
Q

Dosage compensation

A

Males only have 1 X chromosome and females have 2….body tried to make it so that the double X acts like a single X –> leads to x inactivation in mammals

82
Q

X inactivation

A

Doesn’t matter how many X always shutting it down
so if female has 3 X, 2 are shut down
if make has 2 X, 1 is shut down

83
Q

Escape from X inactivation

A

some genes that are still expressed in an inactivated X chromosome (mainly a part of the p section of the chromosome)

clincal phenotype is generally milder

84
Q

Monosomy X

A

Turner Syndrome

Diagnosis at birth or puberty 
Webbed neck
Short stature 
lymph edema 
amenhorrea- absence of period 
infertility 
normal intelligence
85
Q

Trisomy XXY

A

Klinefelter Syndrome

2nd X goes thru X-inactivation but still some phenotype is expressed

Infertility
Hypogonadism
Gynecomastia- male breasts
Behavioral difficulties: learning, social, IQ

86
Q

Paracentric inversions

A

pArA: an inversion that is away from centromere

*Inversions usually do not cause any abnormalities in carriers as long as the rearrangement is balanced with no extra or missing DNA

87
Q

Pericentric Inversions

A

perI- inversion includes chromosome

88
Q

Consequences of an inversion

A

Paracentric: Unbalanced offspring and genome instability
^chromosome has 2 centromeres and if spindle tries attaching at 2 spots, can rip the chromosome

Pericentric: Unbalanced offspring

89
Q

Spectral Karyotyping (SKY)

A

Individual probe sets labelled in 24 different colors for each unique chromosome

Makes it easier to determine origin of any extra DNA

Especially useful to look for translocations..normal abnormalities would be obvious in normal G-banded karyotype

only use if expect substantial changes in # and structure

90
Q

Reciprocal translocation

A

2 parts are swapped–> balanced translocation (# is still the same)

vast number are not going to create a fusion protein –> worry is at meiosis how will they be passed on

91
Q

Chronic Myelogenous Leukemia

A

ie of reciprocal translocation

the t(9;22) gene acts like a kinase at the wrong times and places –> causes leukemia

46,XX, t(9;22)(q34;q11)

92
Q

Principles of X inactivation

A

1) normally choice of Xi is random

2) choice may become non-random if one of the X chromosomes is severely defected in some way

93
Q

What happens if one X chromosome is defective?

A

1) try to preserve the activity of one X equivalent

2) (if possible) preserve autosomal sequences

94
Q

Unbalanced rearrangement

A

isochromosome- either 2 p arms or 2 q arms on the same chromosome thru deletion –> crossing over –> ring

95
Q

Unbalanced rearrangement - Turner’s Syndrome

A

45, XO = 46, XX, i(Xq)

96
Q

5p15 deletion

A

Cri du chat

cry that sounds like a cat
mental retardation
microcephaly- abnormal head

MoMF (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions