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Cytogenetics > Lesson 4 : CHROMOSOMES > Flashcards

Lesson 4 : CHROMOSOMES Flashcards

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1
Q

Primarily consist of DNA and protein.

A

CHROMOSOMES

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2
Q

Essential parts of Chromosomes

A

■ Telomeres
■ Origins of replication sites
■ Centromere

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3
Q

Largest constriction of the chromosome and where spindle fibers attach.

A

CENTROMERE

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4
Q

Bases that form the centromere are repeats of a

A

171-base DNA sequence

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5
Q

_______ is passed to next generation.

A

CENP-A

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6
Q

Chromosome region between the centromere and telomeres.

A

SUBTELOMERE

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7
Q

Subtelomere consists of ____ to ____ bases.

A

8000 to 300,000

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8
Q

Subtelomere contains at least ____ protein-encoding genes. About 50% are multigene families that include _______.

A

500
pseudogenes

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9
Q

Define KARYOTYPE

A

● Chromosome chart.
● Major clinical tool.
● Displays chromosomes arranged by size and structure.

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10
Q

Humans have ___ chromosome types

_____ are numbered 1-22 by size
______ are X and Y

A

Humans have 24 chromosome
types.

■ Autosomes are numbered 1-22 by size
■ Sex chromosomes are X and Y

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11
Q

Karyotype Benefits

A

● Confirm a clinical diagnosis.
● Reveal effects of environmental toxins.
● Clarify evolutionary relationships.

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12
Q

CENTROMERE POSITIONS

A

● Telocentric - At the tip.
● Acrocentric - Close to center.
● Submetacentric - Off-center.
● Metacentric - At center.

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13
Q

○ Fetal tissue
○ Adult tissue

A

○ Fetal tissue
■ Amniocentesis
■ Chorionic villi sampling
■ Fetal cell sorting
■ Chromosome microarray analysis

○ Adult tissue
■ White blood cells
■ Skin-like cells from cheek swab

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14
Q

Chromosomes are extracted, then stained with a combination of _________ and _______

A

dyes and DNA probes

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15
Q

_________ detects about ______ of the more than ______ known chromosomal and
biochemical problems.

A

AMNIOCENTESIS
1000
5000

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16
Q

In Amniocentesis Ultrasound is used to ___________.

A

follow the needle’s movement

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17
Q

Define CHORIONIC VILLUS SAMPLING

A

● Performed during 10-12th week of pregnancy.
● Provides earlier results than amniocentesis.
● Does not detect metabolic problems.
● Has greater risk of spontaneous abortion.

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18
Q

____________ correspond to _____ copies of ___________.

A

Fluorescent dots
three
chromosome 21

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19
Q

● Schematic chromosome map.
● Indicates chromosome arms (p or q)and major regions delineated by banding patterns

A

IDEOGRAM

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20
Q

Karyotype may be abnormal in:

A

○ Chromosome number
○ Chromosome structure

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21
Q

Abnormal chromosomes account for at least ____ of ____________.

A

50%
spontaneous abortions.

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22
Q

People are being diagnosed with chromosomal abnormalities due to _______________.

A

improved technology

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23
Q

Extra chromosome sets

A

Polyploidy

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24
Q

An extra or missing chromosome

A

Aneuploidy

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25
One chromosome absent
Monosomy
26
One chromosome extra
Trisomy
27
___________ and __________ proved direct detection of _____________.
Amniocentesis and chorionic villus sampling extra chromosomes
28
____________ offer an indirect method
Maternal serum markers
29
Cell-free DNA Testing can ve performed at least __ weeks into pregnancy
10 weeks
30
In cell-free DNA Testing up to 20 percent of these pieces come from the ________, and thus represent the ____________.
placenta fetal genome
31
______ cells have three sets of chromosomes. Produced by:
Triploid ■ Fertilization of one egg by two sperm ■ Fusion of haploid and diploid cells
32
Those born with aneuploidy are more likely to have____________ rather than _______.
an extra chromosome (trisomy) a missing one (monosomy)
33
Aneuploidy arises during _______, producing groups of _________ with the extra or missing chromosomes.
mitosis somatic cells
34
Individual with two chromosomally-distinct cell populations is called a _________.
mosaic
35
_________ cease developing as embryos or fetuses.
Autosomal aneuploids
36
Frequently seen _________ in newborns are those of chromosomes ___,____, and ___.○ Carry fewer genes than other autosomes.
trisomies 21, 18, and 13
37
● Most common trisomy among newborns. ● Distinctive facial and physica lproblems.
DOWN SYNDROME
38
TRISOMY __ ● Due to nondisjunction in meiosis II cccc in oocyte and generally do not survive .● Serious mental and physical disabilities. ● Distinctive feature - Oddly clenched fists.
TRISOMY 21 EDWARDS SYNDROME
39
TRISOMY ___ ● Very rare and generally do not survive 6 months. ● Serious mental and physical disabilities. ● Distinctive feature - eye fusion.
TRISOMY 13 PATAU SYNDROME
40
TRISOMY __ ● One in 2500 female births. ● 99% of affected fetuses die in utero. ● Features: ○ Short stature ○ Webbing at back of neck ○ Incomplete sexual development (infertile) ○ Impaired hearing ● Individuals who are mosaics may have children.
TRISOMY 13 TURNER (XO) SYNDROME
41
TRISOMY __ ● One in 1000 female births. ● Few modest effects on phenotype include tallness, menstrual irregularities, and a slight impact on intelligence. ● X inactivation of two X chromosomes occurs and cells have two Barrbodies. ● May compensate for the presence of extra X.
TRISOMY 13 TRIPLO-X SYNDROME
42
TRISOMY __ ● One in 500 male births. ● Phenotypes include: ○ Incomplete sexual development ○ Rudimentary testes and prostate ○ Long limbs, large hands, and feet ○ Some breast tissue development ● Common cause of male infertility
TRISOMY 13 KLINEFELTER (XXY) SYNDROME
43
TRISOMY __ ● Arises due to unusual oocyte and sperm. ● Associated with more severe behavioral problems than Klinefelter syndrome. ○ AAD, obsessive-compulsive disorder, learning disabilities ● Individuals are infertile. ● Treated with testosterone
TRISOMY 13 XXYY SYNDROME
44
TRISOMY __ ● One in 1000 male births ● 96% are phenotypically normal ● Modest phenotypes ○ Great height ○ Acne ○ Speech and reading disabilities. ● Studies suggest increase in aggressive behaviors are not supported.
TRISOMY 13 JACOBS (XYY) SYNDROME
45
Missing genetic segment from a chromosome.
DELETION
46
Deletion is often not inherited, rather they arise
de novo
47
Larger deletions increase the likelihood that there will be an ______
associated phenotype
48
Deletion 5p
Cri-du-chat (cat cry) syndrome.
49
● Presence of an extra genetic segment on a chromosome. ○ Often not inherited. ○ Rather they arise ____.
DUPLICATION de novo
50
Duplication's effect on the phenotype is generally dependent on their
size
51
Two nonhomologous chromosomes exchange segments.
TRANSLOCATIONS
52
Translocations types :
○ Robertsonian Translocation ○ Reciprocal Translocation
53
Two nonhomologous acrocentric chromosomes break at the centromere and their long arms fuse.
ROBERTSONIAN TRANSLOCATIONS
54
Translocation carriers have __ chromosomes. Produce _________ gametes.
45 unbalanced
55
__ of Down syndrome results from a ________________ between chromosomes ___ and _____.
5% Robertsonian translocation 21 and 14.
56
Tends to recur in families, who also have more risk of spontaneous abortions.
TRANSLOCATION DOWN SYNDROME
57
Two nonhomologous chromosomes exchange parts
RECIPROCAL TRANSLOCATIONS
58
_________ : Chromosome segment that is flipped in orientation. ______ cause health problems probably due to ______ at the _______. May impact ___________.
INVERSIONS 5-10% disruption of genes breakpoints meiotic segregation
59
Inverted region does not include centromere.
Paracentric inversion
60
Inverted region includes centromere
Pericentric inversion
61
● Chromosomes with identical arms. ● Formed when centromeres divide along the incorrect plane during meiosis.
ISOCHROMOSOMES
62
● Occur in 1 of 25,000 conceptions. ● Arise when telomeres are lost and sticky chromosome ends fuse. ● Genes can be lost or disrupted causing symptoms.
RING CHROMOSOMES
63
TRAITS INHERITED ON SEX CHROMOSOMES Passed from fathers to sons only.
Y-Linked Traits
64
TRAITS INHERITED ON SEX CHROMOSOMES ○ Passed from mother to son because he inherits his X from his mother and his Y from his father. ○ May be dominant or recessive. ○ X-linked dominant traits are more devastating to males.
X-Linked Traits
65
Shuts off one X chromosome in each cell in female mammals making them mosaics for heterozygous X-linked genes.
X INACTIVATION
66
In humans, it can be used to identify carriers of some X-linked diseases such as _______ in which an affected boy has ___________.
Lesch-Nyhan syndrome cerebral palsy

Cytogenetics (4 decks)

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