Chromosomes (10) Flashcards

1
Q

Which is not an acrocentric chromosome?

a. 15
b. 12
c. 21
d. 13

A

b. 12

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2
Q

What is FALSE about Robertsonian Translocation?

a. It occurs between two acrocentric chromosomes
b. The most common is t(13;14)
c. It can cause Chronic Myelogenous Leukaemia
d. The relevant chromosomes contain nucleolar organiser centres (rRNA) in their short arms

A

c. It can cause Chronic Myelogenous Leukaemia

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3
Q

Which statement about translocations and cancer is correct?

a. CML results from increased tyrosine kinase activity following a translocation of chromosomes 9 and 22 and the formation of a bcr-c-abl fusion protein
b. CML occurs when the Myelogenous gene on chromosome 8 fuses near the Leukaemia gene enhancer on chromosome 14
c. Burkitts lymphoma results from increased tyrosine kinase activity following a translocation of chromosomes 14 and 8 and the formation of a IgG-c-myc fusion protein
d. Burkitts lymphoma occurs when the Ig heavy chain enhancer on chromosome 14 translocates near the c-abl proto-oncogene on chromosome 9

A

a. CML results from increased tyrosine kinase activity following a translocation of chromosomes 9 and 22 and the formation of a bcr-c-abl fusion protein

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4
Q

What is correct about isochromsomes?

a. They occur most often from Y chromosomes
b. They occur when a chromosome splits horizontally to produce a 2 p armed product and 2 q armed product
c. They cannot be observed in X chromsomes
d. They will not alter the phenotype of an individual

A

b. They occur when a chromosome splits horizontally to produce a 2 p armed product and 2 q armed product

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5
Q

Which statement is correct?

a. Euploidy refers to the addition or loss of chromosomes, for example trisomy 21
b. Aneuploidy refers to having more than a diploid set of chromosomes
c. Abnormal diploids have two sets of chromosomes only from one parent
d. Euploidy is commonly observed in humans with Turners syndrome and elephantitis

A

c. Abnormal diploids have two sets of chromosomes only from one parent

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6
Q

• Reciprocal translocation involves the fusion of two acrocentric chromosomes whilst Robertsonian translocation involves the exchange of genetic material between chromosomes.

A

F

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7
Q

• Following reciprocal translocation, only alternate segregation can lead to balanced gametes.

A

T

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8
Q

• Reciprocal translocations are the cause of heritable trisomy 21.

A

F (Robertsonian)

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9
Q

What is not involved in preparing a karyotype?

a. Centrifugation if using blood in order to separate RBC from WBC
b. Colchicine to bind tubulin and prevent spindle formation
c. Staining with heparin if blood
d. Tissue culture with phytohaemogluttin to promote mitosis

A

c. Staining with heparin if blood

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10
Q

What is false about banding techniques?

a. NOR banding is the reverse to G banding
b. Q banding requires a fluorescent dye
c. T banding is specialised R banding for telomeres
d. C banding can pick up centromeres and heterochromatin

A

a. NOR banding is the reverse to G banding

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11
Q

What does 1q21 refer to?

a. The band is in region 1 on the q arm of chromosome 2
b. The band of interest is on chromosome 21
c. There is only one copy of chromosome 2
d. The band is in region 2 on the q arm of chromosome 1

A

d. The band is in region 2 on the q arm of chromosome 1

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12
Q

What is not an example of a common polymorphism observed in normal karyotypes?

a. Heterochromatin levels can vary greatly around chromosome 9
b. Satellite size in chromosomes 13, 14, 15, 21 and 22
c. Spontaneous fragile sites that cannot be passed on to offspring
d. The length of the Y chromosome q arm

A

c. Spontaneous fragile sites that cannot be passed on to offspring

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13
Q

What is false about fragile X syndrome?

a. The site is at Xq27
b. There is a triplet repeat (CGG) in the 5’ UTR of FMR1 which results in promoter methylation
c. Females have stronger phenotypes (mental retardation) than males
d. >200 repeats of CGG are required for an individual to be affected with fragile X

A

c. Females have stronger phenotypes (mental retardation) than males

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14
Q

Which describes a female with a terminal deletion in region 2, band 5 on the q arm chromosome 3?

a. 46, XX, del (3) q25
b. Del, 46, XX, (3) q25
c. XX, del, (3), qq, 2, 5
d. 46, XX, del, 2q5, (3)

A

a. 46, XX, del (3) q25

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15
Q

What does 46, XY, del (6)(q13q22) refer to?

a. A male has a terminal deletion at q13 and q22
b. There is a interstitial deletion on the q arm of chromosome 6
c. There is an interstitial deletion that has resulted in losing all parts of the chromosome except for the section between region 1, band 3 and region 2, band 2 on the q arm
d. The section between region 1, band 3 and region 2, band 2 on the q arm of chromosome 6 has been replaced

A

b. There is a interstitial deletion on the q arm of chromosome 6

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16
Q

What does 46, XY, dup(6) (q21 → q22) refer to?

a. Chromosome 6 has been duplicated and lost region 2 on the q arm
b. This male has twice as many copies of chromosome 6 compared to a healthy individual
c. There has been a duplication of the section between q arm, region 2, band 1 and q arm region 2, band 2 on chromosome 6
d. Region 2, band 2 has been replaced with region 2, band 1 on the q arm of chromosome 6

A

c. There has been a duplication of the section between q arm, region 2, band 1 and q arm region 2, band 2 on chromosome 6

17
Q

What is false about the following chromosome abnormality: 46, XY, ins (3;4) (q13;q13q26)

a. Chromosome 3 is the receiving the insertion and is broken at q13
b. The insertion is the segment between region 1, band 3 and region 2, band 6 on the q arm of chromosome 4
c. Chromosome 3 is donating the segment between region 1, band 3 and region 2, band 6 on the q arm
d. Chromosome 3 and chromosome 4 are exchanging genetic material between homologous regions of their q arms

A

c. Chromosome 3 is donating the segment between region 1, band 3 and region 2, band 6 on the q arm

18
Q

What are the products of a pericentric inversion event?

a. 2 non-recombinant chromosomes, a dicentric chromosome and an acentric chromosome
b. 3 deletion products and 1 viable chromosome
c. 2 non-recombinant chromosomes and 2 imbalanced chromosomes
d. An inversion product, normal product and 2 deletion products

A

c. 2 non-recombinant chromosomes and 2 imbalanced chromosomes

19
Q

What does 46, XY, inv ins (3;4) (q13;q26q13) mean?

a. Region 2, band 6 is closer to the chromosome 3 centromere than region 1, band 3 on the q arm because of inversion and insertion
b. Region 2, band 6 is closer to the chromosome 4 centromere than region 1, band 3 on the q arm
c. Chromosome 3 has donated the section of the q arm between region 2, band 6 and region 1, band 3 to chromosome 4
d. This individual has Cru du Chat syndrome

A

a. Region 2, band 6 is closer to the chromosome 3 centromere than region 1, band 3 on the q arm because of inversion and insertion

20
Q

What causes complete androgen insensitivity?

a. Deletion of the Xq11.2-12 region where the androgen receptor gene is housed
b. Duplication of the Xq11.2-12 region on both X chromosomes
c. An inversion with a break point in the Xq11.2-12 region
d. 46, XY, inv ins (3;4) (q13;q26q13)

A

c. An inversion with a break point in the Xq11.2-12 region

21
Q

• To study chromosomes, you must use dividing cells.

A

T

22
Q

• FISH can label whole chromosomes but not single segments.

A

F

23
Q

• Karyograms show a set of banded chromosomes and Karyotypes show the chromosome complement of an individual.

A

T

24
Q

• Most karyograms relate to Q banding.

A

F

25
Q

• The long arm of the chromosome is called the P arm.

A

F

26
Q

• Chromosomes are divided into regions and numbered out from the centromere.

A

T

27
Q

• A satellite site is a non-staining gap in a chromosome that is inherited according to Mendelian inheritance.

A

F (fragile)

28
Q

• Paracentric inversions include the centromere.

A

F

29
Q

• Inversions are caused by recombination events within the inversion loop.

A

T