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Molecular biology > 5-Chromosomal_Abnormalities_Flashcards > Flashcards

5-Chromosomal_Abnormalities_Flashcards

1
Q

How many chromosomes do humans typically have?

A

46 chromosomes (23 pairs).

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2
Q

What are the two types of chromosomes in humans?

A

Autosomes (22 pairs) and sex chromosomes (1 pair: XX or XY).

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3
Q

What are chromosomal abnormalities?

A

Errors in the number or structure of chromosomes leading to health problems.

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4
Q

What are some effects of chromosomal abnormalities?

A

Miscarriages, stillbirths, malformations, intellectual disabilities, and identifiable syndromes.

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5
Q

What are the two main categories of chromosomal abnormalities?

A

Numerical and structural disorders.

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6
Q

What is aneuploidy?

A

A deviation from the normal diploid number of chromosomes.

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7
Q

Give an example of aneuploidy.

A

Trisomy (2n+1) or monosomy (2n-1).

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8
Q

What is polyploidy?

A

A change involving multiples of the haploid set of chromosomes (e.g., triploidy, tetraploidy).

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9
Q

What is a deletion?

A

Loss of a chromosome segment.

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10
Q

What is a translocation?

A

Exchange of segments between chromosomes.

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11
Q

What is an inversion?

A

Reversal of a chromosome segment.

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12
Q

What is a ring chromosome?

A

A chromosome forms a circular structure due to end fusion.

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13
Q

What are the two types of cell division where errors can occur?

A

Mitosis and meiosis.

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14
Q

What is nondisjunction?

A

Failure of chromosomes to separate properly during cell division.

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15
Q

What is mosaicism?

A

Presence of two or more cell populations with different genotypes from one zygote.

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16
Q

What causes Down syndrome (Trisomy 21)?

A

An extra copy of chromosome 21.

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17
Q

What are some characteristics of Down syndrome?

A

Intellectual disability, distinct facial features, and heart defects.

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18
Q

What causes Patau syndrome (Trisomy 13)?

A

An extra copy of chromosome 13.

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19
Q

What is the prognosis for Patau syndrome?

A

Most affected individuals die within the first year of life.

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20
Q

What causes Edwards syndrome (Trisomy 18)?

A

An extra copy of chromosome 18.

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21
Q

What is the prognosis for Edwards syndrome?

A

Most affected individuals die within the first year of life.

22
Q

What causes Turner syndrome (XO)?

A

Missing one X chromosome in females (45, XO).

23
Q

What are some features of Turner syndrome?

A

Short stature, webbed neck, and infertility.

24
Q

What causes Klinefelter syndrome (XXY)?

A

An extra X chromosome in males (47, XXY).

25
Q

What are characteristics of Klinefelter syndrome?

A

Infertility, reduced body hair, and learning difficulties.

26
Q

What is Triple X syndrome (XXX)?

A

Females with an extra X chromosome (47, XXX).

27
Q

What is Double Y syndrome (XYY)?

A

Males with an extra Y chromosome (47, XYY).

28
Q

What is Cri-du-chat syndrome?

A

Deletion on the short arm of chromosome 5.

29
Q

What causes DiGeorge syndrome?

A

Microdeletion on chromosome 22q11.2.

30
Q

What is Angelman syndrome?

A

Deletion on chromosome 15 inherited from the mother.

31
Q

What is Prader-Willi syndrome?

A

Deletion on chromosome 15 inherited from the father.

32
Q

What is a Robertsonian translocation?

A

Fusion of long arms of two acrocentric chromosomes.

33
Q

What is cytogenetics?

A

Study of chromosomes, their structure, and inheritance.

34
Q

What is karyotyping?

A

Visual representation of chromosomes arranged in pairs.

35
Q

What does G-banding in karyotyping do?

A

Produces characteristic banding patterns for chromosome identification.

36
Q

What is FISH (Fluorescence In Situ Hybridization)?

A

A technique to detect specific DNA sequences using fluorescent probes.

37
Q

What is spectral karyotyping (SKY)?

A

Assigns a different color to each chromosome for visualization.

38
Q

What is array-CGH?

A

High-resolution technique to detect DNA gains or losses.

39
Q

How is a normal female karyotype written?

A

46, XX.

40
Q

How is Down syndrome written in karyotype notation?

A

47, XY, +21.

41
Q

What does ‘del’ indicate in karyotype nomenclature?

A

Deletion.

42
Q

What does ‘t’ indicate in karyotype nomenclature?

A

Translocation.

43
Q

What disorders can cytogenetic testing diagnose?

A

Down syndrome, Turner syndrome, and Cri-du-chat syndrome.

44
Q

What is the role of cytogenetics in genetic counseling?

A

Provides families with information on chromosomal abnormality risks.

45
Q

How is prenatal screening performed?

A

Through amniocentesis or chorionic villus sampling.

46
Q

What are euchromatin and heterochromatin?

A

Euchromatin is transcriptionally active; heterochromatin is condensed and inactive.

47
Q

What are Barr bodies?

A

Inactivated X chromosomes in females.

48
Q

What does XCI stand for?

A

X-chromosome inactivation.

49
Q

What is the typical size of the human genome?

A

3.2 billion base pairs.

50
Q

What is the ISCN?

A

International System for Human Cytogenetic Nomenclature.

Molecular biology (10 decks)

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