Chromosomal Aberrations

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Questions and Answers

Which condition is characterized by having an extra chromosome 18?

  • Trisomy 8
  • Trisomy 18 (correct)
  • Trisomy 13
  • Trisomy 21

What is the most common result of Monoploidy in animals?

  • Normal development
  • Enhanced survival rates
  • Increased muscle tone
  • Lethality (correct)

Which of the following syndromes is associated with an additional two X chromosomes?

  • XXYY syndrome
  • Penta X Syndrome
  • Klinefelter's syndrome (correct)
  • Turner syndrome

Which type of chromosomal aberration involves a complete loss of homologous chromosome pairs?

<p>Nullisomy (B)</p> Signup and view all the answers

What is the term used to refer to the full set of chromosomes from an individual?

<p>Karyotype (B)</p> Signup and view all the answers

What type of chromosomal abnormality is Euploidy?

<p>Presence of additional complete sets of chromosomes (C)</p> Signup and view all the answers

Which type of chromosomal abnormality occurs when a whole chromosome is missing?

<p>Monosomy (B)</p> Signup and view all the answers

Which type of chromosomal aberration includes deletions, duplications, and inversions?

<p>Structural aberrations (A)</p> Signup and view all the answers

Which condition results in individuals having five X chromosomes?

<p>Penta X Syndrome (C)</p> Signup and view all the answers

What is the main consequence of numerical chromosomal aberrations such as aneuploidy?

<p>The gain or loss of one or more chromosomes (A)</p> Signup and view all the answers

What does the term 'Polyploidy' refer to?

<p>Having three or more sets of chromosomes (A)</p> Signup and view all the answers

Which syndrome is an example of trisomy?

<p>Down syndrome (A)</p> Signup and view all the answers

How are chromosomal aberrations typically confirmed?

<p>Karyotype comparison (B)</p> Signup and view all the answers

What is the primary cause of chromosomal abnormalities?

<p>Error in cell division (D)</p> Signup and view all the answers

What effect do structural aberrations generally have on chromosomes?

<p>Alter the arrangement of genetic material (C)</p> Signup and view all the answers

What typically allows balanced chromosomal rearrangements to go unnoticed?

<p>They do not affect the amount of DNA present. (D)</p> Signup and view all the answers

A person with Turner syndrome typically has how many chromosomes?

<p>45 chromosomes (B)</p> Signup and view all the answers

Which syndrome is associated with a deletion of a portion of chromosome 4?

<p>Wolf-Hirschhorn syndrome (C)</p> Signup and view all the answers

What is the result of a duplication in genetic material?

<p>Additional genetic material is present. (A)</p> Signup and view all the answers

Which of the following types of structural aberrations involves the transfer of a chromosome segment to another chromosome?

<p>Translocation (B)</p> Signup and view all the answers

What characterizes a Robertsonian translocation?

<p>One complete chromosome joins another at the centromere. (C)</p> Signup and view all the answers

Which factor is NOT associated with the occurrence of chromosomal aberrations?

<p>Genetic inheritance from both parents (C)</p> Signup and view all the answers

What type of chromosomal aberration involves a chromosome breaking, turning upside down, and reattaching?

<p>Inversion (A)</p> Signup and view all the answers

What is mosaicism in the context of chromosomal abnormalities?

<p>Presence of the abnormality in some but not all cells. (C)</p> Signup and view all the answers

Flashcards

Chromosomal Aberration

A defect in the number or arrangement of chromosomes in a cell.

Numerical Aberration

A change in the number of chromosomes, often due to errors in cell division.

Aneuploidy

A change in the number of chromosomes, where a single chromosome is either gained or lost.

Monosomy

A type of aneuploidy where an organism loses a chromosome.

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Trisomy

A type of aneuploidy where an organism gains an extra chromosome.

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Down Syndrome

A genetic disorder caused by trisomy of chromosome 21, resulting in 47 chromosomes.

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Turner Syndrome

A genetic disorder resulting from monosomy of the X chromosome (45 chromosomes).

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Karyotype

A visual representation of an organism's complete set of chromosomes.

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Chromosome 18 Trisomy

A genetic condition with an extra copy of chromosome 18.

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Chromosome 13 Trisomy

A genetic condition with an extra copy of chromosome 13.

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Monoploidy

Having only one set of chromosomes (1n).

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Polyploidy

Having three or more sets of chromosomes.

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Structural Aberrations

Changes in the structure of chromosomes (e.g., deletions, duplications).

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Nondisjunction

Chromosomes fail to separate properly during cell division.

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Balanced chromosomal rearrangements

Chromosomal rearrangements that do not cause disease because the full complement of DNA material is present.

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Deletions

A part of a chromosome is missing or removed, leading to genetic disorders.

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Duplications

A part of a chromosome is duplicated, resulting in extra genetic material.

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Translocations

Part of a chromosome is transferred to another chromosome.

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Reciprocal translocation

Segments of two different chromosomes are exchanged.

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Robertsonian translocation

One entire chromosome joins another at the centromere.

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Chromosomal abnormalities cause

Occur by accident during egg or sperm formation, or early fetal development, or due to maternal age or environmental factors.

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Mosaicism

Some cells have the abnormality, others don't.

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Study Notes

Chromosomal Aberrations

  • Chromosomal aberrations occur due to defects in chromosome number or arrangement of genetic material (genes) within a chromosome.
  • These abnormalities lead to specific physical symptoms, though severity varies depending on the type of aberration.
  • Aberrations can involve extra genetic material attached to a chromosome, missing whole chromosomes, or faulty chromosome formations.
  • Increases (duplications) or decreases (deletions) in chromosomal material disrupt normal development and function.
  • Normal human cells contain 46 chromosomes. Any changes in this number or structure cause anomalies.
  • Karyotype analysis compares a genome to the "normal" karyotype of a species to identify abnormalities.
  • Errors during cell division (meiosis or mitosis) commonly lead to chromosomal abnormalities.

Types of Chromosomal Anomalies

Numerical Aberrations

  • These are caused by errors during chromosome division in meiosis, resulting in extra or missing chromosomes.
  • Common types include:
    • Aneuploidy: Gain or loss of one or more, but not a complete set, of chromosomes, affecting the nuclei.
      • Examples: Down Syndrome (47 chromosomes), Turner Syndrome (45 chromosomes).
    • Polyploidy: Gain of a whole set of chromosomes (3n, 4n, etc.)
      • Examples: Triploidy (3n), Tetraploidy (4n).
    • Monoploidy (n): Single set of chromosomes, often lethal in animals but tolerated in some plants.

Structural Aberrations

  • These result from changes in the chromosome's structure, not the number.
  • Types include:
    • Deletions: Loss of a chromosome segment.
    • Duplications: Duplication of a chromosome segment.
    • Inversions: A chromosome segment reverses.
    • Translocations: Transfer of a chromosome segment to another chromosome.
    • Insertions: Insertion of a segment from one chromosome into another.
    • Rings: Formation of a circular chromosome due to breaks and re-joining.
    • Isochromosomes: A chromosome with duplicated copies of one arm and a missing other.

How Chromosomal Aberrations Occur

  • Errors during egg or sperm development, or early fetal development, are common causes.
  • Maternal age and some environmental factors can contribute to the risk of chromosomal anomalies.
  • Most abnormalities are not inherited, arising as random events in the reproductive cells.
  • In mosaicism, there are cells with and without the abnormality.
  • Prenatal testing can detect some, but not all, chromosomal abnormalities.

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