47. Chromosomal (structural) mutations - definition, different rearrangements, “chromosomal diseases”. Flashcards

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1
Q

Translation - refers to an exchange of chromosome segments. With centric fusion, 2 complete chromosomes are involved
Reciprocal translation - only a part of the 2 chromosomes is exchanged

A

Translation - refers to an exchange of chromosome segments. With centric fusion, 2 complete chromosomes are involved
Reciprocal translation - only a part of the 2 chromosomes is exchanged

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2
Q

Genetic fusion of afrocentric chromosomes:

  • chromosome 14 and chromosome 21 pair during meiosis, different gametes are formed after fertilisation, the corresponding zygotes contain:
  • either only 1 chromosome 21 (unviable monosomy 21)
  • a normal chromosome complement
  • on balanced chromosome complement with the fused chromosome
  • 3 chromosome 21 (trisomy 21) - leads to down syndrome
A

Genetic fusion of afrocentric chromosomes:

  • chromosome 14 and chromosome 21 pair during meiosis, different gametes are formed after fertilisation, the corresponding zygotes contain:
  • either only 1 chromosome 21 (unviable monosomy 21)
  • a normal chromosome complement
  • on balanced chromosome complement with the fused chromosome
  • 3 chromosome 21 (trisomy 21) - leads to down syndrome
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3
Q

Reciprocal translocation:

  • chromosome material is either lost or gained as a result it doesn’t cause clinical signs (it’s balanced)
  • carriers may form gametes with unbalanced chromosome complements
A

Reciprocal translocation:

  • chromosome material is either lost or gained as a result it doesn’t cause clinical signs (it’s balanced)
  • carriers may form gametes with unbalanced chromosome complements
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4
Q

Balanced and unbalanced effects:

  • balanced rearrangement - no chromosomal material has been lost or gained - no effect on phenotype
  • unbalanced abberations - chromosomal material has either been added (partial duplication or lost, partial deficiency)
A

Balanced and unbalanced effects:

  • balanced rearrangement - no chromosomal material has been lost or gained - no effect on phenotype
  • unbalanced abberations - chromosomal material has either been added (partial duplication or lost, partial deficiency)
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5
Q

Isochromosomes - arises when a normal chromosome divides transversely instead of longitudinally so that it is composed of 2 long or 2 short arms

Dicentric chromosomes:

  • contain 2 centromeres
  • unstable - torn apart during mitosis - parts are divided between two daughter cells
A

Isochromosomes - arises when a normal chromosome divides transversely instead of longitudinally so that it is composed of 2 long or 2 short arms

Dicentric chromosomes:

  • contain 2 centromeres
  • unstable - torn apart during mitosis - parts are divided between two daughter cells
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6
Q

Ring chromosomes

  • arise after 2 breaks followed by joining of 2 cap ends
  • distal segments are lost
  • .’. a ring chromosome is unbalanced
A

Ring chromosomes

  • arise after 2 breaks followed by joining of 2 cap ends
  • distal segments are lost
  • .’. a ring chromosome is unbalanced
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7
Q

Inversion - an inversion is a 180* change in direction of a chromosomal segment

Interchromosomal and intrachromasomal mutations - translocations

Intra - deletion - structural chromosomal diseases resulting from deletions = Prader-Willi’s

A

Inversion - an inversion is a 180* change in direction of a chromosomal segment

Interchromosomal and intrachromasomal mutations - translocations

Intra - deletion - structural chromosomal diseases resulting from deletions = Prader-Willi’s

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