• Review: The addition or deletion of an entire chromosome can lead to a serious genetic condition. • An alteration in the structure of a chromosome can lead to genetic disorders. • The possible alterations are deletion and crossover mistakes. • Two types of crossover mistakes include duplications and inversions. - Review: During meiosis, homologous chromosomes can exchange parts. The process takes place during crossing over (when segments break off and recombine.) - Mistakes sometimes occur during this process. Parts of the chromosome may break off, and genetic information will be lost. - In a deletion mutation, a portion of the chromosome is lost entirely. The disease Cri du chat is caused by a deletion of chromosome #5. The name literally translates as “cry of the cat” because of the cat-like cry of children with the disorder. Individuals with this disease are microcephalic, mentally retarded, and have a shortened lifespan. - In a duplication mutation, a portion of the chromosome is present in extra copies. Duplications can occur from an unequal crossover event, causing one of the chromosomes to get a portion of the other one. A duplication can result in extra copies of the gene being made. - In an inversion mutation, part of the chromosome flips around, possibly reversing the order of the gene sequence

Two types of crossover mistakes that lead to a change in the structure of a chromosome are:

- Duplication mutations and inversion mutations

What occurs in an inversion mutation?

- A section of a chromosome is flipped around.

Which statement concerning homologous chromosomes is not true?

- It is not common for homologous chromosomes to trade genes.

Which of the following are two ways that chromosome structures can be altered?

- Deletion mistakes and crossover mistakes

9.10.2 Problems in Heredity: Chromosomal Aberrations Flashcards by Irina Soloshenko

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9.10.2 Problems in Heredity: Chromosomal Aberrations Flashcards

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