Chromosome Mutations Flashcards

Flashcards about chromosome mutations, aneuploidy, and polyploidy.

What is a chromosome rearrangement?

A change in the structure of chromosomes.

What is aneuploidy?

A change in the number of chromosomes.

What is polyploidy?

One or more complete sets of chromosomes are added.

What are the three main types of chromosome mutations?

Rearrangements, Aneuploidy, and Polyploidy

What is a chromosome duplication?

A segment of the chromosome is duplicated.

What is a chromosome deletion?

A segment of the chromosome is deleted.

What is a chromosome inversion?

A segment of the chromosome is turned 180°.

What is a chromosome translocation?

A segment of a chromosome moves from one chromosome to a nonhomologous chromosome or to another place on the same chromosome.

What happens during meiosis when a chromosome has a duplicated region?

The duplicated region must loop out to allow the homologous sequences of the chromosomes to align.

What is unbalanced gene dosage due to duplication?

Duplications and other chromosome mutations produce extra copies of some, but not all, genes which alters the relative amounts (doses) of interacting products.

How can a deletion or duplication arise?

Unequal crossover

What is a potential consequence of a chromosome break?

Broken gene, Gene separated from regulatory sequence, Gene with new regulatory sequence, Chromatin change, Fusion genes

What are some symptoms of Cri-du-chat syndrome, associated with a deletion on chromosome 5?

Small head, distinctive cry, widely spaced eyes, round face, intellectual disability

What are the effects of deletions?

Imbalances in gene product, expression of a normally recessive gene (pseudodominance), haploinsufficiency

What happens during pairing of homologs in Prophase I with a deletion?

The normal chromosome loops out.

What are the two types of inversions?

Paracentric and Pericentric

What happens in individuals heterozygous for inversions during meiosis?

Homologous sequences align only if the two chromosomes form an inversion loop.

What is a paracentric inversion?

Inversion that does not include the centromere in the inverted region

What is a pericentric inversion?

Inversion that includes the centromere in the inverted region

What happens to gametes formed in a paracentric inversion?

They demonstrate reduced recombination in a paracentric inversion, as gametes formed result in nonviable offspring.

What happens to gametes formed in a pericentric inversion?

Have abnormal gametes formed in a pericentric inversion

When does an inversion loop form?

Prophase I

What is a key event that occurs during Anaphase I involving an inversion?

The centromeres separate, stretching the dicentric chromatid, which breaks. The chromosome lacking a centromere is lost

What are the three types of translocations?

Nonreciprocal translocation, Reciprocal translocation, Robertsonian translocation

What happens during Robertsonian translocation?

The short arm of one acrocentric chromosome is exchanged with the long arm of another, creating a large metacentric chromosome, and a fragment that often fails to segregate and is lost.

What configuration forms in prophase I of meiosis in a reciprocal translocation?

Crosslike configuration

What are fragile sites?

Chromosomal regions susceptible to breakage

What are the causes of aneuploidy?

Deletion of centromere during mitosis and meiosis, Robertsonian translocation, Nondisjunction during meiosis and mitosis

How can aneuploids be produced?

Through nondisjunction

Name the types of aneuploidy?

Nullisomy, Monosomy, Trisomy, Tetrasomy

How many chromosomes will be found in a trisomic member of a species with 2n = 36 chromosomes?

37

Name a few examples of autosomal aneuploids.

Down syndrome, Edwards syndrome, Patau syndrome

Name a few examples of sex-chromosome aneuploids.

Turner syndrome; XO, Klinefelter syndrome; XXY

What are the effects of polyploidy?

Increase in cell size, larger plant attributes, Evolution: may give rise to new species.

What are the main types of polyploidy?

Autopolyploidy and Allopolyploidy