Chromosome Variations and Mutations in Human and Plant Genetics

What is aneuploidy?

A change in the number of individual chromosomes.

What is polyploidy?

A condition where there is a full set of extra chromosomes.

What is trisomy-21 also known as?

Down's Syndrome.

What is nullisomy?

The loss of both members of a homologous pair (2n - 2).

What is monosomy?

The loss of one member of a homologous pair (2n - 1).

What is the only viable monosomy in humans?

Turner's syndrome (XO).

What is tetrasomy?

The gain of a pair of homologous chromosomes (2n + 2).

What is the most frequent mechanism for Trisomy-21?

Spontaneous maternal nondisjunction in Meiosis I.

What are the common phenotypes associated with Turner's syndrome?

Height issues, wide chest, reproduction issues, and narrowing of the aorta.

What is the typical karyotype for Down's Syndrome?

(47, XX, +21) or (47, XY, +21).

What happens during nondisjunction in Meiosis I?

Homologous chromosomes fail to separate, leading to gametes with abnormal chromosome numbers.

What is the outcome of nondisjunction in Meiosis II?

Sister chromatids fail to separate, resulting in some normal gametes and some with abnormal chromosome numbers.

What is the significance of Barr bodies in relation to trisomy?

Extra X chromosomes in conditions like Triplo-X and Klinefelter's syndrome are inactivated as Barr bodies.

What is the difference between autopolyploidy and allopolyploidy?

Autopolyploidy involves extra chromosome sets from the same species, while allopolyploidy involves hybridization between two different species.

What is a common example of polyploidy in plants?

Bread wheat (Triticum aestivum) formed through hybridization events.

What types of organisms can exhibit polyploidy?

Some fish and amphibian species, as well as certain human cells like liver and heart cells.

What is the expected chromosome number in allotriploidy involving two species with 2n = 8 and 2n = 14?

Expected chromosome number would be 3n = 8 + 14 = 22.

What is the expected chromosome number in autotetraploidy in species II with 2n = 14?

Expected chromosome number would be 4n = 28.

What is the expected chromosome number in trisomy in species I with 2n = 8?

Expected chromosome number would be 2n + 1 = 9.

What is the expected chromosome number in monosomy in species II with 2n = 14?

Expected chromosome number would be 2n - 1 = 13.