Changes in Chromosome Number

This set of flashcards covers vocabulary and key concepts related to changes in chromosome number, including aneuploidy and polyploidy, derived from genetics lectures.

Chromosome Number

The total number of chromosomes in a cell, which is crucial for proper cell function, replication, and organism viability.

Aneuploidy

The presence of an abnormal number of chromosomes in a cell, which can result from the addition or loss of chromosomes from homologous pairs.

Polyploidy

The condition in which a cell has more than two complete sets of chromosomes, common in many plant species.

Diploidy

The condition of having two homologous sets of chromosomes, represented as 2n.

Tetraploid

An organism that has four sets of chromosomes, represented as 4n.

Stability in Polyploids

Stable polyploids usually have an even number of chromosome sets, which allows for proper meiosis and fertility.

Triploid

An organism that has three sets of chromosomes, often resulting in sterility due to improper chromosome pairing during meiosis.

Monosomy

The loss of one chromosome from a pair, leading to an organism having only one copy of that chromosome (2n-1).

Trisomy

The presence of an extra chromosome, resulting in three copies instead of two (2n+1), with Trisomy-21 being a well-known example (Down syndrome).

Gene Dosage

The number of copies of a gene present in a cell or organism, which can affect the phenotype and viability of the organism depending on its balance.

Down Syndrome

A genetic disorder caused by trisomy of chromosome 21, leading to developmental and health issues.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during cell division, resulting in aneuploidy.

Haploid

A cell that has only one complete set of chromosomes, represented as n.

Euploid

A cell with a normal and balanced number of chromosomes that is functioning effectively.

Klinefelter Syndrome

A genetic condition in males characterized by the presence of an extra X chromosome, resulting in the karyotype 47,XXY.