large scale chap 17

Haploid organism

An organism with a single complete set of chromosomes (n), typically found in gametes.

Diploid organism

An organism with two complete sets of chromosomes (2n), one from each parent.

Monoploid

An organism from a normally diploid species that possesses only one set of chromosomes (n).

Polyploid

An organism with more than two sets of chromosomes.

Autopolyploids

Organisms with multiple sets of chromosomes from the same species.

Allopolyploids

Organisms with chromosome sets from two or more species.

Triploids (3n)

Created by crossing tetraploids (4n) with diploids (2n), and they are usually sterile due to incomplete sets of chromosomes.

Colchicine

A chemical that can induce tetraploidy by disrupting microtubule polymerization during cell division.

Aneuploidy

A condition where the chromosome number deviates from the normal by part of a chromosome set.

Chromosomal rearrangements

Types include deletions, duplications, inversions, and translocations.

Meiosis in triploids

Issues arise due to the formation of aneuploid gametes which leads to sterility.

Tetraploids and fertility

Tetraploids are often fertile because functional 2n gametes can form due to pairing between homologous chromosomes.

Paracentric inversion during meiosis

Can result in deletion products.

Reciprocal-translocation heterozygote

Characterized by a 50% reduction in viable gametes or zygotes.

Down syndrome

Caused by trisomy of chromosome 21 (2n+1).

Gene dosage imbalance

Disrupts normal development, making aneuploids more abnormal than polyploids.

Sex chromosome aneuploidy examples

Turner syndrome (XO) or Klinefelter syndrome (XXY).