a karyotype with an extra set of chromosomes indicates
Polyploidy
title: Karyotype text: Karyotype A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in a species or in an individual organism and for a test that detects this complement or measures the number. Karyotypes describe the chromosome count of an organism and what these chromosomes look like under a light microscope. Attention is paid to their length, the position of the centromeres, banding pattern, any differences between the sex chromosomes, and any other physical characteristics. The preparation and study of karyotypes is part of cytogenetics. title: Karyotype text: full account of a karyotype may therefore include the number, type, shape and banding of the chromosomes, as well as other cytogenetic information. Variation is often found: The normal human karyotypes contain 22 pairs of autosomal chromosomes and one pair of sex chromosomes (allosomes). Normal karyotypes for females contain two X chromosomes and are denoted 46,XX; males have both an X and a Y chromosome denoted 46,XY. Any variation from the standard karyotype may lead to developmental abnormalities. Although the replication and transcription of DNA is highly standardized in eukaryotes, the same cannot be said for their karyotypes, which are title: Karyotype text: The study of whole sets of chromosomes is sometimes known as "karyology". The chromosomes are depicted (by rearranging a photomicrograph) in a standard format known as a "karyogram" or "idiogram": in pairs, ordered by size and position of centromere for chromosomes of the same size. The basic number of chromosomes in the somatic cells of an individual or a species is called the "somatic number" and is designated "2n". In the germ-line (the sex cells) the chromosome number is "n" (humans: n = 23). Thus, in humans 2n = 46. So, in normal diploid organisms, autosomal chromosomes are present in title: Karyotype text: of visible major chromosomal arms per set of chromosomes. Thus, FN ≤ 2 x 2n, the difference depending on the number of chromosomes considered single-armed (acrocentric or telocentric) present. Humans have FN = 82, due to the presence of five acrocentric chromosome pairs: 13, 14, 15, 21, and 22 (the human Y chromosome is also acrocentric). The fundamental autosomal number or autosomal fundamental number, "FNa" or "AN", of a karyotype is the number of visible major chromosomal arms per set of autosomes (non-sex-linked chromosomes). Ploidy is the number of complete sets of chromosomes in a cell. Aneuploidy is the condition title: Karyotype text: in which the chromosome number in the cells is not the typical number for the species. This would give rise to a chromosome abnormality such as an extra chromosome or one or more chromosomes lost. Abnormalities in chromosome number usually cause a defect in development. Down syndrome and Turner syndrome are examples of this. Aneuploidy may also occur within a group of closely related species. Classic examples in plants are the genus "Crepis", where the gametic (= haploid) numbers form the series x = 3, 4, 5, 6, and 7; and "Crocus", where every number from x = 3 to