sex chromosome


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sex chromosome

n.
Either of a pair of chromosomes in diploid cells, or a single chromosome in haploid cells, carrying genes that determine the sex and sex-linked characteristics of an organism. Most mammals, including humans, have one pair of sex chromosomes in diploid cells, designated XX in females and XY in males.

sex chromosome

a chromosome that determines the sex of individuals; it carries genes that transmit sex-linked traits and conditions. In humans and other mammals there are two distinct sex chromosomes, designated X and Y, which appear in females as XX and in males as XY. Compare autosome.

sex chromosome

or

heterosome

one of a pair of chromosomes that is different in the two sexes and is involved in SEX DETERMINATION. All remaining chromosomes in a KARYOTYPE are called AUTOSOMES. In most organisms, such as mammals and DIOECIOUS plants, the female contains two identical X-chromosomes and is the HOMOGAMETIC SEX while the male contains one X and one Y-chromosome and is the HETEROGAMETIC SEX. In birds, butterflies and moths, some fish and certain plants, the situation is reversed in the two sexes. Genes located on sex chromosomes are described as showing SEX LINKAGE.

chromosome 

One of the thread-like structures located within the cell nucleus composed of an extremely long, double-stranded DNA (deoxyribonucleic acid) helix tightly folded around proteins called histones. Each chromosome carries genes that contain the hereditary material that controls the growth and characteristics of the body. There are 46 chromosomes in each human somatic cell organized in 23 pairs, of which 22 pairs are similar in appearance but differ at the molecular level. They are called autosomal chromosomes or autosomes and are designated by a number (with chromosome 1 being the longest, followed by chromosome 2, etc.). The other pair, the sex chromosomes determines the sex of the individual. In mammals the two sex chromosomes of females are alike (homologous) and are referred to as X chromosomes. Males carry one X chromosome along with a much shorter chromosome, the Y chromosome. Each chromosome has a centromere that divides it into two arms, the short arm 'p' and the long arm 'q'. Disorders of chromosome number in which the number of chromosomes is above or below the normal (46) are called aneuploidy. Common forms of aneuploidy are trisomy in which there is one extra chromosome and monosomy in which there is one less, than the normal 46. They rarely cause specific eye diseases but affected individuals present ocular manifestations. Examples: Down's syndrome (trisomy of chromosome 21), Edwards' syndrome (trisomy 18), Turner's syndrome (monosomy 45 XO). There are other chromosome abnormalities such as translocation (one segment of a chromosome is transferred to another chromosome) as may occur in congenital anterior polar cataract, deletion (a loss of a piece of chromosome) as in aniridia, choroideremia, retinoblastoma, etc. Other cases involve damage of a chromosome (e.g. fragile X syndrome). See defective colour vision; gene; mitosis; mutation.
References in periodicals archive ?
After detailed history and examination, the current approach is to (a) identify the sex chromosome complement by karyotype analysis or FISH with X and Y probes and chromosome microarray; (b) gather additional phenotypic information by complete metabolic and endocrine testing as well as imaging studies, and (c) genetic testing for copy number variants in regions associated with known DSD genes or gene sequencing either for single candidate gene or a gene panel.
While only a small percentage of teleosts have morphologically distinguishable sex chromosomes, those that do display a variety of kinds (Kitano and Peichel, 2012) with the X1X2Y-X1X1X2X2 system being the most prevalent.
The presence of sex chromatin in this species is a useful parameter for monitoring the effect of radiation, as its morphology and quantity can be used as a marker to identify sex chromosome aberrations (Makee & Tafesh 2006).
Recently, 48,XXYY syndrome has been accepted to be a different picture like some other rare sex chromosome aneuploidies (48,XXXY and 48,XXXXY).
I used conventional methods of polytene chromosome analysis (Shields and Procunier, 1982; Shields, 2013) to determine the sex chromosome constitution of larvae of the S.
In a training panel of 1546 cases, dual classification of the fetal sample by sex, followed by assessment of sex chromosome complement, provided an overall sensitivity of 100% (95% CI 82.
Psychosocial Competence of unselected young adults with sex chromosome abnormalities.
Therefore, we can say very comfortably that CMA is a 100% comparison with karyotyping for common autosomal and sex chromosome aneuploidies.
In the second meiotic division only one daughter cell received a sex chromosome in telophase II.
Seventy-five percent of women with Turner's syndrome have their mother's X, which means that they have no sex chromosome from their father.
6,10) For example, individuals with only one X sex chromosome have a female appearance (Turner's syndrome), while individuals with two X and one Y chromosome (XXY, Klinefelter's syndrome) are usually infertile men.