Chromosomes


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Related to Chromosomes: Human chromosomes

Chromosomes

Spaghetti-like structures located within the nucleus (or central portion) of each cell. Chromosomes contain the genetic information necessary to direct the development and functioning of all cells and systems in the body. They pass on hereditary traits from parents to child (like eye color) and determine whether the child will be male or female.

chromosomes

carriers of genetic material in the nucleus of body cells. Each consists mainly of an elongated macromolecule of deoxyribonucleic acid (DNA). In human cells there are 23 pairs of chromosomes, each with a 'string' of hundreds to thousands of genes; one of each pair is derived from the germ cell (ovum or sperm) of each parent. One of the pairs are the sex chromosomes, known as 'XX' in the female, 'XY' in the male; splitting of the pairs in the formation of the germ cells in the gonads provides either an X or a Y chromosome in each sperm, so that combination with an X at fertilization determines the gender of the offspring.

chromosomes

48 gene-carrying intranuclear structures arranged as 24 pairs (23 identical pairs and one non-matched pair of sex chromosomes; male sex chromosome has 'X' and 'Y' components [XY]; female sex chromosome has two 'X' components [XX]); each pair of chromosomes reproduces itself during mitosis so that daughter cells each receive a full complement of 24 chromosome pairs; undergo reduction division during meiosis (i.e. ova or sperm formation) and each germ cell has only 24 single chromosomes (i.e. one chromosome from each of the 23 paired chromosomes, one chromosome from the dissimilar pair, as either an 'X' or a 'Y' chromosome; following fusion of ovum (X or X) with sperm (X or Y), the fertilized egg carries a full complement of 24 pairs of chromosomes, and the sex of the individual is determined at conception (XX or XY)

chromosomes (krō´məsōms),

n the small, dark-staining, and more or less rod-shaped bodies situated in the nucleus of a cell. At the time of cell division, chromosomes divide and distribute equally to the daughter cells. They contain genes arranged along their length. The number of chromosomes in the somatic cells of an individual is constant (the diploid number), whereas just half this number (the haploid number) appears in germ cells.
chromosome aberration,
n a rearrangement of chromosome parts as a result of breakage and reunion of broken ends.
References in periodicals archive ?
Since the discovery of maize B chromosomes by Kuwada (1925), they have been intensively studied.
Chromosome analysis revealed a mosaic 46,X,r(Y)[13]/45,X[11] karyotype with ring chromosome Y.
At least two species of rodents have already jettisoned their Y chromosomes entirely.
In the future, it may be possible to use this approach to take cells from a patient that has a defective chromosome with multiple missing or duplicated genes and rescue those cells by removing the defective chromosome and replacing it with a normal chromosome, said senior author Anthony Wynshaw-Boris, MD, PhD, James H.
Wilson Sayres from the University of California, Berkeley said that the Y chromosome has lost 90 percent of the genes it once shared with the X chromosome, and some scientists have speculated that the Y chromosome will disappear in less than 5 million years.
Chromosomes are relatively large molecules that, when spread out, can measure up to the length of an entire human arm.
Ring chromosomes are divided into two groups: those in which one normal chromosomal homologue is replaced by a ring equivalent, and those in which the ring chromosome is additional to the two normal copies of that chromosome; such a ring is termed a supernumary.
The simultaneous analysis ofB chromosomes and supernumerary segments variation in different populations offers the opportunity to analyze patterns of chromosome variation in nature.
strictum (HOVIN & HILL, 1966), there were described B chromosomes varying in number from one to eight in microsporocytes of the same plant.
In pre-reductional meiosis, which is the more common type, homologous chromosomes segregate in the first round of meiosis, and sister chromatids segregate in the second.
The pattern of meiosis in the Heteroptera varies between species, particularly for the behaviour of the sex chromosomes and the m chromosomes.