Chromosome (redirected from lampbrush chromosome)

chromosome /chro·mo·some/ (kro´mah-som) in animal cells, a structure in the nucleus containing a linear thread of DNA which transmits genetic information and is associated with RNA and histones; during cell division the material composing the chromosome is compactly coiled, making it visible with appropriate staining and permitting its movement in the cell with minimal entanglement; each organism of a species is normally characterized by the same number of chromosomes in its somatic cells, 46 being the number normally present in humans, including the two (XX or XY) which determine the sex of the organism. In bacterial genetics, a closed circle of double-stranded DNA which contains the genetic material of the cell and is attached to the cell membrane; the bulk of this material forms a compact bacterial nucleus.chromoso´mal

Chromosome. (A), Long, threadlike interphase chromatin in nucleus. (B), Giemsa-stained, partially condensed chromatid in late prophase. (C), Giemsa-stained, fully condensed chromatid in metaphase; note that some of the sub-bands visible in late prophase have condensed into single bands. (In B and C, only one of a pair of sister chromatids is shown.)

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bivalent chromosome  see bivalent (2).

homologous chromosomes  a matching pair of chromosomes, one from each parent, with the same gene loci in the same order.

Ph1 chromosome , Philadelphia chromosome an abnormality of chromosome 22, characterized by shortening of its long arms (the missing portion probably translocated to chromosome 9); present in marrow cells of patients with chronic granulocytic leukemia.

ring chromosome  a chromosome in which both ends have been lost (deletion) and the two broken ends have reunited to form a ring-shaped figure.

sex chromosomes  those associated with sex determination, in mammals constituting an unequal pair, the X and the Y chromosome.

somatic chromosome  autosome.

X chromosome  a sex chromosome, carried by half the male gametes and all female gametes; female diploid cells have two X chromosomes.

Y chromosome  a sex chromosome, carried by half the male gametes and none of the female gametes; male diploid cells have an X and a Y chromosome.

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chro·mo·some (krm-sm)

n.

1. A threadlike linear strand of DNA and associated proteins in the nucleus of animal and plant cells that carries the genes and functions in the transmission of hereditary information.

2. A circular strand of DNA in bacteria and cyanobacteria that contains the hereditary information necessary for cell life.

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chromo·somal (-sml), chromo·somic (-smk) adj.

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Chromosome

A structure composed of deoxyribonucleic acid (DNA) contained within a cell's nucleus (center) where genetic information is stored. Human have 23 pairs of chromosomes, each of which has recognizable characteristics (such as length and staining patterns) that allow individual chromosomes to be identified. Identification is assigned by number (1-22) or letter (X or Y).

Mentioned in: Acoustic Neuroma, Amniocentesis, Birth Defects, Cerebral Amyloid Angiopathy, Cri Du Chat Syndrome, Down Syndrome, Edwards' Syndrome, Fragile X Syndrome, Gene Therapy, Genetic Testing, Hereditary Hemorrhagic Telangiectasia, Huntington Disease, Klinefelter Syndrome, Neurofibromatosis, Patau Syndrome, Retinoblastoma, Turner Syndrome, Von Willebrand Disease, Wilson Disease

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chromosome

in animal cells, a structure in the nucleus, containing a linear thread of deoxyribonucleic acid (DNA), which transmits genetic information and is associated with ribonucleic acid and histones.

During cell division the material composing the chromosome is compactly coiled, making it visible with appropriate staining and permitting its movement in the cell with minimal entanglement. Each organism of a species is normally characterized by the same number of chromosomes in its somatic cells. The diploid numbers (number of total chromosomes per cell) are cattle—60, sheep—54, horse—64, donkey—62, pig—38, dog—78, cat—38, human—46. The chromosomes are arranged in pairs and one of the pairs is the sex chromosomes (XX or XY), which determines the sex of the organism. See also heredity.

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compound chromosome

a genetic engineering procedure which produces two chromosomes in one of which the left arms of the two original chromosomes are joined together and the two original right arms are also joined together; used in genetic control of insect populations.

homologous c's

the chromosomes of a matching pair in the diploid complement that contain alleles of specific genes.

lampbrush chromosome

so named because of the bristling appearance given them by many open loops of chromatin along the extended chromosome.

ring chromosome

a chromosome in which both ends have been lost (deletion) and the two broken ends have reunited to form a ring-shaped figure.

sex c's

the chromosomes responsible for determination of the sex of the individual that develops from a zygote, in mammals constituting an unequal pair, the X and the Y chromosome.

somatic chromosome

autosome.

submetacentric chromosome

see submetacentric.

W chromosome

sex chromosome in animals such as poultry in which the female is the heterogametic state, the male has the ZZ genotype and the female the ZW genotype.

X chromosome

the female sex chromosome, being carried by half the male gametes and all female gametes; female diploid cells have two X chromosomes, the male has the XY genotype.

Y chromosome

the male sex chromosome, being carried by half the male gametes and none of the female gametes; male diploid cells have an X and a Y chromosome; females carry the XX genotype.

Z chromosome

sex chromosome in animals, such as poultry, in which the female is the heterogametic sex; the male has the ZZ genotype and the female the ZW genotype.