Chromosome / chromosomal

The chromosome on which the gene can be found. The first number or letter used to describe a gene s location represents the chromosome. Chromosomes 1 through 22 (the autosomes) are designated by their chromosome number. The sex chromosomes are designated by X or Y. 

This chapter reviews diseases that are caused by microscopically observable alterations in chromosomes. These alterations may involve the presence of extra chromosomes or the loss of chromosomes. They may also consist of structural alterations of chromosomes. Chromosome abnormalities are seen in approximately 1 in 150 live births and are the leading known cause of mental retardation. The vast majority of chromosome abnormalities are lost prenatally chromosome abnormalities are seen in 50% of spontaneous fetal tosses during the first trimester of pregnancy, and they are seen in 20% of fetuses lost during the second trimester. Thus, chromosome abnormalities are the leading known cause of pregnancy loss. 

The clinical implications of both amplification and loss in tumors have been studied. In a study of 29 Dukes C colorectal cancer patients, those with tumors that had two or more chromosomal regions of gain or loss had significantly better prognosis than patients with less (p = 0.02) (21). Loss of chromosome 5q and lack of 8q amplification in serous ovarian cancer n = 96) is associated with improved prognosis (5-year survival of 75% versus 0% with no loss on 5q and amplification on 8q p = 0.0007) (22). In childhood ALL the amplification of specific chromosomes, chromosome regions, and genes has been associated with chemotherapy resistance and clinical outcome (23,24). 

DNA is found in the nucleus of cells. In a cell that is not dividing, the DNA is in a dispersed form called chromatin. When the cell is preparing to divide, the chromatin reorganizes itself, forming pairs of thick, rodlike chromosomes. Chromosomes consist of DNA and protein. The genes, which control heredity, are positioned along the DNA in the chromosomes. Each gene consists of a specific section of DNA and directs the synthesis of a specific protein. 

Genome DNA with nonhistone protein genome in nucleoid, not surrounded by membrane DNA complexed with histone and nonhistone proteins in chromosomes chromosomes in nucleus with membranous envelope... 

HOMOLOGOUS CHROMOSOMES Chromosomes occurring in pairs, one derived from each of two parents, normally (except for sex chromosomes) morphologically alike and bearing the same gene loci each member of such a pair is the homologue of the other. 

Because of the heterogeneous molecular nature of HS (Table 6-2), the HS genes can be assigned to several chromosomes chromosome 1 (a-spectrin), chromosome 8 (ankyrin), chromosome 14 ((3-spectrin), chromosome 15 (protein 4.2), and chromosome 17 (band 3). The... 

Figure 6.9. Recombination among chromosomes. Chromosomes being transmitted from grandparents (A) to a parent (B), along with examples of gametes that could be passed along to an offspring (C). The third possibility in part C represents a recombined chromosome, which is composed of one piece originally derived from the grandfather and one piece derived from the grandmother.

Homologous chromosomes. Chromosomes that carry the same pattern of genes, but not necessarily the same alleles. 

Serotransferrin receptor genes are encoded on the same chromosome (chromosomal region 3q21-3q29) in humans [131,132] as those for sero- and melanotransferrins (for a review, see ref [88]). 

Genetic code and operators. Each individual of a population is coded by a chromosome. Chromosomes have to be decoded to obtain a proper phenotype and to calculate the fitness of each member. Usually, bitstrings are... 

Federico C., Andreozzi L., Saccone S., Bernardi G. (2000). Gene density in the Giemsa bands of human chromosomes. Chromosome Res. 8 737-746. 

Hori T., Suzuki Y., Solovei I., Saitoh Y., Hutchison N., Ikeda J.E., Macgregor H., Mizuno S. (1996). Characterization of DNA sequences constituting the terminal heterochromatin of the chicken Z chromosome. Chromosome Res. 4 411-426. 

Mutagen A material that induces genetic changes (mutations) in the DNA of chromosomes. Chromosomes are the blueprints of life within individual cells. 

Chromosomal alterations refer to changes in number and structure of chromosomes. They may involve loss or gain of entire chromosomes, chromosome breaks, nondisjunctions, and translocations. These abnormalities are detected by searching for chromosomal changes either in somatic or germinal cells. 

Cholinergic—stimulated by or releasing acetylcholine or a related compound Cholinesterase—enzyme that hydrolyzes acetylcholine into choline and acetic acid and is important in the functioning of the nervous system Chromatid—one of the two spiral filaments making up the chromosome Chromosomes—structures in the cell nucleus that contain DNA Chronic effect—biological change persisting over a major portion of a lifetime... 

We know from studies on the recessive lethal mutations induced in the ad-3 region (de Serres and Osterbind, 1962 de Serres, 1964, 1968 Webber and de Serres, 1965) that recessive lethal mutations result from both alteration of the gene (point mutation) and physical removal of the gene from the chromosome (chromosome deletion). In the latter case, the mutations are haploid lethal even on supplemented media, most probably because other genes with nonsupplementable loss of function are simultaneously deleted. 

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