Medical term:

translocation

[trans″lo-ka´shun]

the attachment of a fragment of one chromosome to a nonhomologous chromosome.

Translocation of a portion of one chromosome to another chromosome. Redrawn from Damjanov, 2000.

reciprocal translocation the mutual exchange of fragments between two broken chromosomes, one part of one uniting with part of the other.

robertsonian translocation that in which the breaks occur at the centromeres and entire chromosome arms are exchanged, usually involving two acrocentric chromosomes.

trans·lo·ca·tion

(trans'lō-kā'shŭn),

1. Transposition of two segments between nonhomologous chromosomes as a result of abnormal breakage and refusion of reciprocal segments.

2. Transport of a metabolite across a biomembrane.

[trans- + L. location, placement, fr. loco, to place]

Farlex Partner Medical Dictionary © Farlex 2012

translocation

(trăns′lō-kā′shən, trănz′-)

1. A change of location.

2. Genetics

a. A transfer of a chromosomal segment to a new position, especially on a nonhomologous chromosome.

b. A chromosomal segment that is translocated.

trans·lo·ca·tion

(trans'lō-kā'shŭn)

1. Transposition of two segments between nonhomologous chromosomes as a result of abnormal breakage and refusion of reciprocal segments.

2. Transport of a metabolite across a biomembrane.

[trans- + L. location, placement, fr. loco, to place]

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

translocation

1. A form of chromosome mutation in which a detached part of a CHROMOSOME becomes attached to another chromosome or parts of two chromosomes may be joined. Translocations may be inherited or acquired. In many cases they cause no effect on the body because all the normal chromosomal material is present. But if a translocation results in a deficiency or excess of chromosomal material the results are serious.

2. Of a gene when a new copy of the gene appears at a location on the genome remote from the original location.

3. The movement of a RIBOSOME along a MESSENGER RNA molecule from one CODON to the next.

4. Of the movement of a protein across a membrane.

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

translocation

the transport of organic substances in the PHLOEM of higher plants, the mechanism for which is not fully understood. A popular theory is by MASS FLOW but there is evidence that there is active uptake of solutes into the sieve tubes of phloem involving the use of ATP. There may also be movement of solutes along the protein filaments which stretch from one sieve element to the next via the sieve plates, using a form of CYTOPLASMIC STREAMING.
a type of CHROMOSOMAL MUTATION in which non-HOMOLOGOUS CHROMOSOMES break and exchange pieces. During the process, pieces of chromosomes can be lost or gained, causing serious problems, particularly with gamete viability. see TRANSLOCATION HETEROZYGOTE.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

Translocation

The transfer of one part of a chromosome to another chromosome during cell division. A balanced translocation occurs when pieces from two different chromosomes exchange places without loss or gain of any chromosome material. An unbalanced translocation involves the unequal loss or gain of genetic information between two chromosomes.

Mentioned in: Down Syndrome, Patau Syndrome, Prader-Willi Syndrome

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.

mutation

A permanent transmissible change in the nucleotide sequence of the DNA within a gene, or a change in the physical structure of a chromosome. It can occur by substitution (one base or nucleotide is replaced by another), transition (a purine (adenine or guanine) is replaced by another purine or one pyrimidine (cytosine or thymine) is replaced by another pyrimidine), transversion (a pyrimidine is replaced by a purine or vice versa), deletion or insertion of one or more bases. Mutations can also occur in a chromosome as a result of inversion (a segment of chromosome is inserted in reverse order), deletion (a loss of a piece of chromosome) or translocation (a piece of chromosome attaches to another). Mutations result in the formation of a protein with an abnormal amino acid or an absence of the protein and these may result in disease but some mutations may be beneficial. Mutations may be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation (X-rays, gamma rays), carcinogens, viruses, or spontaneously. See chromosome; gene.

trans·lo·ca·tion

(trans'lō-kā'shŭn)

1. Transposition of two segments between nonhomologous chromosomes as a result of abnormal breakage and refusion of reciprocal segments.

2. Transport of a metabolite across a biomembrane.

[trans- + L. location, placement, fr. loco, to place]

translocate

(trăns-lō′kāt′, trănz-)

tr.v. translo·cated, translo·cating, translo·cates

1. To cause to change from one place or position to another; displace.

2. To transfer (a chromosomal segment) to a new position; cause to undergo translocation.

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