Genetics as it applies to evolution, molecular biology, and medical aspects.
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Is it true that gene and chromosomal mutation are similar in the sense that they both can occur through translocation? Can an increase in genetic material occur in both then? Are chromosomal mutations due more often to mitosis or meiosis?
Hi, translocation is a type of chromosomal mutation where a part of one non-homologus chromosome join on to another chromosome this does not occur in genes directly howver translocation disrupts genes and translocates genes as a result of occuring in a chromosomal mutation.
Now, this is based on my opinion but dont take my word on it sorry. Translocation occurs with existing genetic material and thus it doesnt "increase" the amount of genetic material but rather diversifies it/variation.
Yes, mutation can occur thru translocation in both genes (the individulal alleles or its fragment) and chromosomes. I do not believe an increase in genetic material occurs as it is just a translocation of genetic material.
Now transposons can increase genetic material, thus providing the "junk" DNA in all genomes. And they also jump all over the DNA, mutating it here and there. They are fun to study.
Chromosomal translocation mutations can happen whenever the chromosomes come into contact with other chromosomes. This could be during mitosis or meiosis. The manifestation of the expression of the translocation can be observed in mitosis in which one cell has the translocation mutation, and then if it can be viable and reproduce, it can then invade the organism. Examples can be Buritt's lymphoma (translocation of the BCL-gene : http://en.wikipedia.org/wiki/Burkitt's_lymphoma). But if it is in meiosis, then the whole genome of the organism is affected by the translocation mutation, such as Down Syndrome/Trisomy 21(http://en.wikipedia.org/wiki/Down_syndrome).
The extra chromosome 21 material that causes Down syndrome may be due to a Robertsonian translocation in the karyotype of one of the parents. In this case, the long arm of chromosome 21 is attached to another chromosome, often chromosome 14 or itself (called an isochromosome). A person with such a translocation is phenotypically normal. During reproduction, normal disjunctions leading to gametes have a significant chance of creating a gamete with an extra chromosome 21. Translocation Down syndrome is often referred to as familial Down syndrome. It is the cause of 2–3% of observed cases of Down syndrome.
95% of the observed cases of Trisomy 21 is anueploidy caused by meiotic nondisjunction events in the parental gametes (88% in the female gamete, and 7% in the male gamete).
It seems as if a translocation could occur that would add information - a piece moves to another chromosome from a source, and then the added-to chromosome winds up in a gamete with the source chromosome's unmutated homologous match. Offspring gets a chromosome with extra material, but that material is also in the "original."
6 posts • Page 1 of 1
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