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cis-trans effect
Значение термина cis-trans effect в knolik
cis-trans effect - cis-trans effect
cis-trans effect - Two mutations at non-corresponding places somewhere in a given pair of homologous chromosomes (within the cells of a diploid organism) can be in either of two arrangements. Both mutations may be on one chromosome of the pair, the homologous chromosome being normal (cis arrangement); or each member of the pair carries one of the mutations (trans arrangement). Similarly, two types of heterokaryon are possible, the cis heterokaryon where both mutations are carried in the same nucleus, and the trans heterokaryon, where the two mutations are in different nuclei. If the two mutations are in functionally different parts of the given pair of chromosomes (i.e. in different cistrons), the cis and trans arrangements will not be phenotypically different; since a normal functional unit (cistron) would be present in one of the pair of homologous chromosomes, ensuring a normal gene product, say a particular enzyme: the mutations behave as classical recessives. In these circumstances, when the mutations are in the trans arrangement, complementation is said to occur between the two chromosomes, each supplying the deficiency of the other. The outcome is otherwise when the two mutations lie in different parts of a given pair of homologous functional units (cistrons). In the cis arrangement, one of the pair of functional units, and hence the organism, will be normal. But in the trans arrangement the functional unit concerned is defective in both chromosomes and there will be no normal gene product, no complementation. This difference of effect of the cis and trans arrangements is the ds-trans effect. It follows that a functional unit of a chromosome or cistron may be defined, and was originally defined, simply by means of breeding experiments, as a length of chromosome (or DNA) within which a cis-trans effect occurs, or within which complementation does not occur.
Рядом со словом cis-trans effect в knolik
| cisternae | В начало буква "" буквосочетание "" | cistron |
Статья про cis-trans effect была прочитана 246 раз
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