JM asked in Science & MathematicsBiology · 1 decade ago

Help! genomic imprinting?

if maternal imprinting occurs, does the mom imprint, or inactivate, the her gene therefore father's gene is expressed? or does she imprint, or inactivate, the father's gene therefore her genes are expressed?


2 Answers

  • 1 decade ago
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    I hear you on the confusion, this topic is actually a pretty advanced subject in evolution and the actual mechanisms and reason for the evolution of genomic imprinting are still debated.

    Genomic imprinting is the differiental expression of gene depending on whether it is inherited from maternally(from the mother) or paternally(from the father). I assume your question referrs to mammals (as the situation is a bit different in plants an insects), but in the case of mammals, you know that an offspring typically inherits a chromosome from each parent. In a "normal" situation, the mother's and father's genes should be expressed equally. Genomic imprinting implies that either the maternal gene is being expressed instead of the paternal or the paternal gene is being expressed instead of the maternal one.

    This is how it more-or-less works in a SIMPLE situation: if, for example, gene "A" is maternally imprinted gene, then the offspring's gene that is expressed will ONLY be the A gene that came from the mother and the paternal A gene may be repressed (inactive). BUT there are also paternally imprinted genes. So if there is another (for example) gene B, is paternally inherited, then only the B gene of the father will be expressed and the B gene of the mother may be repressed.

    So basically, an genomic imprinting is like having a "stamp" on a gene that indicates where the gene has come from (mother or father) and this "stamp" indicates that this is the gene (mother or father) that should be expressed.

    However, it is possible to have genomic imprintings (one from mom and the other from dad) on the same chromosomal region in humans so that each imprinting is important for development. The classic example is Prader-Willi and Angelman Syndrome. In this example, both maternal and paternal imprinting on a specific part of chromsome 15 is necessary for "normal" development. If the paternal imprinting is missing (due to a chromsomal deletion), then the individual develops the symptoms of Prader-Willi Syndrome but if the maternal imprinting is missing, Angelman Syndrome results.

    So in sum, it is possible to have imprinting from both mom AND dad that may both be important in development as well as cases where either only the maternal or paternally inherited gene is expressed.

  • 1 decade ago

    Maternal imprinting means that an allele inherited from the mother is not expressed in offspring.

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