Imprinted genes:

Question

Imprinted genes:

BlackTom AI · Accepted Answer

Genomic imprinting is an epigenetic phenomenon in which one allele of a gene is expressed while the other allele is transcriptionally silenced depending on parental origin. Relevant concepts: epigenetic inheritance (heritable changes in gene expression without DNA sequence change), DNA methylation and histone modifications as imprinting marks, and differentially methylated regions (DMRs) or imprinting control regions that carry parent-specific methylation patterns.

Step-by-step reasoning:
1. Define imprinting: For an imprinted gene, the allele inherited from one parent is epigenetically marked so that only the allele from the other parent is expressed. The imprint (methylation/histone state) is established in the germline, maintained through cell divisions, and determines allele-specific expression after fertilization.
2. Link to epigenetic inheritance: Because imprinting relies on DNA methylation and chromatin states rather than changes in nucleotide sequence, it is a clear example of epigenetic inheritance — the silenced or active state is inherited by daughter cells. This confirms option A is true.
3. Link to DMRs: Imprinted loci characteristically have differentially methylated regions (DMRs) — regions showing methylation on one parental allele and not the other. These DMRs act as imprinting control regions that regulate allele-specific expression. This confirms option B is true.
4. Address option C: Imprinted genes are not “only transmitted by one parent.” Both parental alleles are transmitted to the offspring, but only one is expressed due to imprinting. Thus C is false (for example, IGF2 is paternally expressed while the maternal allele is present but silenced).
5. Options D and E: Since A and B are correct and C is incorrect, the correct combined choice is D (A and B). E (none) is wrong.

Therefore, the correct answer is D) A and B, matching the provided answer.

Imprinted genes:单项选择题

类似问题

The expression of a single allele is associated with which of the following?

The Igf2 gene is expressed from the paternal parent but not from the maternal parent. An ICR is located between the H19 and Igf2 genes. If a mutation eliminated this ICR, how would it affect the expression of the Igf2 gene?

Imprinted genes:

Genomic imprinting is an example of epigenetic inheritance.

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