Podcast
Questions and Answers
What is the function of the imprinting control region (ICR) in genomic imprinting?
What is the function of the imprinting control region (ICR) in genomic imprinting?
- To activate transcription of the imprinted gene
- To bind transcription factors that regulate the imprinted gene (correct)
- To methylate the imprinted gene in both oocyte and sperm
- To demethylate the imprinted gene
What happens to methylation in gamete-forming cells?
What happens to methylation in gamete-forming cells?
- Methylation is replaced by histone modification
- Methylation is removed (correct)
- Methylation is maintained
- Methylation is inherited from the parent
What is the result of methylation on gene transcription?
What is the result of methylation on gene transcription?
- Inhibition of transcription (correct)
- No effect on transcription
- Variable effect on transcription
- Activation of transcription
What is the unit of genomic imprinting?
What is the unit of genomic imprinting?
What is the purpose of genomic imprinting in some species?
What is the purpose of genomic imprinting in some species?
In which cells is the pattern of methylation maintained?
In which cells is the pattern of methylation maintained?
What is the main purpose of dosage compensation?
What is the main purpose of dosage compensation?
What is a characteristic of epigenetic inheritance?
What is a characteristic of epigenetic inheritance?
During which stages of development can epigenetic changes occur?
During which stages of development can epigenetic changes occur?
What is the mechanism of dosage compensation in placental mammals?
What is the mechanism of dosage compensation in placental mammals?
What is an example of a species where the X chromosome from the male parent is inactivated?
What is an example of a species where the X chromosome from the male parent is inactivated?
Why does dosage compensation occur?
Why does dosage compensation occur?
What type of modifications can cause epigenetic changes?
What type of modifications can cause epigenetic changes?
What is the significance of epigenetic inheritance?
What is the significance of epigenetic inheritance?
What is the primary function of the Xic during X-chromosome inactivation?
What is the primary function of the Xic during X-chromosome inactivation?
Which of the following statements about genomic imprinting is TRUE?
Which of the following statements about genomic imprinting is TRUE?
What is the effect of the Igf2− allele on the size of a mouse?
What is the effect of the Igf2− allele on the size of a mouse?
What is the percentage of X-linked genes in humans that may escape full inactivation?
What is the percentage of X-linked genes in humans that may escape full inactivation?
Which of the following genes is an example of genomic imprinting in the mouse?
Which of the following genes is an example of genomic imprinting in the mouse?
What is the term used to describe the phenomenon of genes being expressed from only one parent?
What is the term used to describe the phenomenon of genes being expressed from only one parent?
What is the mechanism thought to be involved in the escape of X-linked genes from inactivation?
What is the mechanism thought to be involved in the escape of X-linked genes from inactivation?
Which of the following is a characteristic of genomic imprinting?
Which of the following is a characteristic of genomic imprinting?
Flashcards
Epigenetic Inheritance
Epigenetic Inheritance
A change in gene expression without altering the DNA sequence.
Dosage Compensation
Dosage Compensation
Balancing gene expression differences between sexes with different sex chromosome numbers.
Genomic Imprinting
Genomic Imprinting
Gene expression depends on whether the gene came from the mother or father, not both.
X-Chromosome Inactivation
X-Chromosome Inactivation
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Monoallelic Expression
Monoallelic Expression
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Methylation
Methylation
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Imprinting Control Region (ICR)
Imprinting Control Region (ICR)
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Oogenesis
Oogenesis
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Spermatogenesis
Spermatogenesis
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allele
allele
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somatic cells
somatic cells
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pseudoautosomal genes
pseudoautosomal genes
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early embryonic development
early embryonic development
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Igf2 gene
Igf2 gene
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Gamete-forming cells
Gamete-forming cells
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Gene expression
Gene expression
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Paternal allele
Paternal allele
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Maternal allele
Maternal allele
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inactivated X chromosome
inactivated X chromosome
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DNA modifications
DNA modifications
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Study Notes
Epigenetic Inheritance
- Epigenetic inheritance refers to a pattern in which a modification occurs to a nuclear gene or chromosome, altering gene expression, but the DNA sequence remains unchanged.
- Epigenetic changes are caused by DNA and chromosomal modifications that can occur during oogenesis, spermatogenesis, or early embryonic development.
Dosage Compensation
- Dosage compensation offsets differences in the number of active sex chromosomes.
- It has been studied in mammals, Drosophila, and Caenorhabditis elegans, with different mechanisms depending on the species.
- In placental mammals, one of the X chromosomes in somatic cells of females is inactivated, or the X chromosome from the male parent is inactivated, or either of the two X chromosomes is randomly inactivated.
Genomic Imprinting
- Genomic imprinting occurs in several species, including insects, mammals, and flowering plants, involving a single gene, part of a chromosome, an entire chromosome, or all chromosomes from one parent.
- It can be used for X inactivation in some species.
- Imprinting involves a marking process, with an imprinting control region (ICR) located near the imprinted gene, which is methylated either in the oocyte or sperm, but not both.
- For most genes, methylation causes inhibition of transcription.
Pattern of Methylation and X-Chromosome Inactivation
- Each parent inherits one methylated and one unmethylated gene, which is maintained in somatic cells, and methylation is removed in gamete-forming cells.
- The inactivated X chromosomes is maintained as such during subsequent cell divisions.
- Some genes on the inactivated X chromosome are expressed in somatic cells of adult female mammals, including pseudoautosomal genes, which do not require dosage compensation.
Genomic Imprinting and Gene Expression
- Genomic imprinting results in the expression of either the maternally-inherited or the paternally-inherited allele, but not both, a phenomenon known as monoallelic expression.
- The Igf2 gene in mice is an example of genomic imprinting, where the paternal allele is transcribed into RNA, but the maternal allele is not.
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