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M2M Unit II > Genetic Imprinting > Flashcards

Genetic Imprinting Flashcards

1
Q

Prader-Willi syndrome is characterized by _____.

A

obesity, excessive and indiscriminate eating, short stature, small hands and feet, hypogonadism, and intellectual disabilities

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2
Q

imprinting

A

genes that are functionally hemizygous because one parental allele is silenced; a sex-dependent epigenetic modulation

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3
Q

The imprinted genes encode both ________ and ________.

A

proteins and non-coding RNAs

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3
Q

The inherited form of _________ is exclusively inherited from mothers

A

Angelman syndrome

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4
Q

DNA methylation is maintained in __________.

A

somatic cells after fertilization

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4
Q

uniparental disomy

A

inheriting two copies of a chromosome from one parent, or no copies from one parent

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4
Q

Uniparental disomy most commonly occurs when a trisomic conceptus loses one of its extra chromosomes due to _______.

A

mitotic nondisjunction in early gestation

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6
Q

What is one sex-dependent epigenetic modulation mechanism?

A

imprinting

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6
Q

Angleman Syndrome patients have a deletion of approximately the same region of chromosome 15 as Prader-Willi patients but on the _____ derived homolog.

A

maternally

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7
Q

_________ is characterized by obesity, excessive and indiscriminate eating, short stature, small hands and feet, hypogonadism, and intellectual disabilities.

A

Prader-Willi syndrome

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7
Q

The 15q11-q13 region contains ____ paternally expressed genes.

A

three

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7
Q

Uniparental disomy most commonly occurs when a trisomic conceptus loses _______ due to mitotic nondisjunction in early gestation.

A

one of its extra chromosomes

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7
Q

Demethylation could result from the inhibition of _____, or indirectly through the inactivation of chromatin-remodeling proteins.

A

the maintenance methyltransferase, DNMT1

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9
Q

How many human genes are imprinted?

A

about 1%

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11
Q

How does CpG methylation affect gene expression?

A

chromatin structure is compacted to repress transcription

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11
Q

DNA methylation is established _________.

A

in the gamete

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13
Q

DNA methylation is the epigenetic mark that mediates __________.

A

genetic imprinting

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14
Q

Which chromosome is mutated to result in Prader-Willi and Angleman Syndrome?

A

15

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15
Q

To accomplish such epigenetic inheritance, parental patterns of methylation are erased in ______ as part of overall genomic reprogramming.

A

primordial germ cells

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16
Q

The chromosomal sorting error in uniparental disomy “rescues” the developing pregnancy from spontaneous abortion but may result in an abnormal phenotype if both remaining homologs are derived from _______.

A

the same parent

16
Q

15q11-13 locus relevance

A

uniparental disomy - Prader-Willi and Angelman Syndrom

17
Q

________ could result from the inhibition of the maintenance methyltransferase, DNMT1, or indirectly through the inactivation of chromatin-remodeling proteins.

A

Demethylation

18
Q

epigenetic

A

mitotically and meiotically inheritable variation in gene expression that is not caused by a change in DNA sequence

18
Q

In addition to parent of origin effects due to deletions, genetic imprinting also leads to abnormal phenotypes in association with ______.

A

uniparental disomy

20
Imprinted gene clusters contain both _____ and ______ imprinted genes.
maternally and paternally
21
In uniparental disomy, if both remaining 15 homologs are maternal in origin, both carry maternally repressed loci, but normal development is dependent on expression of genes at the missing \_\_\_\_\_\_\_.
paternal locus
21
Which trisomies can survive to live birth?
13, 18, and 21
22
DNA methylation is __________ so that it can be reset during gametogenesis.
reversible
23
Erasure and resetting of the imprint appears to occur at \_\_\_\_\_\_\_.
imprinting centers (IC)
24
What would happen if methylation marks are not erased during gametogenesis?
total silencing of both copies of the gene would occur at a very high rate
26
\_\_\_\_\_\_ is characterized by an unusual facial appearance, short stature, severe intellectual disabilities, spasticity, and seizures.
Angelman syndrome
28
What enzyme methylates a histone?
histone methyltransferase
29
Where is the promoter region normally found?
near the centromere
31
New, sex-dependent imprints (patterns of methylation) are initiated during \_\_\_\_\_\_\_\_\_\_\_.
gametogenesis
32
In 70% of Prader-Willi patients, the syndrome is the result of a cytogenetically observable _____ involving the long arm of chromosome 15 (15q11-q13), occurring on the chromosome 15 homolog inherited from the patient’s \_\_\_\_\_.
deletion; father
33
What recognizes hemi-methylated DNA strands and methylates the newly synthesized strand?
maintenance methyltransferase
34
What is the job of a maintenance methyltransferase?
recognize hemi-methylated DNA strands and methylate the newly synthesized strand
35
\_\_\_\_\_\_\_\_\_\_\_ is the epigenetic mark that mediates genetic imprinting.
DNA methylation
37
Which two syndromes are caused by maintenance of methylation marks during gametogenesis?
1) Prader-Willi 2) Angleman syndrome
38
Imprinting centers (IC) contain non-coding DNA sequences that bind imprinter _____ and recruit DNA methyltransferase (DNMT) complexes that methylate CpG islands located near the IC on the same chromosome (cis).
RNA transcripts (BD transcripts)
39
\_\_\_\_\_\_\_\_\_\_ is when genes are functionally hemizygous because one parental allele is silenced.
Imprinting
41
\_\_\_\_\_\_\_\_ most commonly occurs when a trisomic conceptus loses one of its extra chromosomes due to mitotic nondisjunction in early gestation.
Uniparental disomy
42
Demethylation could result from the inhibition of the maintenance methyltransferase, DNMT1, or indirectly through the \_\_\_\_\_\_\_.
inactivation of chromatin-remodeling proteins
43
Two epigenetic mechanisms?
1) reversible, post-translational modifications of histones 2) DNA methylation
44
Mutations at ______ are heritable lesions that can generate the same abnormal phenotypes as deletions or uniparental disomies.
imprinting centers
46
What is the molecular basis for genetic imprinting?
Methylation of cytosine residues in CpG residues of promoter regions
47
Once sex-specific patterns of methylation are established during gametogenesis, the patterns are retained in somatic cells by \_\_\_\_\_\_\_.
maintenance methylation
48
15q11-q13 region genes encode proteins for \_\_\_\_\_\_.
placental development, fetal growth

M2M Unit II (21 decks)

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