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Fundamentals of Medicine: Exam II > Epigenetics > Flashcards

Epigenetics Flashcards

1
Q

6 steps to control eukaryotic gene expression:

A

transcriptional control, RNA processing, RNA transport, translational control, mRNA degradation, and protein processing

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2
Q

Most Epigenetics takes place during ____ control

A

Transcription

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3
Q

_____ is heritable changes in gene expression that don’t involve changes to the underlined DNA sequence. Change in phenotype without change in genotype

A

Epi-genetics

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4
Q

Epigenetic change is a ___ and ____ occurrence but epigenetic change is influenced by factors like age, environment, and disease state

A

Regular and natural

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5
Q

Normal functions of epigenetics include:

A

Cell differentiation, maintenance of genome structure, suppression of repetitive elements in invasive DNA, dosage compensation between XY and XX, and genomic imprinting

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6
Q

______ is a set chemical modifications to DNA and DNA associated proteins which alter gene expression and are heritable via meiosis and mitosis.

A

Epi-genome

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7
Q

DNA methylation and histone modification are common ____ of Epigenetics

A

Mechanisms

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8
Q

Euchromatin is associated with ____ DNA versus heterochromatin is associated with _____ DNA

A

Unmethylated
Methylated

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9
Q

The DNA _____ state is inherited

A

Methylation

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10
Q

_____ at histones promotes Euchromatin

_____ at histones promotes heterochromatin

A

Acetylation
Phosphorylation

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11
Q

When a methyl group is added to a ____ in DNA, this promotes heterochromatin and gene silencing

A

Cytosine

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12
Q

_____ ____ are CpG sequences 200 to 1000 base pairs.

_____ CpG islands are in/near promoters of active genes 60 to 70% of promoters have CPG islands.

_____ CpG islands are within large repetitive sequences and in intergenic regions they are next to genes that are silenced in a specific tissue

A

CpG islands
Unmethylated
Methylated

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13
Q

Cytosines are methylated by ___ ____ at the five carbon. _____ is a type of DNA methyl transferees that maintains existing methylation patterns following DNA replication. _____ and ____ target previously unmethylated CpGs they are highly expressed in the embryo during implantation and establish new methylation patterns

A

DNA methyltransferases
DNMT1
DNMT3A and DNMT3B

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14
Q

CpG represents a _____ DNA sequence when it is double stranded making it easy for it to be recognized and inherited

A

Palindromic

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15
Q

_____ _____ is when new DNA strands are not methylated during DNA replication, the methylated DNA gets diluted out as the cell or embryo goes through multiple cell divisions

A

Passive demethylation

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16
Q

____ ____ is by so-called TET (ten-eleven translocation) enzymes

A

Active demethylation

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17
Q
A
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18
Q

____ is a process by which some genes are epigenetically silenced during game to genesis in a parent of origin specific manner, which results in only one ____ being expressed for the imprinted loci

A

Imprinting
Allele

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19
Q

The main mechanism of epigenetic imprinting is ____ ____

A

CpG methylation

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20
Q

The fertilized ovum is ____ meaning it has the potential to become an entire organism and to make the placenta tissue

A

Totipotent

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21
Q

Epigenetic modifications during development determines ___ ____ and feet by limiting the developmental potential of individual cells and their progeny

A

Cell differentiation

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22
Q

The zygote must have many prior epigenetic marks ____ because both the eggs and Sperm had genomes of specialized cells: ____ and ___
Now we have to be able to make all cell types

A

Erased
Spermatozoa and oocytes

23
Q

Zygote genome has both male and female imprinted marks from paternal and maternal chromosomes, marks need to be erased so that ____ ___ of gametes based on its own genotypes can be expressed. It also needs to be _____ silent

A

Sexual determination
Transposons

24
Q

Epigenetic reprogramming occurs at two different points during development:
1. In the ____ before the blastocyst stage
2. In the ____ ___ ____ within the developing embryo

A

Zygote
Primordial germ cells (PGCs)

25
Q

In the zygote, the maternal and paternal genomes undergo ___ ____ resetting the genome for totipotency (ability to make all cell types) at the ____ stage.

A

Global demethylation
Blastocyst

26
Q

There is another round of global demethylation during migration of the ____ ____ ___. It’s thought that most imprinted alleles are not erased so that there are parent specific ____ patterns

A

Primordial germ cells
Methylation

27
Q

Need to be able to equalize the gene expression in individuals with 2X compared to those with one X. Change the gene _____ by _______. The X gets condensed down into a ____ ____. This is called _____

A

Regulation
X inactivation
Barr body
Lyonization

28
Q

X inactivation is initiated by a ___ _____ ___ called Xist. Xist is transcribed from the __ ______ ____ of the chromosome to be silenced. Xist coats Xi and serves as a scaffold for modifying enzymes.

A

Long non-coding RNA (lncRNA)
X inactivation center (XIC)

29
Q

Xi displays _____ histone modifications and DNA methylation

Xa displays _____ modifications

Somehow, XIC senses the number of X chromosomes and ____ silenced one

A

Repressive
Activating
Randomly

30
Q

_____: heritable change in gene activity not associated with a DNA sequence change. Results from _____ changes, or defects in epigenetic control mechanisms that cause deregulation

A

Epimutation
aberrant

31
Q

Epimutations affect many aspects of human health including ____ and ___ health

A

Metabolism
Mental

32
Q

Epimutations can drive carcinogenesis, 20% of sporadic breast cancers display ____ of the BRCA1 promoter

A

Hypermethylation

33
Q

Epigenetic deregulation on a molecular level:

A
34
Q

Epigenetic inheritance:
Week 3 of gestation, primordial germ cells are already forming, thus the babies future gametes can be _____ exposed to an epigenetic event

A

Directly

35
Q

_____ _____: transmission of an induced trait from one generation to another without direct exposure

A

Transgenerational inheritance

36
Q

______ _____= prenatal exposure: the mom (F0) is exposed while she is pregnant. The child’s (F1) somatic cell epigenome is programmed by the exposure but not it’s germline. The grandchild (F2) are unaffected. Direct exposure of the F1 child

A

Intergenerational inheritance

37
Q

_______ _____: the child (F1) is exposed during gestation and so are the child’s developing germ cells (F2). The grandchild (F2) will have a phenotype but does not pass it to his/her own children (F3) because those gametes are reprogrammed back to normal during development. Direct exposure of the F2 child

A

Multigenerational inheritance

38
Q

______ _____: the F1 gametes are modified during gestation so the F2 child is affected. If these marks are not erased during PGC differentiation, F2 gametes remain affected and the F3 generation has the altered phenotype. Indirect exposure

A

Transgenerational inheritance

39
Q

The evolution of metabolic epigenetic marking is thought to enhance ____ ____ by programming energy balance so that available nutrients are used most efficiently

A

Offspring survival

40
Q

Metabolic epigenetic marking allows for quicker adaptation to the environment than ____

A

Evolution

41
Q

Metabolic epigenetic marking is the programming of an offspring’s future metabolic responses by a stimulus that occurs during ____ ____ ____

A

Critical embryological periods

42
Q

Example of metabolic epigenetics is maternal diet of mice can affect the ____ of the offspring. It takes 3 generations of a normal maternal diet to reverse these changes

A

Length

43
Q

Women who were pregnant in the Dutch hunger winter famine only ate 400 to 800 calories per day and delivered low ___ ____ babies. By 50, those offspring had increase BMI, schizophrenia, diabetes. Likely caused by the _____ of the ____ locus compared to their same sex siblings

A

Birth weight
Hypomethylation
IGF2

44
Q

Both ____ and _____ of the mother can lead to obese phenotypes

A

Overnutrition and undernutrition

45
Q

____ ____ ____ is associated with insulin resistance in young adults

A

Prenatal psychosocial stress

46
Q

____ ____ ____ is associated with offspring having several metabolic syndrome conditions

A

Maternal holocaust exposure

47
Q

____ ____ during the preconception or prenatal period: offspring at increase risk for developing type II diabetes

A

Maternal bereavement

48
Q

Hypermethylation of tumor suppressor genes can cause ____. Global genomic ____ where all genes are expressed can lead to cancer. Persistence of ___ ___ inappropriately can lead to cancer

A

Cancer
Hypomethylation
m5c Residues

49
Q

Cancer:
____ increase and methylate CpG islands in tumor suppressor genes. It is proposed that ____ decrease and repetitive elements and oncogenes become demethylated

A

DNMTs
DNMTs

50
Q

Many ________ and _____ syndromes are caused by altered or defective function of epigenetic machinery: ability to read, write, erase, and remodel markings. Misregulation of ___ and ____ ____ are common features of disorders

A

Neurodevelopment
Developmental
Growth
Intellectual disability

51
Q

Imprinting disorders:
Beckwith wiedemann syndrome is an ___ disorder, only paternal imprinting present

Silver Russell syndrome is an ___ disorder only maternal imprinting present

A

Overgrowth
Undergrowth

52
Q

Imprinting disorders:
Prader Willi Syndrome is characterized by ___, ____, and ____. Only maternal imprinting present.
Angela syndrome is characterized by seizures ataxia speech impairment. Only ____ imprinting present

A

Hypotonia, hyperphagia, hypogonadism
Paternal

53
Q

Take home message

A

Fundamentals of Medicine: Exam II (19 decks)

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