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Flashcards in Lecture 21 Deck (50):
1

How an embryo develops

Epigenesis

2

The study of genes and heredity

Genetics

3

"Heritable modification" that does not involve changes in DNA

Epigenetics

4

Thrifty Phenotype hypothesis

When environmental convictions are poor for the parent, they are likely also to be poor for the offspring

5

According to Thrifty Phenotype hypothesis, what would happen when a parent experiences food shortage?

Biochemical modifications allow pre-adaptation to produce offspring that are metabolically thrifty, eating as much as possible, minimizing energy expenditure, and hoarding/conserving calories

6

What could happen to these pre-adapted offspring if put in an environment where food is plentiful?

Obesity

7

3 molecular mechanisms that alter chromatin structure?

- DNA methylation
- Histone modification
- RNA molecules that affect chromatin structure and gene expression

8

Where are methyl groups added in DNA methylation?

Nucleotide bases

9

Most common methylated base?

Cytosine ---> 5-methylcytosine

10

Does Acetylation increase or decrease gene expression?

Mechanism?

- Acetylation
- Histones less attracted to DNA
- DNA unwinds
- Increased access to DNA by proteins of gene expression
- Increased gene expression

11

Does Metylation increase or decrease gene expression?

Mechanism?

- Methylation
- DNA more condensed
- Less access to DNA by proteins of gene expression
- Decreased gene expression

12

What is a common feature of Epigenetics lesions in human disease?

A. Epigenetic lesions cause expression of lethal alleles
B. Organism with epigenetic lesions not viable
C. Epigenetic lesions affect a cell's ability to change its phenotype
D. A and B
E. All of the above

C. Epigenetic lesions affect a cell's ability to change its phenotype

13

Defects in normal epigenetic apparatus in Rett syndrome results in?

Impeding of normal development

14

Many epigenetic lesions that could affect a pluripotent program is involved in:

Cancer

15

What involves the loss of normal plasticity of response to internal and external environmental signals?

Aging

16

What is the epigenome?

Record of chemical changes to DNA and histones of an organism that can be passed down to offspring

17

Function(s) of epigenome?

A. Modulate the effect of genetic variation
B. Modulate protein folding of gene product of variant locus or chromatin protein
C. Affect gene expression through action of chromatin proteins
D. Affect gene expression through DNA methylation
E. A, C, and D
F. All of the above

F. All of the above

Epigenome can modulate the effect of genetic variation by:
- Affecting gene expression through action of chromatin proteins and DNA methylation
- Modulating protein folding of gene product of variant locus or chromatin protein


18

What can affect the epigenome?

A. Environmental factors
B. Sequence variation in genes encoding chromatin/chaperones
C. Faulty DNA repair proteins
D. All of the above
E. A and B

E. A and B

19

Where does DNA methylation occur?

CpG residues/islands (Cytosine-phosphate-guanine)

20

How is DNA methylation stably maintained through DNA replication?

- DNA fully methylated at CpG dinucleotides
- DNA replication produces two new strands lacking methyl groups
- New strands are hemimetylated
- Methyl groups attract methyltransferases
- Methyl transferases add methyl groups to unmethylated strands
- Full methylated DNA

21

How do epigenetics affect queen/worker bees phenotypes?

- Royal jelly (queen bee food) causes silencing of a methyltranferase gene
- Changes in methylation patterns
- Changes in gene expression
- Results in queen bee phenotype

(No Royal jelly --> worker phenotype)

22

Types of Histone modifications include addition of:

Phosphates
Methyl groups
Acetylene groups
Ubiquitin

23

What is characterized as an interaction between two alleles that leads to a heritable change in expression of one of the alleles?

Paramutaton

23

What is responsible for inducing a paramutation in an allele?

A. siRNA
B. miRNA
C. mRNA
D. A and B

A. siRNA

24

Which is more effective at inducing Epigenetic changes?

A. siRNA
B. Nonspecific miRNA
C. miRNA
D. Specific miRNA
E. All of the above

D. Specific miRNA

25

Which of the following would cause mRNA degredation that would cause a homozygote to develop the phenotype of a hetyerozygote?

A. siRNA
B. miRNA
C. mRNA
D. A and B

B. miRNA

26

Young rats exposed to more licking and grooming from their mothers develop different patterns of DNA methylation. This alters the expression of stress-response genes and makes them less fearful as adults. What is this phenomenon called?

A. Epigenetics
B. Behavioral genetics
C. Behavioral epigenetics
D. Maternal instinct hypothesis

B.

27

Which of the following are sources of behavioral epigenetics?

A. Maternal behavior
B. Early stress
C. Cognition
D. A and B
E. All of the above

E. All of the above

28

Which gene is responsible for X inactivation?

A. Xa
B. Xist
C. Inactivation factor X
D. A and B

B. Xist

29

What is responsible for inactivation of X chromosome?

A. Xist RNA coating chromosome
B. Recruitment of PCR2
C. Acetylation of promotors
D. Histone deacetylation
E. Methylation of promotors
F. A, B and C
G. All except B
H. All except C
I. All of the above

H. All except C

30

Which of the following encodes the RNA (IncRNA) responsible for coating the X chromosome during X inactivation?

A. Several genes
B. Xist gene only
C. Xist and Xa
D. Non of the above

A. Several genes

31

What is the name of the randomly inactivated, highly condensed chromosome that develops from X inactivation in mammalian females?

Barr body

32

How does X inactivation produce mosaics?

Some cells - active A allele; inactive B allele
Other cells - inactive A allele; active B allele

Creates patches - cells in one area have different phenotype than another area bc of random inactivation of X chromosomes

33

Which phenomenon would explain why an individual would not express a mutant allele inherited from their mother but would express the mutant phenotype if allele was inherited from the father?

A. Epigenetics
B. X inactivation
C. Environmental epigenetics
E. Genomic imprinting

E. Genomic imprinting

34

Genomic imprinting definition

Epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner

35

Which phenomenon explains the inheritance of 2 copies of a chromosome from one parent?

A. Genomic imprinting
B. Nondisjunction
C. Uniparental disomy
D. A and B
E. B and C

E. B and C

36

Nondisjunction resulting in an extra chromosome can result in which of the following?

A. Miscarriage
B. Uniparental disomy
C. Trisomy
D. All of the above

D. All of the above

37

What is most likely to occur if an egg's extra chromosome received from Nondisjunction is not eliminated quickly?

Miscarriage


(Down's syndrome only occurs if trisomy of chromosome 21, trisomies of all otherwise chromosomes will likely results in miscarriage.)

38

What is a possible hypothesis explaining why some regions of the human genome differentials imprinted resulting in differing numbers of differentials methylated regions (DMRs) in males and females?

Different evolutionary pressures on male vs female reproductive strategies

Males - many sperm
Females - one egg

39

Significance of early life in epigenomic programming in chronic metabolic and degenerative disorders.

Non-optimal epigenomic programming early in life initiates or influences these disorders.

Conception to early infancy is often called the most important period of her life.

40

Pathways that are altered by epigenetic programming can result in:

A. Dysregulation of important physiological functions
B. Metabolic syndrome
C. Diabetes
D. A, B, and C
E. B and C

D. A, B, and C

41

Do newborns of obese parents have suceptibility for epigenetic changes? If so, what kind?

Altered DNA methylation patterns at imprinted genes

42

Effects of lead exposure

Can alter DNA methylation

Lowest exposure seen to have largest increase in DNA methylation

43

Effects of CpG island methylation phenotype (CIMP)

CIMP in promotors of tumor-suppressor genes

CIMP can physically inhibit binding of transcription factors, thus silencing the gene

CIMP in promotor regions of tumor-suppressor genes would silences expression of tumor suppressor genes and cause uncontrolled cell proliferation

44

What is characterized as the overall pattern of chromatin modifications possessed by each individual organism?

Epigenome

45

Which of the methods (letter) are the ways to detect the following:

1. DNA methylation
2. Histone modifications

A. Restriction endonucleases
B. bisulfate sequencing
C. ChIP

1. A. Restriction endonucleases; B. bisulfate sequencing
2. C. ChIP

46

Which method converts unmethylated cytosine residues to uracil, but leaves 5-methyl cytosine residues unaffected in order to detect these methylated cytosines?

A. ChIP
B. Restriction endonucleases
C. Bisulfate sequencing
D. Histone acetylation



C. Bisulfate sequencing

47

Which of the following methods is used to precipitate methylated DNA using Abs to identify the binding sites of DNA-associated proteins?

A. ChIP
B. Restriction endonucleases
C. Bisulfate sequencing

A. ChIP

48

Which of the following can be attributed to some form of epigenetics?

A. Obesity
B. Regulation of oncogenesis
C. Medulloblastoma
D. All of the above

D. All of the above

49

Explain the obesity "on/off switch" and how epigenetics is involved.

Obesity "on switch" is characterized by reduced expression of an imprinted gene network

Obesity on = obesity gene expressed; skinny gene inactivated
Obesity off = skinny gene expressed; obesity gene inactivated