Lecture 6 - Epigenetic Gene Regulation

Question 1

A gene that is maternally imprinted is expressed only from the _________ allele.

Answer 1

paternal allele

Question 2

A gene that is paternally imprinted is expressed only from the _________ allele.

Answer 2

maternal allele

Question 3

DNA methylation results in _____ of gene expression.

Answer 3

repression

Question 4

What is defined as nonequivalence in expression of alleles between the paternal and maternal genomes at a certain gene loci?

Answer 4

Genomic imprinting

Question 5

_____________ refers to the inheritance of two copies of a full chromosome, or its portions, from a single parent.

Answer 5

uniparental disomy

Question 6

_______ recognize CpG sequences and methylate certain C residues in this sequence.

Answer 6

Cytosine methyltransferases (such as Dnmt 1, Dnmt3a, Dnmt3b)

Question 7

Dnmt1 methyltransferase carries out the perpetuation of ___________ which stably transmits the CpG methylation pattern to daughter cells.

Answer 7

maintenance methylation

Question 8

De novo methylation is responsible for:

Answer 8

metylating genomes in sperm and egg cells

Question 9

The Dnmt1 gene is highly expressed in what 3 types of (developmental) cells?

Answer 9

1. Male germ cells
2. Mature oocytes
3. Early embryo

Question 10

What type of promoters does the Dnmt1 methyl transferase gene utilize?

Answer 10

oocyte and spermatocyte-specific promoters

Question 11

The activity of DNA methyltransferases is regulated by post-translational modifications, including these 5:

Answer 11

1. phosphorylation
2. acetylation
3. methylation
4. sumoylation
5. ubiquitination

Question 12

Where does genetic imprinting occur during the formation of the eggs and sperm?

Answer 12

the ovary (eggs) and testes (sperm)

Question 13

After genes are switched off in the eggs (when imprinted and passed from mother) and sperm (when passed from father), the imprinting is erased. When is it re-established again?

Answer 13

In the next generation when each person produces his or her own eggs or sperm.

Question 14

Addition of the acetyl group to lysines - by histone acetyl transferases (HATs) - generates what?

Answer 14

Open and transcriptionally active chromatin

Question 15

Methylated CpG binding proteins (MECP) act as ____________ partly by recruiting histone deacetylases (HDACs) to remove acetyl groups from histones.

Answer 15

transcriptional repressors

Question 16

What are the 2 major results of removing acetyl groups from histones?

Answer 16

1. Chromatin condensation

2. Inhibition of gene expression

Question 17

What is the term for histone modifications that can influence gene expression independent of the DNA sequence?

Answer 17

histone code

Question 18

What are HDAC inhibitors?

Answer 18

A new class of anticancer agents that promote growth arrest, differentiation, and apoptosis of tumor cells.

Question 19

70% of PWS cases are due to a deletion in the 15q11-q13 region of what chromosome?

Answer 19

the paternal chromosome

Question 20

30% of PWS cases are due to __________ of chromosome 15 from the mother.

Answer 20

uniparental disomy

Question 21

70% of Angelman Syndrome cases are due to a deletion in the 15q11-q13 region of what chromosome?

Answer 21

the maternal chromosome

*Note: 5% of AS cases are due to mutations in the disomy of chromosome 15 from the father.

Question 22

Histone acetyl transferases (HATs):

A. Add acetyl groups to CpG dinucleotides
B. Remove acetyl groups from CpG dinucleotides
C. Add acetyl groups to histones
D. Result in repression of gene expression

Answer 22

C. The generates an open, transcriptionally active chromatin.