[07] Basics of Epigenetics

Question 1

What is Epigenetics?

Answer 1

The study of changes in organisms caused by the modification of gene expression, not alteration of the genetic code itself.

Question 2

What are Epigenetic marks?

Answer 2

Chemical modifications to DNA and proteins that can change the activity of a DNA segment without changing the sequence.

Question 3

How do Epigenetic changes affect an organism?

Answer 3

They can change an organism’s physical characteristics, disease susceptibility, and behavior.

Question 4

What’s the difference between Genetics and Epigenetics?

Answer 4

Genetics involves changes in the DNA sequence, while Epigenetics involves changes in the way genes are expressed.

Question 5

What are the two main types of epigenetic marks?

Answer 5

• DNA methylation
• Histone modification

Question 6

What does DNA methylation do?

Answer 6

It typically acts to repress gene transcription.

Question 7

What is Histone modification?

Answer 7

A covalent post-translational modification to histone proteins which can alter gene expression.

Question 8

What is a major effect of Histone acetylation?

Answer 8

It usually results in gene activation.

Question 9

How are epigenetic changes inherited?

Answer 9

They can be passed on from cell to cell as cells divide, and from one generation to the next.

Question 10

How do lifestyle and environment influence Epigenetics?

Answer 10

Factors like diet, stress, physical activity, and toxins can cause epigenetic changes.

Question 11

What is the role of Epigenetics in cancer?

Answer 11

Abnormal placement or timing of epigenetic marks can lead to uncontrolled cell growth and cancer.

Question 12

What are CpG islands?

Answer 12

They are regions of DNA where a cytosine nucleotide is followed by a guanine nucleotide and are often associated with gene promoters.

Question 13

What happens when a CpG island in a promoter region is heavily methylated?

Answer 13

The associated gene is often inactive.

Question 14

What is an Epigenome?

Answer 14

The overall pattern of chromatin modifications present in a particular cell.

Question 15

Are epigenetic changes reversible?

Answer 15

Yes, unlike genetic changes, epigenetic changes are reversible.

Question 16

What is Epigenetic therapy?

Answer 16

It’s a type of therapy that aims to reverse abnormal gene silencing or activation.

Question 17

Give an example of Epigenetic therapy.

Answer 17

Drugs that inhibit DNA methyltransferases in cancer treatment.

Question 18

What is “genomic imprinting”?

Answer 18

It’s a type of epigenetic modification where certain genes are expressed in a parent-of-origin-specific manner.

Question 19

Give an example of a disease associated with aberrant genomic imprinting.

Answer 19

Prader-Willi syndrome.

Question 20

What is X-chromosome inactivation?

Answer 20

It’s an epigenetic process that silences one of the two X chromosomes in female mammals to prevent them from having twice as many X chromosome gene products as males.

Question 21

What is Histone Acetylation?

Answer 21

The addition of an acetyl group to a histone protein, often resulting in gene activation.

Question 22

What role does Histone Acetylation play in gene expression?

Answer 22

It relaxes the DNA and makes the genes more accessible for transcription.

Question 23

What are Histone Acetyltransferases (HATs)?

Answer 23

They are enzymes that add acetyl groups to histones.

Question 24

Define “Histone Acetyltransferases” (HATs).

Answer 24

Enzymes that acetylate conserved lysine amino acids on histone proteins by transferring an acetyl group from acetyl CoA to form ε-N-acetyl lysine.

Question 25

What are Histone Deacetylases (HDACs)?

Answer 25

They are enzymes that remove acetyl groups from histones.

Question 26

Define “Histone Deacetylases” (HDACs).

Answer 26

Enzymes that remove acetyl groups (O=C-CH3) from an ε-N-acetyl lysine amino acid on a histone, allowing the histones to wrap the DNA more tightly.

Question 27

How does Histone Acetylation affect the chromatin structure?

Answer 27

Acetylation neutralizes the positive charge on histones, thereby reducing the interaction of the N termini of histones with the negatively charged phosphate groups of DNA. As a result, the condensed chromatin is transformed into a more relaxed structure that is associated with greater levels of gene transcription.

Question 28

Can Histone Acetylation be passed onto daughter cells?

Answer 28

Yes, Histone Acetylation marks can be inherited through cell division, albeit less stable than DNA methylation marks.

Question 29

How does Histone Acetylation contribute to long-term memory?

Answer 29

Histone Acetylation plays a key role in the regulation of genes related to memory formation and storage.

Question 30

What happens when Histone Acetylation is dysregulated?

Answer 30

Dysregulated Histone Acetylation patterns can lead to abnormal gene activity and diseases, including cancer.