[07] Basics of Epigenetics Flashcards
What is Epigenetics?
The study of changes in organisms caused by the modification of gene expression, not alteration of the genetic code itself.
What are Epigenetic marks?
Chemical modifications to DNA and proteins that can change the activity of a DNA segment without changing the sequence.
How do Epigenetic changes affect an organism?
They can change an organism’s physical characteristics, disease susceptibility, and behavior.
What’s the difference between Genetics and Epigenetics?
Genetics involves changes in the DNA sequence, while Epigenetics involves changes in the way genes are expressed.
What are the two main types of epigenetic marks?
- DNA methylation
- Histone modification
What does DNA methylation do?
It typically acts to repress gene transcription.
What is Histone modification?
A covalent post-translational modification to histone proteins which can alter gene expression.
What is a major effect of Histone acetylation?
It usually results in gene activation.
How are epigenetic changes inherited?
They can be passed on from cell to cell as cells divide, and from one generation to the next.
How do lifestyle and environment influence Epigenetics?
Factors like diet, stress, physical activity, and toxins can cause epigenetic changes.
What is the role of Epigenetics in cancer?
Abnormal placement or timing of epigenetic marks can lead to uncontrolled cell growth and cancer.
What are CpG islands?
They are regions of DNA where a cytosine nucleotide is followed by a guanine nucleotide and are often associated with gene promoters.
What happens when a CpG island in a promoter region is heavily methylated?
The associated gene is often inactive.
What is an Epigenome?
The overall pattern of chromatin modifications present in a particular cell.
Are epigenetic changes reversible?
Yes, unlike genetic changes, epigenetic changes are reversible.
What is Epigenetic therapy?
It’s a type of therapy that aims to reverse abnormal gene silencing or activation.
Give an example of Epigenetic therapy.
Drugs that inhibit DNA methyltransferases in cancer treatment.
What is “genomic imprinting”?
It’s a type of epigenetic modification where certain genes are expressed in a parent-of-origin-specific manner.
Give an example of a disease associated with aberrant genomic imprinting.
Prader-Willi syndrome.
What is X-chromosome inactivation?
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.
What is Histone Acetylation?
The addition of an acetyl group to a histone protein, often resulting in gene activation.
What role does Histone Acetylation play in gene expression?
It relaxes the DNA and makes the genes more accessible for transcription.
What are Histone Acetyltransferases (HATs)?
They are enzymes that add acetyl groups to histones.
Define “Histone Acetyltransferases” (HATs).
Enzymes that acetylate conserved lysine amino acids on histone proteins by transferring an acetyl group from acetyl CoA to form ε-N-acetyl lysine.
What are Histone Deacetylases (HDACs)?
They are enzymes that remove acetyl groups from histones.
Define “Histone Deacetylases” (HDACs).
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.
How does Histone Acetylation affect the chromatin structure?
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.
Can Histone Acetylation be passed onto daughter cells?
Yes, Histone Acetylation marks can be inherited through cell division, albeit less stable than DNA methylation marks.
How does Histone Acetylation contribute to long-term memory?
Histone Acetylation plays a key role in the regulation of genes related to memory formation and storage.
What happens when Histone Acetylation is dysregulated?
Dysregulated Histone Acetylation patterns can lead to abnormal gene activity and diseases, including cancer.
