lecture 4 - epigenetics Flashcards
What is epigenetics?
Changes in gene expression without altering the DNA sequence.
What does epigenetics control in cells?
It regulates differentiation by tightly controlling gene expression.
What is an analogy for epigenetics?
The DNA sequence is like a musical score, genes are the notes, and epigenetic regulators are the conductor and musicians controlling how the music is played.
What are the two main types of chromatin?
Euchromatin: Loosely packed, transcriptionally active.
Heterochromatin: Tightly packed, transcriptionally inactive.
What are constitutive and facultative heterochromatin?
Constitutive heterochromatin: Always tightly packed and inactive.
Facultative heterochromatin: Can switch between active and inactive states.
How does chromatin structure affect mutation rates?
Closed chromatin regions have more germline and somatic mutations.
Open chromatin regions have higher insertion/deletion rates.
What are the three main types of epigenetic modifications?
DNA methylation – Adds methyl groups to DNA, usually silencing genes.
Histone modification – Alters chromatin structure to regulate gene access.
Micro-RNA (miRNA) – Small RNAs that regulate gene expression post-transcriptionally.
How does histone modification affect gene expression?
Acetylation opens chromatin, making genes more accessible.
Deacetylation & methylation tighten chromatin, silencing genes.
What role does DNA methylation play in gene expression?
Methylation of promoter regions usually silences genes.
Demethylation allows gene expression.
How is epigenetics linked to schizophrenia?
Monozygotic twins have a 50% occurrence rate.
DNA methylation differences are observed in schizophrenia patients.
Overexpression of DNMT enzymes leads to hypermethylation of key genes.
How do microRNAs influence viral infections?
miRNAs regulate immune response pathways (NF-KB & IFN).
Example:
miR-17 helps virus replication in SARS.
miR-214 aids immune evasion in SARS.
What are some medical applications of epigenetics?
Diagnostics (identifying diseases early).
Biomarkers (measuring disease progression or response to treatment).
Precision medicine (targeted treatments based on epigenetic profiles).
How are epigenetic drugs used in medicine?
Target epigenetic modifications to treat diseases like cancer.
More precise and less toxic compared to traditional drugs.
