Podcast
Questions and Answers
What is the primary function of alternative splicing in gene expression?
What is the primary function of alternative splicing in gene expression?
- Decreasing the stability of mRNA across all tissues
- Producing different mature mRNA and subsequent proteins (correct)
- Regulating the binding of RNA polymerase to DNA
- Enhancing the transcription rate of genes
How does alternative polyadenylation affect mRNA?
How does alternative polyadenylation affect mRNA?
- It can suppress translation and affect mRNA stability (correct)
- It exclusively enhances gene expression in all cases
- It leads to the production of identical mRNA molecules
- It only increases the size of mRNA transcripts
Which element is specifically involved in transcriptional activation in eukaryotes?
Which element is specifically involved in transcriptional activation in eukaryotes?
- Upstream activation sequence (UAS) (correct)
- Introns only
- Repressor proteins
- Spliceosome components
What is a consequence of using different poly(A) sites in pre-mRNA?
What is a consequence of using different poly(A) sites in pre-mRNA?
What does the C-terminal domain (CTD) of RNA Polymerase II primarily regulate?
What does the C-terminal domain (CTD) of RNA Polymerase II primarily regulate?
What is a primary role of histones in chromatin structure?
What is a primary role of histones in chromatin structure?
Which histone modification is associated with gene activation?
Which histone modification is associated with gene activation?
How does DNA methylation generally affect gene expression?
How does DNA methylation generally affect gene expression?
What are HATs responsible for in the context of histone modification?
What are HATs responsible for in the context of histone modification?
What is the consequence of methylation at CpG islands?
What is the consequence of methylation at CpG islands?
Which histone modification typically indicates gene silencing?
Which histone modification typically indicates gene silencing?
Which statement about histone modifications is correct?
Which statement about histone modifications is correct?
What type of chromatin is typically associated with high levels of DNA methylation?
What type of chromatin is typically associated with high levels of DNA methylation?
What is the primary function of long non-coding RNA (lncRNA)?
What is the primary function of long non-coding RNA (lncRNA)?
Which of the following statements about RISC (RNA-induced silencing complex) is true?
Which of the following statements about RISC (RNA-induced silencing complex) is true?
What mechanism primarily determines the stability of a protein?
What mechanism primarily determines the stability of a protein?
Which of the following accurately describes the result of protein phosphorylation?
Which of the following accurately describes the result of protein phosphorylation?
Which of the following best describes the origin of RNAi?
Which of the following best describes the origin of RNAi?
What is the primary function of Cyclin D1 in the context of the cell cycle?
What is the primary function of Cyclin D1 in the context of the cell cycle?
Which of the following factors does NOT influence mRNA turnover?
Which of the following factors does NOT influence mRNA turnover?
What is the mechanism by which RNA interference regulates gene expression?
What is the mechanism by which RNA interference regulates gene expression?
Which type of decay pathway does NOT rely on poly(A) degradation?
Which type of decay pathway does NOT rely on poly(A) degradation?
Which of the following best describes the stability time span of mRNA?
Which of the following best describes the stability time span of mRNA?
What role does methyltransferase enzyme play in DNA replication?
What role does methyltransferase enzyme play in DNA replication?
What effect does cigarette smoke have on epigenetic changes?
What effect does cigarette smoke have on epigenetic changes?
What is genomic imprinting primarily responsible for?
What is genomic imprinting primarily responsible for?
How does folate deficiency during development affect health?
How does folate deficiency during development affect health?
In Prader-Willi Syndrome, what is expressed when there is a deletion in the paternal chromosome?
In Prader-Willi Syndrome, what is expressed when there is a deletion in the paternal chromosome?
What is a common symptom observed in Angelman Syndrome?
What is a common symptom observed in Angelman Syndrome?
Which of the following is NOT a feature of Prader-Willi Syndrome?
Which of the following is NOT a feature of Prader-Willi Syndrome?
What is the key process that links maternal behavior to transgenerational effects in epigenetics?
What is the key process that links maternal behavior to transgenerational effects in epigenetics?
What typically induces gene silencing in genomic imprinting?
What typically induces gene silencing in genomic imprinting?
Which of the following effects can result from early life experiences on behavior?
Which of the following effects can result from early life experiences on behavior?
Study Notes
Epigenetic Regulation
- Changes in chromatin structure and DNA methylation significantly affect gene expression.
- Chemical modifications of histone proteins (e.g., methylation, acetylation) alter transcriptional activity.
- RNA molecules play a role in modifying chromatin structure and influencing gene expression.
Chromatin and Histone Modifications
- Histones repress transcription generally; modifications can reverse this effect.
- Key modifications include:
- Histone methylation (activating marks: H3: K4, K36, K79; silencing marks: H3: K27, K9; H4: K20).
- Histone acetylation typically stimulates transcription, while deacetylation reduces it.
- Histone phosphorylation (notably at H3S10) and ubiquitylation impact gene regulation.
- Methylated DNA, particularly within CpG islands, is often transcriptionally inactive.
Maintenance of DNA Methylation
- Methylation patterns are preserved through DNA replication.
- Methyltransferase enzymes ensure methylation is passed to daughter strands.
- Methylcytosines attract repressor proteins, contributing to gene silencing.
Environmental Effects on Epigenetics
- Behavioral epigenetics highlights how early life experiences can have lasting effects on behavior.
- Nutritional deficiencies and environmental exposures, like folate deficiency and cigarette smoke, can induce epigenetic changes linked to health risks.
Genomic Imprinting
- Imprinting results in differential expression of maternal and paternal alleles for dosage compensation.
- Key to the development of certain diseases and conditions, including Prader-Willi and Angelman syndromes.
- The Prader-Willi Syndrome is characterized by paternal chromosome mutations leading to only maternal genes expressing, while Angelman Syndrome arises from mutations in the maternal allele.
RNA Processing and Expression Control
- Alternative splicing allows different intron-exon configurations leading to various proteins from the same gene.
- Alternative polyadenylation affects mRNA stability and translation efficiency, increasing diversity in gene expression.
- RNA stability is regulated by degradation control, with cis-elements residing in the 3’-UTR influencing mRNA turnover.
RNA Interference (RNAi)
- RNAi is a post-transcriptional regulation mechanism involving small RNA molecules like siRNAs and miRNAs.
- It regulates gene expression through mRNA cleavage, translation inhibition, transcriptional silencing, and mRNA degradation.
- RNAi mechanisms were initially discovered as a defense against viruses.
Long Non-coding RNA (lncRNA)
- lncRNAs are transcribed from DNA but are not translated into proteins. They play various regulatory roles in chromatin function and mRNA stability.
- Functions of lncRNAs include modulation of chromatin states, interference in signaling pathways, and alteration of mRNA translation.
Translational and Protein Control
- Protein production is influenced by mRNA stability and degradation rates.
- Phosphorylation typically activates proteins, while dephosphorylation leads to inactivation.
- Factors like ubiquitin assist in protein degradation, affecting overall protein levels within the cell.
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Description
Test your understanding of epigenetic regulation, including changes in chromatin structure, DNA methylation patterns, and histone modifications. Explore how these molecular mechanisms influence gene expression and chromosome changes.