Gene Expression Regulation

Study Notes

Gene Expression Regulation

Epigenetic Modification

Refers to heritable changes in gene function that occur without a change in the underlying DNA sequence
Involves the addition of chemical groups to DNA or histone proteins
Types of epigenetic modifications:
- DNA methylation: addition of a methyl group to cytosine residues in CpG islands
- Histone modification: addition of acetyl, methyl, or phosphate groups to histone proteins
- Chromatin remodeling: alteration of chromatin structure to allow or deny access to transcription factors
Epigenetic modifications can:
- Activate or repress gene transcription
- Influence chromatin structure and accessibility
- Play a role in development, cell differentiation, and disease

Transcriptional Regulation

Regulation of gene expression at the level of transcription initiation
Involves the binding of transcription factors to specific DNA sequences
Transcription factors can:
- Activate transcription by binding to enhancers or promoters
- Repress transcription by binding to silencers or promoters
Types of transcriptional regulation:
- Positive regulation: activation of transcription
- Negative regulation: repression of transcription
- Induction: increased transcription in response to a signal
- Repression: decreased transcription in response to a signal

Post-transcriptional Regulation

Regulation of gene expression after transcription has occurred
Involves the processing, localization, and translation of mRNA
Mechanisms of post-transcriptional regulation:
- mRNA splicing: removal of introns and joining of exons
- mRNA localization: targeting of mRNA to specific cellular locations
- mRNA stability: regulation of mRNA degradation rates
- Translation initiation: regulation of protein synthesis initiation
- MicroRNA-mediated regulation (see below)

MicroRNA Regulation

Small non-coding RNAs that regulate gene expression by binding to mRNA
Mechanism:
- MicroRNAs bind to complementary mRNA sequences
- Blocking translation or inducing degradation of target mRNAs
MicroRNA function:
- Regulation of gene expression in response to environmental cues
- Regulation of cellular processes, such as cell growth and differentiation

Gene Silencing

Permanent inactivation of a gene or gene product
Mechanisms of gene silencing:
- Epigenetic modification: heritable changes to chromatin structure or DNA methylation
- RNA interference (RNAi): degradation of specific mRNAs by small RNAs
- Gene knockout: targeted disruption of a gene sequence
Gene silencing can be used to:
- Study gene function
- Treat genetic diseases
- Develop novel therapies

Description

This quiz covers the mechanisms of gene expression regulation, including epigenetic modification, transcriptional regulation, post-transcriptional regulation, and gene silencing. It explores the different types of regulation and their roles in cell development, differentiation, and disease.