Gene Expression & RNA Interference Flashcards
(16 cards)
What are transcription factors and what role do they play in gene expression?
Transcription factors (TFs) are proteins that bind to specific DNA sequences (promoters/enhancers) to regulate the initiation of transcription by RNA polymerase.
How do epigenetic modifications influence gene expression?
DNA methylation and histone modification can either condense or relax chromatin structure, affecting the accessibility of transcriptional machinery and gene expression levels.
What is a promoter and why is it essential for gene expression?
A promoter is a DNA sequence upstream of a gene that acts as a binding site for RNA polymerase and transcription factors, initiating mRNA synthesis.
What is alternative splicing and how does it affect gene expression?
Alternative splicing allows different mRNA isoforms to be produced from a single gene, resulting in multiple protein variants and increased proteomic diversity.
How does mRNA stability impact gene expression levels?
The more stable an mRNA molecule is, the longer it remains in the cytoplasm for translation, leading to more protein being synthesized.
What is the function of the 3’ untranslated region (3’ UTR) in mRNA?
The 3’ UTR contains sequences that regulate mRNA stability, localization, and translational efficiency, often interacting with microRNAs and RNA-binding proteins.
What is RNA interference (RNAi)?
RNAi is a cellular process where small RNAs (siRNA or miRNA) bind complementary mRNA sequences, leading to mRNA degradation or translational inhibition.
How do siRNAs differ from miRNAs?
siRNAs: Exogenous or synthetic, perfectly match target mRNA → degradation
miRNAs: Endogenous, imperfect match → translational repression or degradation
What is the role of Dicer and RISC in RNAi?
Dicer cleaves dsRNA into siRNA. RISC (RNA-induced silencing complex) uses one siRNA strand to guide it to complementary mRNA, which it then degrades or silences.
What is CRISPR-Cas13 and how does it differ from Cas9?
Cas13 targets RNA (not DNA) for cleavage, allowing transient and reversible gene expression modifications—ideal for diseases where DNA editing is risky.
What is the role of ADAR enzymes in RNA editing?
ADARs convert adenosine to inosine in RNA, which can alter codons and protein function post-transcriptionally.
What is gene overexpression and why is it used in biotechnology?
Overexpression involves increasing the transcription of a gene to produce high levels of a protein—useful for research, therapeutic production (e.g. insulin), or pathway manipulation.
How are plasmids used to overexpress genes in cells?
A gene of interest is cloned into a plasmid under a strong promoter and introduced into host cells (via transformation or transfection) to drive high-level expression.
What is a viral vector and how is it used for overexpression?
Viral vectors (e.g. lentivirus, AAV) deliver transgenes into host cells, achieving stable or transient overexpression for therapeutic or experimental purposes.
How is RNAi used in modern therapeutics?
RNAi-based drugs (e.g. patisiran) silence disease-causing genes and are being developed for conditions like hereditary ATTR amyloidosis and certain cancers.
How does gene expression modification support personalized medicine?
It allows selective upregulation or silencing of genes based on a patient’s genetic profile, enhancing treatment precision and efficacy.
