module 7 lec 14 Flashcards
What is alternative splicing?
Alternative splicing is a process where different mRNA forms are produced from a single gene by splicing together various combinations of exons, leading to multiple protein variants.
How do small RNAs regulate gene expression?
Small RNAs can regulate mRNA stability and influence translation by interacting with mRNA, causing degradation or blocking translation.
How does post-transcriptional regulation occur at the protein level?
At the protein level, regulation can occur through mechanisms like protein degradation, phosphorylation, or folding, which affect the activity and function of the protein.
What are microRNAs (miRNA) and their role in gene regulation?
miRNAs are small RNAs that attach to mRNA and prevent translation, leading to downregulation of gene expression.
What are short interfering RNAs (siRNA) and their function?
siRNAs bind to mRNA and target double-stranded RNA (dsRNA) for destruction, silencing gene expression.
What are Piwi-interacting RNAs (piRNAs)?
piRNAs are small RNAs that interact with Piwi proteins and are involved in silencing transposons and other genomic elements in germ cells.
How important are miRNAs and siRNAs in gene regulation?
They are involved in regulating at least 70% of protein-coding genes and are highly conserved across the tree of life.
What is the processing of miRNA and siRNA precursors?
The primary transcript is much longer and is processed with a 5’ cap and poly A tail to form mature miRNA/siRNA.
Where are miRNAs and siRNAs encoded in the genome?
They are often coded in the genomes and can be found in introns of protein-coding genes.
What are miRNAs and siRNAs?
miRNAs and siRNAs are short RNA molecules (~20 bases) that regulate gene expression by binding to mRNA and either blocking translation or promoting degradation.
What does the enzyme Drosha do in miRNA processing?
Drosha crops the short stem-loop structure from the primary miRNA (pri-miRNA), initiating miRNA processinng
What is the role of the enzyme Dicer?
Dicer trims the ends of the miRNA precursor and removes the loop, helping to produce the mature miRNA.
What is the function of RISC (RNA-induced silencing complex)?
RISC degrades one strand of the miRNA duplex, producing the mature miRNA that can guide gene silencing.
What determines whether miRNA causes cleavage or translational repression?
The degree of complementarity between miRNA and the target mRNA.
Perfect complementarity leads to cleavage of the mRNA.
Imperfect complementarity results in translational repression.
What is RNA interference (RNAi)?
A mechanism that uses small RNAs (miRNA, siRNA) to regulate gene expression by degrading mRNA or blocking translation.
