mRNA Flashcards
What are structural genes?
Structural genes are genes that encode proteins and are initially transcribed into RNA to be converted into proteins.
Which enzymes transcribe DNA into RNA, and what types of RNA do they produce?
RNA polymerase II transcribes mRNA, RNA polymerase I transcribes rRNA, and RNA polymerase III transcribes tRNA.
What is a promoter, and what are two common types of promoter sequences?
A promoter is a DNA sequence upstream of a gene’s start site that initiates transcription. Common promoter sequences are the TATA box and GC box.
What role do transcription factors play in gene expression?
Transcription factors recognize promoter regions, help RNA polymerase bind to DNA, and initiate transcription.
What is the transcription bubble, and what happens within it?
The transcription bubble is an unwound region of DNA about 17 base pairs long, where RNA polymerase synthesizes RNA from the DNA template.
How does RNA polymerase know where to start transcribing a gene?
The DNA promoter sequence guides RNA polymerase to the correct start site for transcription.
What are upstream control elements, and what are enhancers?
Upstream control elements are DNA regions that regulate transcription initiation. Enhancers are distant DNA sequences that interact with promoters through DNA looping to enhance transcription.
What are exons and introns in a eukaryotic gene?
Exons are coding sequences that form the protein structure, while introns are non-coding sequences between exons.
What is splicing, and what complex performs it?
Splicing removes introns and joins exons in pre-mRNA. It is performed by the spliceosome, which includes small nuclear RNAs (snRNAs) and associated proteins.
When does mRNA capping occur, and why is it important?
Capping occurs immediately after transcription initiation, helping to protect the mRNA and facilitate ribosome binding.
What is polyadenylation, and where does it occur on mRNA?
Polyadenylation adds a poly(A) tail to the 3’ end of mRNA, helping stabilize the mRNA for translation.
What is alternative splicing, and why is it important?
lternative splicing is the process by which different combinations of exons are joined together to produce multiple mRNA variants from a single gene. It is important because it allows for increased protein diversity and enables cells to adapt to different functional requirements.
What are the mechanisms of gene regulation at the transcriptional level?
Transcription Factors: Proteins that enhance or repress the transcription of specific genes.
Enhancers and Silencers: Regulatory DNA sequences that can increase or decrease transcription when bound by specific proteins.
Chromatin Remodeling: Changes in chromatin structure that affect access to DNA, influencing transcription.
What is the role of RNA polymerase II in eukaryotic transcription?
RNA polymerase II is responsible for synthesizing mRNA and some snRNA and siRNA. It plays a critical role in transcribing protein-coding genes and requires several transcription factors for proper initiation.
How does post-transcriptional regulation affect gene expression?
RNA Editing: Altering nucleotide sequences of mRNA.
RNA Interference (RNAi): Small RNAs (like
siRNA and miRNA) can bind to mRNA and inhibit translation or promote degradation.
Stability and Transport: Regulation of mRNA stability and transport to the ribosome affects how much protein is produced.
