6 Questions
What is the function of the 5' untranslated region (5' UTR) in mRNA structure?
To provide a binding site for the ribosome
What is the role of GTP hydrolysis during translation initiation?
To provide energy for initiation complex formation
What is an example of post-transcriptional regulation of gene expression?
mRNA splicing
What is the consequence of codon degeneracy?
Multiple codons code for the same amino acid
What is the function of the peptidyl transferase center in the large subunit of the ribosome?
To form peptide bonds
What is the role of ribosome profiling in understanding translation regulation?
To measure the occupancy of ribosomes on mRNA
Study Notes
mRNA Structure
- Consists of:
- 5' untranslated region (5' UTR): non-coding region before the start codon
- Coding region: sequence of codons that encode the protein
- 3' untranslated region (3' UTR): non-coding region after the stop codon
- Poly-A tail: repeated adenine nucleotides at the 3' end
- mRNA is single-stranded and complementary to the template DNA strand
Translation Initiation
- Initiation complex formation:
- Ribosome binds to mRNA at the 5' UTR
- Initiator tRNA (Met-tRNAi) binds to the start codon (AUG)
- GTP hydrolysis provides energy for initiation
- Scanning model: ribosome scans mRNA from 5' to 3' to find the start codon
Protein Synthesis Regulation
- Transcriptional regulation:
- Regulation of gene expression through transcription factor binding
- Post-transcriptional regulation:
- mRNA splicing, editing, and degradation
- MicroRNA-mediated mRNA degradation
- Translational regulation:
- Regulation of initiation, elongation, and termination of translation
- Ribosome profiling and mRNA localization
Codon Usage
- Codon degeneracy: multiple codons code for the same amino acid
- Codon bias: non-random usage of synonymous codons in a genome
- Codon usage tables: statistical analysis of codon frequencies in a genome
- Codon optimization: engineering of codon usage for improved protein expression
Ribosome Function
- Ribosome structure:
- Large subunit (50S): peptidyl transferase center
- Small subunit (30S): mRNA binding site
- Ribosome cycle:
- Initiation: binding of mRNA and initiator tRNA
- Elongation: amino acid addition and peptide bond formation
- Termination: release of completed protein and recycling of ribosome
- Ribosome dynamics:
- Conformational changes during translation
- Ribosome profiling: analysis of ribosome occupancy on mRNA
Test your knowledge of mRNA structure, translation initiation, protein synthesis regulation, codon usage, and ribosome function. Learn about the different regions of mRNA, the scanning model, and the regulation of gene expression.
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