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Questions and Answers
What is the role of the 12 protein factors during translation initiation in eukaryotes?
What is the role of the 12 protein factors during translation initiation in eukaryotes?
During the elongation stage of translation, which site does the amino-acyl tRNA enter first?
During the elongation stage of translation, which site does the amino-acyl tRNA enter first?
What happens to the tRNA at the P site during the elongation process?
What happens to the tRNA at the P site during the elongation process?
Which of the following factors is responsible for facilitating the shift of tRNAs during the elongation stage in eukaryotes?
Which of the following factors is responsible for facilitating the shift of tRNAs during the elongation stage in eukaryotes?
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What occurs when a stop codon is reached during translation?
What occurs when a stop codon is reached during translation?
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Which of the following signals the termination of translation?
Which of the following signals the termination of translation?
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Which ribosomal subunit first joins the initiation complex in eukaryotic translation?
Which ribosomal subunit first joins the initiation complex in eukaryotic translation?
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In prokaryotes, what is the equivalent of eEF2 during the elongation process?
In prokaryotes, what is the equivalent of eEF2 during the elongation process?
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What role do aminoacyl tRNA synthetases have in the translation process?
What role do aminoacyl tRNA synthetases have in the translation process?
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What is the function of the Shine-Dalgarno sequence in prokaryotic translation?
What is the function of the Shine-Dalgarno sequence in prokaryotic translation?
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In eukaryotes, which component assists in binding mRNA to the ribosome during translation initiation?
In eukaryotes, which component assists in binding mRNA to the ribosome during translation initiation?
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Which factors are involved in the initiation phase of translation in eukaryotes?
Which factors are involved in the initiation phase of translation in eukaryotes?
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What is the composition of ribosomes?
What is the composition of ribosomes?
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Which of the following amino acids is involved in the initiation of translation in prokaryotes?
Which of the following amino acids is involved in the initiation of translation in prokaryotes?
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Which of the following is NOT a component required for translation initiation in eukaryotes?
Which of the following is NOT a component required for translation initiation in eukaryotes?
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What is the role of elongation factors during translation?
What is the role of elongation factors during translation?
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During translation termination in prokaryotes, which release factors are involved?
During translation termination in prokaryotes, which release factors are involved?
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What is the main function of the 30S ribosomal subunit in prokaryotic translation?
What is the main function of the 30S ribosomal subunit in prokaryotic translation?
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Study Notes
Gene Expression and Regulation
- Gene expression is the process by which information from a gene is used to synthesize a functional gene product, typically a protein.
- Gene regulation is the process of controlling the expression of genes.
- Gene regulation is crucial for responding to environmental changes, cell differentiation, and development.
mRNA Processing
- Pre-mRNA undergoes several processing steps to become mature mRNA:
- 5' capping: A 7-methylguanosine cap is added to the 5' end for protection and ribosome binding.
- 3' polyadenylation: A string of adenine nucleotides (poly(A) tail) is added to the 3' end for stability.
- Splicing: Introns (non-coding regions) are removed, and exons (coding regions) are joined together.
- mRNA is then exported from the nucleus and transported to the cytoplasm.
Translation
- Translation is the process of protein synthesis.
- It involves decoding the mRNA sequence into a polypeptide chain.
- Ribosomes, tRNAs, and amino-acyl tRNAs are involved in the process.
- Ribosome has three binding sites (E, P, and A) where tRNAs bind during translation.
Translation Initiation (Prokaryotes)
- Initiation factors (IF1, IF2, IF3) bind to the 30S subunit.
- mRNA and initiator methionyl-tRNA (fMet-tRNA) bind to the complex.
- The 50S subunit joins to form a complete 70S ribosome.
Translation Initiation (Eukaryotes)
- Eukaryotic mRNAs have a 5' cap that's recognized by initiation factors to bind to 40S subunit.
- Small ribosomal subunit scans along the mRNA until it reaches the AUG codon.
- Methionyl tRNA is then attached to create the initiator complex.
- The large subunit joins to form a 80S ribosome complex.
Translation Elongation
- Aminoacyl-tRNA binds to the A site.
- Peptide bond formation between the amino acids on the tRNAs at the P and A sites.
- The ribosome translocates along the mRNA, shifting the tRNAs from the A and P sites to the E and P sites, respectively.
- The uncoupled tRNA is released from the E site.
Translation Termination
- A stop codon is reached on the mRNA.
- Release factors bind to the A site. -The polypeptide chain is released.
- Ribosome dissociates.
Components of translational process
- Amino-acyl tRNA: carries amino acids to the ribosome.
- Ribosome: translates mRNA into protein.
- Ribosome large subunit and small subunit.
- mRNA: carries genetic information from DNA to ribosome
- GTP: an energy source.
- Protein factors: help facilitate various steps of translation.
tRNA Structure and Synthesis
- tRNAs are small RNA molecules with a cloverleaf shape.
- They have an anticodon that base-pairs with the mRNA codon.
- tRNAs are aminoacyl-tRNA-synthetase-specific.
- Transfer of an amino acid to tRNA is catalyzed by aminoacyl-tRNA synthetases.
Ribosome Structure
- Ribosomes are composed of rRNA and ribosomal proteins.
- Prokaryotes have 70S ribosomes (50S + 30S subunits).
- Eukaryotes have 80S ribosomes (60S + 40S subunits).
- The structure of rRNA is critical for its catalytic function (peptidyl transferase).
Control of Gene Expression
- Regulation at different levels (transcription, processing, translation).
- Prokaryotes use operons for transcription regulation.
- Eukaryotes use chromatin structure and transcription factors to regulate gene expression.
- Post-transcriptional control can also occur at different stages.
Online resources
- Useful links to supplementary websites and educational videos for further learning about the topic.
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Description
Test your knowledge on gene expression, regulation, and mRNA processing. This quiz covers the fundamental processes that transform genetic information into functional proteins, including translation and the importance of each step. Improve your understanding of molecular biology concepts with this engaging quiz.
