Translation in Eukaryotes Lecture 1 Quiz

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Questions and Answers

What is the main focus of Dr. Hannah Burgess's lecture on Translation in Eukaryotes?

  • Recap of the overall translation process
  • Overview of translation in eukaryotes and the function of key translation initiation factors (eIFs) (correct)
  • Comparison of eukaryotic and prokaryotic ribosomes and mRNAs
  • Additional translational control mechanisms

What is the primary objective of Alberts' chapter 'Control of Gene Expression' in the Molecular Biology of the Cell, 7th Edition?

  • Comparison of eukaryotic and prokaryotic ribosomes and mRNAs
  • Additional translational control mechanisms (correct)
  • Recap of the overall translation process
  • Overview of translation in eukaryotes and the function of key translation initiation factors (eIFs)

What does Dr. Hannah Burgess emphasize as a crucial aspect of Translation in Eukaryotes?

  • Understanding the similarities and differences between eukaryotic and prokaryotic ribosomes and mRNAs
  • Investigating additional translational control mechanisms
  • Recap of the overall translation process
  • The function of key translation initiation factors (eIFs) (correct)

What is the specific content covered in Alberts' chapter 'From RNA to Protein' in the Molecular Biology of the Cell, 7th Edition?

<p>Overview of translation in eukaryotes and the function of key translation initiation factors (eIFs) (A)</p> Signup and view all the answers

Which organelle is responsible for the turnover of damaged or unfolded proteins, largely achieved by the proteasome?

<p>Endoplasmic Reticulum (C)</p> Signup and view all the answers

What is responsible for tagging proteins with lysine 48-linked ubiquitin molecules for proteasomal destruction?

<p>Ubiquitin Ligases (D)</p> Signup and view all the answers

In the context of protein stability, what contributes to overall protein levels and can be a target of control?

<p>Protein turnover (B)</p> Signup and view all the answers

What is the role of the Signal Recognition Particle (SRP) in the process of protein secretion?

<p>Directing nascent proteins to the endoplasmic reticulum (ER) (B)</p> Signup and view all the answers

What is the main organelle involved in targeting proteins to be secreted to the ER?

<p>Endoplasmic Reticulum (B)</p> Signup and view all the answers

Which step of translation initiation is considered the most regulated?

<p>Cap recognition (C)</p> Signup and view all the answers

What ensures correct start codon selection during translation initiation?

<p>$eIF2-GDP$ recycling (A)</p> Signup and view all the answers

What is targeted for destruction by the proteasome?

<p>Damaged or unfolded proteins (D)</p> Signup and view all the answers

What is the size of eukaryotic ribosomes?

<p>80S (A)</p> Signup and view all the answers

Which complex is responsible for recognizing the 5' cap on the mRNA during translation initiation?

<p>eIF4F complex (A)</p> Signup and view all the answers

What is the essential part of the translation initiation process during AUG recognition?

<p>Ternary complex (B)</p> Signup and view all the answers

Which step in translation initiation involves the formation of a pre-initiation complex?

<p>Ribosome recruitment (D)</p> Signup and view all the answers

Which step in translation initiation involves the recognition of the start codon of the mRNA by the ribosome?

<p>AUG recognition (A)</p> Signup and view all the answers

What contributes to overall protein levels and is an example of protein control?

<p>Ubiquitination (C)</p> Signup and view all the answers

What pathway ensures correct translation and prevents the production of incorrect or harmful proteins?

<p>Surveillance pathways (B)</p> Signup and view all the answers

Flashcards

Eukaryotic Ribosome

Eukaryotic ribosomes are larger (80S) and consist of a 60S large subunit and a 40S small subunit.

Prokaryotic Ribosome

Prokaryotic ribosomes are smaller (70S) and consist of a 50S large subunit and a 30S small subunit.

Cap Binding

The eIF4F complex, consisting of eIF4E, eIF4G, and eIF4A, recognizes the 5' cap on the mRNA during translation initiation.

Ribosome Recruitment

It involves the 40S ribosomal subunit, eIF3, eIF5, and a GTPase-activating protein, bridging the mRNA and ribosome for AUG selection.

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AUG Recognition

The ribosome recognizes the start codon (AUG) of the mRNA, facilitated by the ternary complex (initiation factors and charged tRNA).

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mRNA Scanning

The ribosome scans the mRNA to locate the start codon (AUG), which is crucial for initiating translation correctly.

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Translation Initiation

This is the slowest step in translation and is often controlled to regulate protein production.

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Protein Stability Control

The process includes ubiquitination, where proteins are tagged for degradation, influencing overall protein levels.

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Central Dogma

DNA -> RNA -> Protein. Describes the flow of genetic information in biological systems.

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Translation Components

Ribosomes, mRNA, translation factors, tRNA, amino acids, ATP, and GTP.

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Surveillance Pathways

Pathways that monitor translation to ensure that correct proteins are produced, preventing errors or harmful products.

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Specialized Ribosomes

Ribosomes aren't uniform; variations in RNA polymerase paralogs and ribosome composition lead to specialized ribosomes.

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eIF4F Complex

Consists of the cap binding protein eIF4E, the scaffolding protein eIF4G, and the helicase eIF4A.

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tRNA Function

tRNA carries amino acids to the ribosome, matching the mRNA codon to add the correct amino acid to the polypeptide chain.

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Role of GTP in Translation

GTP provides the energy required for various steps of translation, similar to ATP.

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Ribosome Heterogeneity

Variations in ribosome composition can lead to specialized functions in different cell types or conditions.

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Ternary Complex

This complex includes initiation factors and a charged transfer RNA (tRNA), facilitating the start codon recognition.

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Role of eIF3 and eIF5

eIF3, eIF5, and a GTPase-activating protein are crucial for assembling the pre-initiation complex.

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Translation Objectives

This involves understanding differences in ribosome structure, recognizing translation phases, and knowing the steps of translation initiation.

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Study Notes

  • The text discusses the differences between bacterial and eukaryotic ribosomes and translation factors, and covers the three phases of translation, specifically initiation, in eukaryotic cells.
  • Eukaryotic ribosomes consist of an 80S large ribosome, which includes a 60S large subunit and a 40S small subunit, as well as various RNAs and proteins.
  • Prokaryotic ribosomes, on the other hand, are smaller, with a 70S ribosome made up of a 50S large subunit and a 30S small subunit.
  • Learning objectives outlined in the text include understanding the differences between bacterial and eukaryotic ribosomes and translation factors, the three phases of translation, and the key steps of eukaryotic translation initiation.
  • Translation initiation involves several steps, including cap binding, ribosome recruitment, AUG recognition, and tRNA delivery.
  • Cap binding involves the eIF4F complex, which consists of the cap binding protein eIF4E, the scaffolding protein eIF4G, and the helicase eIF4A. Cap binding is responsible for recognizing the 5' cap on the mRNA.
  • Ribosome recruitment involves the formation of a pre-initiation complex, which includes the 40S small ribosomal subunit, eIF3, eIF5, and a GTPase-activating protein. This complex bridges the mRNA and the ribosome, which allows for AUG selection.
  • AUG recognition involves the recognition of the start codon of the mRNA by the ribosome, which is facilitated by the ternary complex, which consists of the initiation factors and a charged transfer RNA (tRNA).
  • The scanning of the mRNA by the ribosome, in search of the start codon, is an essential part of the translation initiation process.
  • The text also mentions that translation initiation is the rate-limiting step and a frequent target of regulation.
  • Protein stability contributes to overall protein levels. An example of protein control is the ubiquitination and degradation of proteins.
  • The central dogma outlines the flow of genetic information from DNA to RNA to protein.
  • Translation involves the use of ribosomes, mRNA, translation factors, tRNA, amino acids, and energy sources such as ATP and GTP.
  • Surveillance pathways are in place to ensure correct translation and to prevent the production of incorrect or harmful proteins.
  • The history of ribosome research began in the 1970s with biochemical investigation, and continued with the first high-resolution structure of the ribosome in 2009, which led to the deciphering of translation pathways and the unravelling of antibiotic modes of action.
  • Ribosomes are not as homogenous as once thought and there are many RNA polymerase paralogs produced in higher eukaryotes, as well as variations in ribosome composition, leading to "specialized ribosomes".

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