31 Questions
What is the primary function of exoribonuclease-mediated degradation in MRNA degradation pathways?
To degrade MRNA from the 3' end
Which of the following initiation factors is NOT involved in MRNA recruitment to the ribosome?
eIF5
What is the primary influence on ribosome binding to MRNA?
All of the above
What is the primary mechanism by which transcriptional regulation influences protein synthesis?
By regulating the amount of MRNA available for translation
What is the primary function of the translation initiation complex?
To assemble the ribosome and MRNA
Which of the following is NOT a mechanism of transcriptional regulation?
Initiation factor binding to MRNA
In eukaryotes, what is the primary location of mechanisms related to translation regulation?
5’ UTR
What is the term that represents the capacity of ribosomes to generate proteins from individual mRNAs?
TLRi
What is the primary factor that determines the concentration of a protein in a cell?
Equilibrium between synthesis and degradation rates
What is the purpose of polyubiquitination in protein regulation?
To mark proteins for degradation
What is the relationship between the constant of degradation (Kd) and protein concentration?
Higher Kd leads to lower protein concentration
What is the primary level at which translation regulation occurs?
At the initiation of translation
How do viruses like polio exploit the host cell's translation machinery?
By blocking the host cell's translation initiation complex
What is the primary role of the eIF4E protein in translation initiation?
To recognize and bind to the mRNA cap
What is the effect of phosphorylation of the eIF2 protein on translation initiation?
It decreases the recruitment of the 43S complex
What is the primary mechanism by which cells regulate translation in response to stress or cellular signals?
Modulating the phosphorylation of the eIF2 protein
What is the effect of coronavirus infection on cellular translation?
Selective translation of viral proteins through IRES-mediated initiation
What is the function of the proteína N in coronavirus-infected cells?
To stimulate translation of viral mRNAs through CAP-dependent initiation
What is the role of IRES-mediated translation during cellular stress?
To selectively translate specific mRNAs that respond to stress
How do microRNAs regulate translation initiation?
By inhibiting eIF4E function
What is the effect of eIF4E binding protein (4EBP) on translation initiation?
To inhibit CAP-dependent translation
What is the effect of activating quinasas such as PKR, HRI, and GCN2 on eIF2?
It reduces translation by inactivating eIF2.
What is the function of GCN2 in eukaryotes?
It detects tRNAs without amino acids and phosphorylates eIF2 to reduce translation.
What is the effect of GCN2 on the translation of mRNAs encoding enzymes for amino acid biosynthesis?
It has no effect on their translation.
What is the purpose of the quinasa that phosphorylates eEF2?
To reduce energy consumption by inactivating eEF2 when nutrients are lacking.
What is the consequence of failing to regulate eEF2 activity?
The cell is susceptible to death due to excessive energy consumption.
What is the role of 4E-BP in mRNA translation?
To repress translation by binding to eIF4E
What is the effect of mTOR on translation?
Stimulation of translation by phosphorylating S6K
What is the role of eIF2 in translation initiation?
To form the 43S pre-initiation complex
What is the effect of phosphorylating eIF2 on translation?
Inhibition of translation by reducing eIF2 activity
How does the HRI kinase regulate translation in erythrocyte precursors?
By phosphorylating eIF2 to inhibit translation
Study Notes
Protein Synthesis Regulation
MRNA Degradation
- MRNA degradation is a crucial step in regulating protein synthesis
- MRNA degradation pathways:
- Exoribonuclease-mediated degradation
- Endoribonuclease-mediated degradation
- Decay-initiating RNase-mediated degradation
- MRNA degradation rates can be influenced by:
- MRNA sequence and structure
- Binding of RNA-binding proteins
- MicroRNA-mediated degradation
Initiation Factors
- Initiation factors are proteins that facilitate the initiation of translation
- In eukaryotes, initiation factors include:
- eIF1
- eIF1A
- eIF2
- eIF3
- eIF4A
- eIF4B
- eIF4E
- eIF4G
- Initiation factors play a crucial role in:
- MRNA recruitment to the ribosome
- Start codon recognition
- Assembly of the translation initiation complex
Ribosome Binding
- Ribosome binding is the process by which the ribosome binds to the MRNA
- Ribosome binding is influenced by:
- MRNA secondary structure
- Binding of RNA-binding proteins
- Initiation factors
- Ribosome binding is a critical step in translation initiation
Transcriptional Regulation
- Transcriptional regulation is the regulation of gene expression at the level of transcription
- Transcriptional regulation can occur through:
- Transcription factor binding to specific DNA sequences
- Chromatin remodeling
- Epigenetic modifications
- Transcriptional regulation can influence protein synthesis by:
- Regulating the amount of MRNA available for translation
- Influencing the stability and translation efficiency of MRNA
Translation Initiation Complex
- The translation initiation complex is a complex formed by the ribosome, MRNA, and initiation factors
- The translation initiation complex is crucial for:
- Recognizing the start codon
- Assembling the ribosome and MRNA
- Initiating protein synthesis
- The translation initiation complex is regulated by:
- Initiation factors
- MRNA sequence and structure
- Ribosome binding
This quiz covers the regulation of protein synthesis, including mRNA degradation, initiation factors, ribosome binding, transcriptional regulation, and translation initiation complex. Explore the different mechanisms that control protein synthesis in cells.
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