Untitled Quiz
21 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the role of chaperones in protein folding?

  • They provide a structural framework for proteins.
  • They assist in the proper folding of misfolded proteins using ATP. (correct)
  • They degrade improperly folded proteins immediately.
  • They chemically modify proteins to enhance their function.

Which statement about hydrophobic amino acids in proteins is true?

  • They facilitate interactions with small molecules.
  • They are essential for the phosphorylation of proteins.
  • They are always located on the protein surface.
  • They contribute to protein stability by being buried in the core. (correct)

What is the consequence of improperly folded proteins?

  • They enhance cellular activities.
  • They increase the protein synthesis rate.
  • They can aggregate and become toxic to cells. (correct)
  • They are always recognized and corrected by ribosomes.

What is the function of the proteasome?

<p>To degrade misfolded proteins marked by hydrophobic residues. (B)</p> Signup and view all the answers

How do heat-shock proteins (Hsp) respond to cellular stress?

<p>They are synthesized in larger quantities. (B)</p> Signup and view all the answers

What effect does the presence of exposed hydrophobic residues have on a protein?

<p>It marks the protein for degradation by the proteasome. (A)</p> Signup and view all the answers

Which of the following statements is false regarding post-translational regulation?

<p>All proteins must undergo chemical modification after synthesis. (A)</p> Signup and view all the answers

Which factor is least likely to interfere with protein folding?

<p>Presence of molecular chaperones. (D)</p> Signup and view all the answers

Which of the following processes is NOT involved in the regulation of the proteome?

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

What role does protein phosphorylation play in cellular regulation?

<p>It activates or deactivates proteins. (A)</p> Signup and view all the answers

What initiates the process of translation in eukaryotes?

<p>Formation of the ribosomal complex with eIF2. (A)</p> Signup and view all the answers

Which mechanism is NOT a form of translational regulation in prokaryotes?

<p>Polyadenylation of mRNA (D)</p> Signup and view all the answers

The role of aconitase in eukaryotic translation is to:

<p>Block translation when iron levels are low. (C)</p> Signup and view all the answers

Which of the following components plays a crucial role in the formation of the eukaryotic initiation complex?

<p>eIF2 complexed with GTP (A)</p> Signup and view all the answers

How does the phosphorylation of eIF2 impact translation?

<p>It sequesters eIF2B, leading to reduced translation. (C)</p> Signup and view all the answers

Which of these mechanisms is indicative of post-translational regulation?

<p>Phosphorylation of proteins. (A)</p> Signup and view all the answers

What is the main function of molecular chaperons in protein synthesis?

<p>To assist in protein folding and modification. (A)</p> Signup and view all the answers

Which sequence is specifically mentioned as being important in prokaryotic translational regulation?

<p>Shine-Dalgarno sequence (A)</p> Signup and view all the answers

What is the potential consequence of the environmental stress on protein expression?

<p>It may induce the upregulation of specific stress response proteins. (D)</p> Signup and view all the answers

In eukaryotic cells, which process does NOT contribute to gene expression regulation?

<p>Elongation of the mRNA (D)</p> Signup and view all the answers

What distinguishes regulatory GTP-binding proteins from other proteins?

<p>They are switched on and off by phosphate groups. (C)</p> Signup and view all the answers

Study Notes

Genome Expression Regulation

  • The proteome reflects the expression of the genome and transcriptome
  • Proteome differences between tissues are represented with red (common proteins) and blue (tissue specific proteins)
  • The regulation of genome expression involves multiple steps: organization, transcription, RNA splicing, translation, protein sorting, and post-translational modification

Translational Regulation

  • Prokaryotes and eukaryotes use translational control mechanisms
  • Prokaryotes use a Shine-Dalgarno (SD) sequence upstream of the AUG start codon for translation initiation
  • Translational regulation in prokaryotes can involve:
    • RNA binding proteins blocking access to the SD sequence
    • Temperature-regulated RNA structures (e.g., Listeria monocytogenes)
    • Riboswitches (e.g., S-adenosyl methionine)
    • Antisense RNA (e.g., iron storage proteins) which base-pairs with mRNA to block the SD sequence

Translational Regulation: Eukaryotes

  • Eukaryotes lack Shine-Dalgarno sequences
  • Repressor proteins can bind near the initiator AUG to inhibit translation, or interfere with 5' cap and 3' poly-A tail interactions
  • Small RNA molecules (microRNAs or miRNAs) regulate eukaryotic translation
  • Eukaryotic initiation factors (eIFs) regulate translation:
    • eIF2 plays a crucial role in translation initiation, forming a complex with GTP and initiator tRNA
    • GTP hydrolysis causes a conformational change in eIF2, leading to its release as an inactive GDP-bound form
    • Reactivation of eIF2 requires eIF2B, a guanine nucleotide exchange factor (GEF) that promotes GDP-GTP exchange
    • However, phosphorylation of eIF2 can sequester eIF2B, forming an inactive complex and inhibiting translation

Post-Translational Regulation: Proteins

  • Proteins undergo post-translational modifications to become functional, including:
    • Proper folding into 3-D structure
    • Covalent modifications with chemical groups (e.g., sugars, phosphate)
    • Interactions with other proteins and small molecules (cofactors)

Post-Translational Regulation: Protein Folding

  • Hydrophobic amino acids are buried in the protein interior core
  • Folding can begin during translation for some proteins or after synthesis
  • Chaperones (e.g., Hsp70 and Hsp60) assist with protein folding:
    • Interact with exposed hydrophobic residues of misfolded proteins
    • Utilize ATP hydrolysis for proper folding
  • Misfolded proteins can aggregate and become toxic
  • The proteasome is a protein degrading apparatus that targets misfolded proteins:
    • Misfolded proteins display exposed hydrophobic residues, leading to proteasome recognition
    • Proteasome degradation competes with chaperone interactions, and the longer a protein takes to fold, the higher the chance of degradation

Review Question

  • Treatment with HSP inhibitors should reduce protein degradation
  • Treatment with an iron chelator should decrease ferritin transcription
  • Treatment with a miRNA complementary to eIF2B should result in an increase in transcription

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

More Like This

Untitled Quiz
37 questions

Untitled Quiz

WellReceivedSquirrel7948 avatar
WellReceivedSquirrel7948
Untitled Quiz
55 questions

Untitled Quiz

StatuesquePrimrose avatar
StatuesquePrimrose
Untitled Quiz
18 questions

Untitled Quiz

RighteousIguana avatar
RighteousIguana
Untitled Quiz
48 questions

Untitled Quiz

StraightforwardStatueOfLiberty avatar
StraightforwardStatueOfLiberty
Use Quizgecko on...
Browser
Browser