Answer: It tags damaged proteins for proteasomal degradation.
- A It directly refolds misfolded polypeptides back into their native conformation
- B It tags damaged proteins for proteasomal degradation
- C It functions as a molecular chaperone that shields nascent chains from aggregation
- D It binds ribosomes to halt ongoing translation of damaged mRNA transcripts
Correct answer: B. It tags damaged proteins for proteasomal degradation
Explanation: Ubiquitin is a small protein that marks damaged or misfolded proteins for degradation by the 26S proteasome. Poly-ubiquitination signals rapid destruction.
As substrate concentration rises, reaction rate increases steeply at first, then plateaus at Vmax once every enzyme molecule is working at full capacity; Km is the substrate concentration giving half-maximal rate, and a LOWER Km means the enzyme reaches that rate with less substrate (higher affinity).
Concept context
Carbohydrates, proteins, lipids, nucleic acids, and enzyme kinetics. Essential foundation for understanding metabolism.