Autophagy activated under nutrient-rich conditions

Question

BlackTom AI · Accepted Answer

The statement given is: 'Autophagy activated under nutrient-rich conditions.'

In cellular biology, autophagy is a catabolic process that recycles cellular components by delivering them to lysosomes for degradation. This process is typically upregulated when cells experience nutrient deprivation or stress, such as amino acid or glucose scarcity, energy deficit, or other unfavorable conditions. Under nutrient-rich conditions, growth signaling pathways (notably mTOR) promote anabolic processes and actively suppress autophagy to favor cell growth and biosynthesis.

Exploring why this statement is unlikely:
- Nutrient abundance signals promote growth rather than recycling; autophagy is downregulated to avoid unnecessary degradation of cellular components when resources are plentiful.
- Mechanistically, mTOR complex 1 (mTORC1) activity is high with ample nutrients, which inhibits the initiation of autophagy by phosphorylating and inactivating components of the autophagy initiation complex.
- Conversely, nutrient scarcity lowers mTORC1 activity and activates ULK1 complex and downstream autophagic machinery, leading to increased autophagy.

Given these established regulatory relationships, the claim that autophagy is activated under nutrient-rich conditions contradicts the well-supported understanding of autophagy physiology. Therefore, the statement is not correct.

Note: If there were multiple answer choices, we would evaluate each one against these principles, but in this case only the single assertion is presented for true/false assessment.

2261 BIOSC 1500 SEC1030 Cell Bio 1500'25 first midterm, 75 min version

Autophagy activated under nutrient-rich conditions

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