Organelles Flashcards
1
Q
How are proteasomes structured?
A
- Barrel shaped protein that degrades poly ubiquinated proteins
2
Q
What are the autophagies of different components called?
A
- Proteaphagy degrades proteasomes
- Lipophagy degrades lipid droplets
- Pexophagy degrades peroxisomes
- Xenophagy degrades invaders
- Mitophagy degrades mitochondria
- Ribophagy degrades polyribosomes
- Lysophagy degrades lysosomes
- Aggrephagy degrades protein aggregates
- Ferritinophagy degrades ferritin(main storage complex, common in liver)
3
Q
What’s the difference between constitutive and substrate specific autophagy?
A
- Constitutive regulates general level of components based on needs
- Substrate specific use eat me signals
4
Q
What are the effects and signals of mTORC1?
A
- Signals from: rapamycin, oxygen, glucose, AA, ATP
> Associates to lysosome via RagA/C AA indicators
> Insulin releases Rheb which activates - Causes: biosynthesis, translation
- Inhibits: autophagy
5
Q
What are the effects and signals of mTORC2?
A
- Signals from: insulin, growth factors, blocked by chronic rapamycin
- Causes: lipid and glucose metabolism for survival
- Main global pathway of AA regulation
6
Q
How does mTORC1 regulate autophagy?
A
- Phosphorylates early autophagy pathway (ULK1 and ATG13)
- Lack of nutrients stops inhibition
7
Q
How does mTORC1 interact with the lysosome?
A
- Cytosolic when inactive(starvation)
- Lysosome releases AA in normal circumstances, acts as indicator of nutrients
- Absence of AA and mTORC1 reduces efflux from lysosome
8
Q
What does the AMPK pathway do?
A
- Alternate nutritional signaling pathway
- AMP dependent kinase makes use of increased levels of AMP
- Reactivates mt biosynthesis and reduces ATP consumption
9
Q
What are the proteins regulating mt fusion and fission?
A
- dynamin GTPase superfamily
- Outer membrane fusion: Mitofusin 1/2
- Inner membrane fusion: Opa1
- Fission: Drp
10
Q
How are mt Cristae dynamic?
A
- Move, form and dissappear
- Higher membrane potentials that vary between cristae
- Makes each cristae an independent bioenergetic unit
11
Q
How do mt position themselves in the cell?
A
- Move to place of highest need via cytoskeleton
- Glucose inhibits movement
- Ca2+ also inhibits movement, allows them to detach and localize near active synapses
- Ca2+ also signals mt activity
12
Q
When are mt autophagised?
A
- Starvation, also induces mt fission
- Quality control when mt depolarise and fail to degrade PINK1
- Miro continously removed from mt surface, when not induces autophagy
13
Q
How is the ER distributed through the cell?
A
- Tubular smooth ER connects through entire cell
- ER sheets are actually just really dense tubules
- Takes up 35% of volume, constantly changing
- Explores 95% of cytoplasmic volume in 15 min
- Links membrane bound organelles including lipid droplets
14
Q
How extensive are mts in the cytoplasm?
A
- Constantly moving to areas of demand
- Only other organelle that contacts all other organelles
15
Q
How does the ER mediate, and mediated organelle dynamics?
A
- Mediate mt fission
- Also extended by lysosome
- Transfers lipids between organelles using lipid transfer/exchange proteins
- ER synthesizes most lipids, so convenient
