Organelle Ecology - organelles without membranes Flashcards
(17 cards)
nucleolus structure
granular compartment, with fibrillar centres surrounded by dense fibrillar components
granular component function
pre-ribosome assembly
fibrillar centre function
rRNA transcription
dense fibrillar component function
pre-rRNA processing
NOR
nucleolar organiser region- bit of chromosome which makes rDNA
ribosome biogenesis
pre-rRNA transcription (RNAPI), cleavage and assembly into complexes, cut up into individual rRNAs/modified, complex forms
how mucht nucleolar components be organised
phase condensation
phase condensation evidence
bit shaky- but stuff like nucleoli showing liquid-like properties from microscopy, molecular exchange observed with FRAP, sedimentation
drivers of phase separation
repeated modular domains (‘threshold’ when molecules start to interact and condense), intrinstically disordered regions
candidate drivers for LLPS in the nucleolus
fibrillarin (have inherently disordered regions), nucleophosmin (scaffold protein in granular component)
how are nucleoli formed
sequentially, inside-out- FC, DFC, GC
another example of phase condensation
P granules in the first few C elegans divisions- segregated into the germline
proteins involved in P granule formation
MEX5- destabilises P granule formation at the anterior, PAR-1 stops this protein existing at the posterior, so only get them at P end
example in algae
pyrenoid- RuBisCO localising structure, can see droplet-like activity under the microscope, doesn’t seem to be a crystalline organisation of RuBisCO like you’d expect
how strong is evidence
not very- a lot of it is qualitative, about droplets looking round/fusing like a liquid
alternatives to llps
direct protein-protein interactions (site-specific)
technological exploitation
can make organelles which ‘pack’ whatever product (e.g. plastics, maybe?)
