Intracellular sorting and transport Flashcards
Protein synthesis and sorting to compartments; nucleo-cytoplasmic transport; vesicular transport – exocytosis and endocytosis.
What is unique about eukaryotic cells regarding compartmentalization?
Eukaryotic cells are highly compartmentalized and chimeric, with nuclear, endogenous, and exogenous mitochondria.
What is cell fractionation, and how is it achieved?
Cell fractionation separates cell structures by centrifuging at high speeds to isolate smaller structures based on density differences.
Why do organelles have specific protein complements?
Organelles have specific proteins to sort other proteins accurately, often through intracellular sorting processes like gated, transmembrane, and vesicular transport.
What are the main types of protein transport within cells?
Gated (e.g., nuclear pores)
Transmembrane
Vesicular
Engulfment
What are signal sequences?
Signal sequences are short amino acid stretches that direct proteins to specific cell locations, usually found at the N-terminus of the protein.
What happens if a protein has the wrong signal sequence?
The protein will accumulate in the cytosol or end up in the wrong compartment.
How do large molecules enter the nucleus?
They require specific signal sequences for nuclear import through the Nuclear Pore Complex (NPC).
What is a regulated nuclear localization?
A system where nuclear localization signals only activate under specific conditions, allowing proteins to enter the nucleus.
What is co-translational transport?
The process where proteins are transported across membranes as they are being synthesized by ribosomes.
What are the main types of post-translational modifications?
N-glycosylation on asparagine
O-glycosylation on serine and threonine
What are the possible destinations for proteins after synthesis?
Proteins can remain in the cytosol, be transported to organelles, or be secreted, depending on signal sequences and transport mechanisms.
