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Lecture

Notes taken during lecture


Department
Biology
Course Code
BIO120H1
Professor
Jean Jiang Nash

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LECTURE Feb. 8, 2011
***Read figure legends in textbook before class for next, next lecture***
Exocytosis
Lipids
Vesicles move to plasma membrane to deliver cargo, including lipids
oBring lipids from synthesis at ER to Golgi to vesicles
Membrane proteins
Secreted soluble proteins
2 types of exocytosis
Constitutive always on, always functional, default
oIf protein is synthesized into ER lumen and has only ER signal sequence,
now soluble protein, its default fault is to be secreted in constitutive
secretive pathway
oBe secreted
Regulated e.g. insulin
oThose vesicles stay in cytosol, wait for signal
Constitutive secretory pathway
No sorting signal ends up in cytosol
So default pathway sentence should be changed for proteins with a ER signal
sequence and no other sorting signal
Regulated secretory pathway
Vesicles sitting under plasma membrane, waiting for signal
Vesicles fuse with plasma membrane
Found as aggregates in TransGolgi network
Next slide
Fusing to release insulin
Beta cell in pancreas
Beta cells waiting under plasma membrane to release glucose
oImmediate response
oV. quick compared with gene transcription, translation, etc.
oInsulin looks like a big ball of precipitate
oComes apart in neutral pH environment now in acidic environment
oIncrease in Ca levels causes vesicles to fuse
ENDOCYTOSIS
Process of maturation depends on brining hydrolytic enzymes from
Must have acid hydrolyase to be lysosome
Two types
PHAGOCYTOSIS
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