Chapter 8 Flashcards
What is the Endomembrane system composed of?
ER, Golgi complex, and dissolves, lysosomes, and vacuoles
What is the biosynthetic pathway?
Proteins are synthesized in the ER, modified a Golgi complex and transported to various destinations
What is the secretory pathway?
Protein synthesized in ER are discharged from cell
What is the endocytic pathway?
Materials move from outer surface of cell to compartments, endosomes and lysozymes
What are the two secretion modes?
Consecutive secretion and regulated secretion
What is consecutive secretion?
Materials transported in secretary vesicles and discharged in continual manner
What is regulated secretion?
Materials are stored in vesicles and discharged in response to stimulus
Where does regulated secretion occur?
Endocrine cell (hormones), pancreatic acinar cells (digestive enzymes), and never cells (neurotransmitters)
How can secreted materials be stored?
In large, densely packed, membrane-bound secretory granules
How are proteins, lipids, and complex polysaccharides transported through the cell?
Along the biosynthetic or secretory pathways
What is autoradiography?
Visualize biochemical processes by radioactively labelling molecules
What did autoradiography show?
Endoplasmic reticulum as site where secretory proteins synthesis occurred
What are GFPs?
Fluorescent proteins, allows microscope’s viewing of protein movement in living cells
What is the endoplasmic reticulum?
Network of membranes that penetrates much of cytoplasm and has a lumen separated from cytosol by ER membrane
What are the two compartments of the ER membrane?
The rough ER and the smooth ER
Describe the rough ER
Ribosomes bound to cytosolic surface, flattened sacs connected to neighbors, continuous with outer membrane of nuclear envelope
Describe smooth ER
Lacks ribosomes, membranes highly curved and tubular, continuous with RER
What is the SER functions?
- Steroid hormone synthesis in endocrine cells of the gonad an adrenal cortex
- Detoxification of organic compounds in liver
- Calcium ions sesquastation and regulated release
What is the starting point of biosynthetic pathways for secretory proteins?
The RER
What is co-translational translocation?
Proteins are synthesized at our ER and released into ER lumen
The ER bound ribosomes synthesize what?
Integral membrane proteins
How are integral membrane proteins synthesized?
Co translationally, and hydrophobic transmembrane segments are shunted from translocation into lipid bilayer
What are tail anchored proteins?
Lack signal sequence, are synthesized in cytoplasm, and targeted to ER through interactions with proteins in GET pathway
How do membranes arise?
From other membranes