Lecture 5 (no recording)
*Cytosol - half the cell volume
- protein synthesis and degradation
- intermediary metabolism (degradation and synthesis of small molecules)
-not an organelle
(cytosol-mitochondria-rough ER- smooth ER, Nucleus—Peroxixomes, Lysosomes, endosomes)
*Organelle: A subcellular compartment or large macromolecular complex, often
membrane-enclosed, that has a distinct structure, composition, and function.
* Examples of membrane-enclosed organelles:
- Endoplasmic Reticulum
- Golgi Apparatus
*Examples organelles that are not membrane-bound:
*lysosome/vacuole(in plants): digestive enzyme
*Golgi apparatus: modifies proteins and lipids
*mitochondrion: used for ATP synthesis
*nucleus: DNA/RNA synthesis
*RER(tough Endoplasmic reticulum): synthesis of various proteins
*SER(smooth endoplasmic reticulum): phospholipid synthesis, detoxification
*endosome: endocytosis, absorbs other molecules by engulfing them
*peroxisome: used in various oxidative reactions
*polyribosomes: used for protein synthesis *rough ER is the most abundant membrane in Eucaryotic cells
Ppt7 [Intracellular compartments are Dynamic]
+topologically equal spaces are in pink in the diagram.
*3 Mechanisms of moving from one organelles to another
1. Gate transport
Move b/w cytosol and nucleus through nucleus pore complexes (a selective gate) in nuclear envelope.
2. Transmembrane transport
-Transmembrane protein translocatiors directly transport specific proteins across a
memebrame from cytosol into a space that is topologically distinct.
-ex) protein from cytosol into the ER lumen or mitochondria
3. Vesicular transport
-A spherical transport vesicles ferry proteins from one compartment to another.
-They discharge by fusing with the membrane of 도착지.
-Ex) transfer of soluble protein from ER to Golgi Apparatus
-Vesicular transport can move proteins only b/w compartments that are topologically
equivalent, since the transported proteins do not cross membrane, (but fuse)
+++topologically equivalent: 모양은 다르나, 구조적으로는 같은
Ppt8 +Endomembrane: 세포내막계
*composed of endosome, peroxisome, ERs, Golgi apparatus, lysosome/vacuoles
*Involved in 2 main pathways:
A) Biosynthetic/Secretory pathways
–Biosynthesis: Proteins and lipids made in the ER delivered to the membranes of other
•helps secreted proteins move out of the cell through exocytosis
B) Endocytic Pathway
•move contents into cell through endocytosis Ppt10
*vesicles: membrane-enclosed organelle that transports components in endomembrane system
*exocytosis: transport vesicle content delivered to extracellular space, vesicle membrane fused w
cell plasma membrane, ―secretion‖
*endocytosis: cell plasma membrane forms vesicle membrane, vesicle contents come from
extracellular space, ―engulfing‖
[How are specific proteins targeted to different organelles?]
-mRNA arrives in the cytoplasm and translation starts on ribosomes in the cytosol.
-A cytosolic protein: (in general) translated in cytosol and stay in cytosol
[sorting proteins to