Endomembrane system I - Key organelles Flashcards
percentage of eukaryotic genes directly involved in the endomembrane system
10-20%
origin of endomembrane organelles
endogenous
origin of mitochondria and chloroplast organelles
symbiotic
What proteins get delivered to the ER
proteins that will become plasma membrane proteins
proteins that will be secreted out of the cell
Rough endoplasmic reticulum
- studded with ribosomes translate and translocate proteins
- controlled environment for protein folding
- continuous with the outer membrane of the nuclear envelope
How do proteins get from the ER to extracellular space or to the plasma membrane?
vesicle trafficking
membrane vesicle size
30-100nm
Smooth ER
site of cellular lipid and sterol synthesis
Golgi Apparatus structure
series of flattened sacks called cisternae
Functionally compartmentalised with cis, medial and trans cisternae
Cis golgi is where
proteins and lipids arrive
Trans golgi is where
proteins, lipids and polysaccharides leave
What factory is the golgi
two things it processes
polysaccharide factory
- synthesis of glycolipids and sphingolipids
- processing of N-linked glycans on glycoproteins
How is secretion of some proteins regulated?
Vesicles containing the protein only fuse with the PM if a signal is released
Endocytic pathway
transports macromolecules from the external environment to the lysosomes/vacuoles for digestion
What kind of macromolecules are endocytosed?
- nutrients (proteins, cells…)
- signalling molecules
- pathogens
Two internalisation mechanisms
phagocytosis by engulfment
enodcytosis via small vesicles
Lysosomes
digestive organelle containing digestive enzymes
Endocytic pathway is increasingly…
acidified
Comparison of cellular digestion by prokaryotes and eukaryotes
Prokaryotes secrete enzymes and externally digest macromolecules before absorbing them.
Eukaryotes internally digest macromolecules by hydrolyses them in specialised hydrolytic compartments.
What kind of internalisation mechanism cannot happen with cell walls?
phagocytosis
percentage of cell volume that plant and fungal vacuoles make up
sometimes up to 90%
What do vacuoles provide
turgor pressure for cell growth
