pack Flashcards
What do free ribosomes synthesize?
Proteins that stay inside the cytoplasm
What do ribosomes bound to the rER synthesize?
Proteins that leave the cell and go to the cell membrane (bc they leave their house and they go to the ER)
Where does translation always start?
On free ribosomes
What is the endomembrane system for?
Anything going inside, outside or to the membrane
What are the components of the
endomembrane system?
RER, golgi apparatus, endosomes, secretory vesicles, and lysosomes
What are endosomes? What is their function?
They are: vesicles
Function: Transport from the golgi or inside or outside the cell
Where is the signal to send the proteins to the rER attached? Is it Hydrophobic or hydrophilic?
Attached: At N terminus (start)
Hydrophobic (bc it wants to get as far away from the water (ECF) as it can so it goes to the ER )
How does the taking the protein to the rER take place?
Translation starts in free ribosome
Signal recognition particle binds to signal
SRP stops translation
SRP takes the protein
SRP binds to SRP receptor on the ER
Both hydrolize GTP which causes the SRP to deattach from the protein and causes the
Transcolon channel to open and the ribosome to get pushed in
As the protein enters the organelle, the signal is cleaved by signal peptidase
Translation is resumed in the ER
What is translocon?
a channel that opens from hydrolization of GTP from the SRP complex to let ribosome in
What is signal peptidase?
Removes the signal from the protein
What is a glycoprotein?
Sugar + protein
Where does N-linked glycosylation take place?
Select asparagine in rER
(N in er bc N is before O in alphabet) (bc you sparing engine)
Where does O-linked glycosylation take place?
In golgi on serine and theronine
(to show serine) (bc it is a theory that you have that might work)
What is the sugar that is added to both O and N glycosylation
O: N-acetylgalactosamine
(bc women are lactose intolrent)
N: N-acytelglucosamine
Does N&O glycosylation happen before or after folding?
N: before
O: after
What process in collagen modification requires vitamin C?
Hydroxylation
(bc you get hydrated when you drink vitamin C)
What happens when there is a problem in forming the triple helix in glycosylation?
osteogensis imperfecta
(the triple helix looks like candy which contain “glycogen”)
(if that candy is bad “expired” it will cause further bone problems)
What enzyme does the cross linking?
lysyl oxidase
(Ly and Ly are linked by s
and oxygen is linked to everything)
What is the disease caused by problems with cross-linking?
meneks disease
What does lysyl oxidase require?
Copper
(bc the chain linking the ly which is made of copper oxidizes easily)
How does a protein get to the nucleus?
Protein has nuclear localization signal (ticket)
Protein with NLS binds to importin (Nucleur import receptor NIR)
Importin takes is through the nuclear pore
Ran-GTP binds to importin which releases the protein inside the nucleus
Ran-GTP bound to importin leaves the nucleus
Ran-GTP hydrolizes to Ran-GDP which releases the importin outside the nucleus
How do proteins get translocated into the mitochondria? Where do those proteins get synthesized? Does it require ATP?
Synthesized: In free ribosomes in cytosol
The protein binds to receptors on the mitochondria, TOM takes it through the outer membrane, while TIM takes it through the inner membrane
Requires ATP
How do proteins get translocated into the mitochondria in more detail?
Protein that is bound to HSP70 inserts its signal to receptor of TOM
TOM takes it inside the outer membrane, atp is hydrolized to remove HSP70
Protein binds to TIM and electrical gradient pulls it inside.
The protein binds to HSP70 again and uses ATP to pull the rest of the protein inside.
What phosphorylates mannose in lysosomal proteins in the golgi?
N-acetylglucosamine-1-phosphotransferase.
(its diff bc its not norm to have lyse)
