Vesicles N Stuff Flashcards
What did George Palade’s pulse-chase experiment discover?
The secretory pathway going from ER->Golgi->Out of cell
What is a pulse chase experiment?
Pulse - adding radio labeled RNA or amino acids
Chase - after adding pulse seeing where the labels go over time
Do proteins go to the ER before, after, or during translation?
During
What is puromycin?
An antibiotic that causes ribosomes to stop translating
What was the original signal hypothesis?
Both free ribosomes and those in the ER are the same just what they make is different and that there was a signal in the N-terminus
What is the revised signal hypothesis?
mRNA has a sequence for the signal and is recognized by the ER membrane allowing it to enter, the signal is cleaved inside the ER and the fully translated protein slowly goes into the ER membrane
Describe the full process of the protein ending up in the ER lumen
- signal recognition particle recognizes signal sequence and binds to it
- SRP receptor in the ER membrane binds to SRP-ribosome thing
- SRP receptor puts complex w the translocator
- the new protein passes through the translocator and enter ER lumen
What is the signal sequence cleaved by?
Signal peptidase
What are the steps of entry of a soluble protein?
- enter translocator
- single peptidase removes the signal
- protein passes through translocator
- signal stays in ER membrane
How are transmembrane proteins integrated into the ER membrane?
- same steps as soluble protein
- changes once a stop transfer sequence (hydrophobic) in the protein stays in the membrane
Which destinations use gated transport, transmembrane transport, and vesicular transport from the cytosol?
Nucleus - gated
Peroxisomes, mitochondria, plastids, ER - transmembrane
Everything else - vesicular
What is an LDL?
Low density lipoprotein
How is cholesterol made?
A feedback system
What does a FH homozygote cause?
Can create LDL but can’t uptake it due to LDL receptors not being bunched up
What happens to LDL when it comes into the cell?
Internalized, degreased by lysosomes and releases cholesterol
