Biology Unit 2- chapter 7 Flashcards
What is protein trafficking?
How organelle proteins get to and into the correct organelle.
What are the three things needed for protein trafficking?
- A molecular “address” on the protein.
- A system that can recognize the address.
- A way to get the protein across the membrane.
In the nucleus, where are the proteins made and where are they going?
Made in the cytosol (cytoplasm) going into the nucleus.
What does the NLS stand for and what is the purpose?
Nuclear localization signal; contains “address”, 17-chain amino acid
5 steps for nuclear transport
- NLS- Protein attacks to importin
- importin helps protein across nucleus.
- protein-importin binds to Ran-GTP
- protein stays in nucleus, Ran-GTP and importin move to cytoplasm
- GTP is hydrolyzed to GDP.
what is importin’s purpose?
helps protein get across membrane in nuclear transport.
what does Ran-GTP do?
unbinds the importin from the protein
what does Ran-GTP hydrolyze to?
GDP (diphosphate)
Is protein folded or unfolded when being imported into the nucleus?
folded
Is protein folded or unfolded when entering the endomembrane system?
unfolded
RAN is a _ protein. Meaning?
G: it can change its shape/ structure to perform different tasks
what is the ER signal sequence?
contains the “address” for the secretory pathway.
other word for endomembrane system
secretory system
Steps for the Signal Hypothesis process
- ER sequence is synthesized by ribosome.
- ER signal sequence binds to SRP.
- SRP binds to receptor that is near the translocon.
- SRP gets released
- protein enters through the translocon
- ER signal sequence is removed
- ribosome detaches from translocon protein folding occurs
in the signal hypothesis process where is protein made and going into?
made in the cytosol (cytoplasm) going into the Lumen of the Rough ER to start
ribosome is made up of (2 things)
protein and RNA; it is the site for protein synthesis
in the ER signal sequence where the “address” on the amino acid sequence?
n-terminus
what is the SRP? and what does it do?
Signal Recognition particle binds to ER signal Sequence, temporarily stops protein synthesis
what is the translocon?
allows protein to get across the membrane.
endomembrane system/ secretory pathway order
lumen of rough ER, transport vesicle, cis face of Golgi apparatus, trans face of Golgi apparatus, transport vesicle, plasma membrane
where are the two points of sorting for the proteins in the endomembrane system?
- protein entering the rough ER
- trans face of the Golgi apparatus (making sure the protein gets into the correct transport vesicle)
what did the pulse-chase experiment do?
gave a function to the Golgi apparatus.
three types of major cytoskeleton filaments.
- actin filaments
- microtubules
- intermediate filaments
what is the cytoskeleton
gives the cell shape and aids in movement and transport of materials within the cell
