Exam 2 Part 6 Flashcards
In addition to DNA rep, cell division involves…
organelle division which sort themselves into daughter cells
membranes from nucleus, ER, and Golgi break down and then reform
Transport proper proteins to newly formed organelles
use an existing protein to move
-signalling
transport mechanisms
- transport through nuclear pores
- transport across membranes
- transport by vesicle
how does a protein know where to go?
signal sequences - particular characteristic of the amino acids helps
transport necessities
- need to mark/ID the protein
- mark its destination
How do we know where a specific signal sequence goes?
need to see things, so add florcesent mark to both the sequence and the predicted organelle
what goes into the nuclear envelope?
histones, DNA pol, helicase, topoisomerase, transcription machinery (regulatory), cytoskeleton
what goes out of the nuclear pore?
mRNA, ribozymes, ribosomes (assembled in nucleus)
histones
needed during replication, can diffuse through the smaller nuclear pores
nuclear lamina
filaments, hold and support the nuclear envelope
nuclear envelope
continuous with the ER membrane, has pores
nuclear pores
big cages, docking system
how big molecules get into the nucleus
small enough for selectivity, big enough for some passivity
Ran-GDP
binds to nuclear protein and receptor to allow the protein into the nucleus.
GTP will replace GDP in the nucleus
Ran-GTP
GTP replaces GDP on Ran-GDP, which kicks off the cargo protein (STAYS WITH RECEPTOR)
Passes back out of the nuclear membrane with the receptor
hydrolyzes its bound GTP and GDP disassociates from receptor
G-proteins
bind to guanine nucleotides (GDP, GTP)
hydrolyze GDP to GTP
act like “switches” by ossilating bt 2 guanine binding
transport into nuclear envelope
Ran-GDP binds to protein, with binds to receptor. Complex changes shape and enables it to enter membrane
Ran-GTP replaces Ran-GDP and kicks off protein
Ran-GTP and receptor travel back across membrane
Ran hydrolyzes its GTP and Ran-GDP dissociates from receptor
transport into organelles
either can go into the lumen because that’s where it’s job is or into the membrane for transport elsewhere (control when and where)
import into ER
ribosomes are brought near the ER membrane so that the protein can be threaded through while synthesis occurs
SRP
signal recognition particle
binds to proteins that will take it to the membrane
hydrophobic start-transfer sequence
hydrophobic so that it will embed into the membrane
signal peptidase
cuts off the start-transfer sequence if it is at the N-terminus
stop-transfer sequence
enters channel and stops the transfer of the protein into the membrane – for transmembrane proteins
chaperone proteins
regulate the proper folding of proteins in the ER
mitochondrial transport
protein created, folded in cytosol, then taken to mitochondira, unfolded as it binds to receptor, transported across both membranes, and then folded again
