lecture 7 ( Intracellular Compartments and Protein Transport) Flashcards
Where did the mitochondria and the choloroplast evolve from?
when an aerobic prokaryote was engulfed by a larger pre-eukaryotic cell.
what is the main function of the cytosol?
contains metabolic pathways. Protein synthesis. cytoskeleton (protein filements)
what is the main function of the Nucleus?
contains genome (DNA and RNA synthesis)
what is the main function of the Endoplasmatic Reticulum?
synthesis lipids and protein
what is the main function of the golgi apparatus?
modifications, sorting, and packing of proteins and lipids for secretion (production) or delievery to another orgenelle
what is the main function of the lysosomes?
intercellular degradation
what is the main function of the Endosomes?
sorting of endocytosed material
what is the main function of the mitochondria?
ATP synthesis by oxidative phosphorylation
what is the main function of the chloroplasts?
ATP synthesis by photosynthesis
what is the main function of the peroxisomes?
oxidation of toxic molecules
where protein synthesis occurs mostly?
on the ribosome
How proteins are transported to organelles?
by signals that direact the protein to the desired organelle
what happens to the proteins that lack signals?
they remain in the cytosol
what is the function of the nuclear pore?
selective gates that actively transport specfic molecules
transportation machanism when protein moves from the cytosol into the nucleus:
transported through nuclear pores
Transportation mechanism of protein moving from cytosol into ER, mitochondria, peroxisom, and chloroplast:
transported across the organelle membrane by protein translocators located in the membrane. The protein must unfold to snake through the translocator.
transportation mechanism of the proteins moving from the ER to other compartments:
transported to different destination by vesicles
what is the function of the signal sequence?
it direct the proteins to correct destination
what is typical sorting signal?
is a continuous stretch of amino acids (15-60) amino acid long. the signal sequnce is often removed once the proteins go to their destination.
can signals be removed or added to cytosolic protein?
yes, the adding and deleting signal will cause different transportation of different protein
what does the inner membrane contain?
it contains some proteints that provide space (anchorge) for the nuclear lamina
what is the lamina?
a network of protein filaments that line the inner face of the membrane (inner)
How many proteins contained in the nuclear pores?
30 different proteins
True or False: large, non-soluble molecules can pass freely into the nulceus.
False, only small water-soluble molecules can pass freely and non selectively into the nucleus and that is because of the proteins that line the nuclear pores. They form a soft segments that fills the center of the pore.
How does Large molecules such as proteins pass through the nuclear pores?
these large protein display nuclear localisation signal which is a short sequence of positively charged lysine or arginine…
how does the nuclear pores transports to the inside of the nucleus?
1) cytosolic protein import receptor to interact with the nuclear localisation sequence.
2) then the nuclear import receptors moves with the short amino acids in the central region and into the nucleaus
3) Ran-GTP binds to the receptor and deattch the protein which is delivered to the nucleus
4) Ran-GTP dissociate from the receptor in the cytosol by hydrolysing itself into Ran-GDP, this froms phosphorus iodide.
What is the receptor function?
it helps direct a newly synthesised protein to the pores by interacting with the cytosolic fibers in the cytosol.
True or False: The nuclear import receptor deliever the protein and return to the cytosol
TRUE
