Topic 4, Lecture 1 Flashcards
List the types of protein transport.
Gated transport, transmembrane transport, vesicular transport, and engulfment
Which organelles use gated transport?
Nucleus
Which organelles use transmembrane transport?
Plastids, mitochondria, peroxisomes, endoplasmic reticulum
Describe gated transport.
Gated transport only occurs in the nucleus. Gated transport requires the use of a large pore to accommodate folded proteins.
Describe transmembrane transport.
Transmembrane transport is transport from cytosol across a membrane into an organelle.
Describe vesicular transport.
Protein resides in an organelle and moves to another organelle.
We can describe signaling sequences as _______ and _________.
Necessary and Sufficient
When analyzing signaling sequences it is important to pay attention to…
Length, Nature, Distance, Location
What does it mean for a signaling sequence to be closer to the amino or carboxy termini?
If a signaling sequence is closer to either end of the polypeptide, it makes it easier to cleave after transport.
What does it mean for a signaling sequence to be in the middle of a polypeptide?
The signaling sequence contributes to the permanent three-dimensional structure of the polypeptide and cannot be cleaved after transport.
What is the relation between the nucleus and the endoplasmic reticulum?
The nuclear membrane is continuous with the endoplasmic reticulum.
Which organelles have a double membrane?
Nucleus and Mitochondria
How many phospholipid layers correspond to double membranes?
Four phospholipid layers are equivalent to a double membrane
What are the unique characteristics of the nuclear membrane?
It is punctuated with pores and lined with a cytoskeletal lamina.
What is the difference between the nuclear pore and the nuclear pore complex?
The nuclear pore is just the opening but the nuclear pore complex is the opening and all\ of its associated proteins.
What do we refer to the cytoskeletal lamina as when it is on the nuclear membrane?
Nuclear lamina
What does the nuclear lamina look like?
Gauze glued to the inside
Give a basic description of the nuclear pore complex.
The nuclear pore complex is a bunch of proteins that act like a gate at the nuclear pore.
Describe the morphology of the nuclear pore complex.
The nuclear pore complex has an octagonal structure that extends down into the nucleus that is tied together to create a basket on the inside. Long filaments extend into the nucleoplasm in a terminal ring called the nuclear basket.
How many Daltons is the nuclear pore complex?
66 million daltons
What are proteins referred to as when they belong to the nuclear pore complex?
Porins
How long are the filaments that extend into the nucleoplasm?
8-100 nanometers
What is the most important aspect in the selective nature of the NPC?
The nuclear pore complex has FG nuceloporins.
Describe FG nucleoporins.
FG nucleoporins are hydrophobic repeats made of phenylalanine and glycine that stick together and to other nonpolar molecules and serve as binding sites to the beta subunits for the importin receptor.
