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The most extensive component of the endomembrane system, in terms of membrane surface area, is/are the ...
a) plasma membrane
b) mitochondrial membranes
c) endoplasmic reticulum
d) nuclear envelope
e) Golgi apparatus
c) endoplasmic reticulum
If the ER signal sequence of a protein were deleted, the protein would end up ...
a) in the nucleus, because the nuclear pores are very large.
b) in the cytosol.
c) secreted from the cell by exocytosis.
d) in the Golgi apparatus, bypassing the ER.
e) randomly localizing to any organelle in the cell.
b) in the cytosol.
Gold nanoparticles below a certain size limit that are injected into the cytoplasm can later be observed in the nucleus. This is explained by which of the following:
a) There are gold-specific ion channels on the nuclear envelope.
b) Gold particles contain a nuclear localization signal.
c) The DNA requires gold to function effectively.
d) Molecules below a certain size can diffuse nonselectively through the nuclear pore complex.
e) Gold is recognized as valuable, and escorted into the nucleus by a nuclear transport receptor.
d) Molecules below a certain size can diffuse nonselectively through the nuclear pore complex.
Phosphofructokinase, a key enzyme in glycolysis, would ...
a) have an ER signal sequence.
b) have a nuclear localization sequence.
c) be translated into the ER lumen, undergo processing in the Golgi apparatus, then be shipped to its final location via transport vesicles.
d) have no localization sequence.
e) both a and c
d) have no localization sequence.
In a eukaryotic cell, RNA polymerase enzymes are synthesized in the _____.
a) cytosol, by free ribosomes
b) ER, by bound ribosomes
c) Golgi apparatus
d) nucleus
e) in mitochondria, by mitochondrial ribosomes
a) cytosol, by free ribosomes
What would be the fate of the membrane associated with a vesicle that has just exocytosed its cargo?
a) It is degraded by cytosolic enzymes and its constituents are recycled by the cell.
b) The empty vesicle fuses with a lysosome, which then degrades it.
c) The entire vesicle is exocytosed, such that the membrane components enter the extracellular fluid.
d) During exocytosis, the vesicle membrane fuses with the plasma membrane and becomes part of it.
e) The empty vesicle goes back to the Golgi apparatus to pick up another load.
d) During exocytosis, the vesicle membrane fuses with the plasma membrane and becomes part of it.
The carbohydrate groups found on the extracellular surface of the plasma membranes were 'installed' by cellular machinery ...
a) in the cytosol.
b) on the luminal side of the ER and Golgi membranes.
c) on the cytosolic side of the ER and Golgi membranes.
d) on the luminal side of the ER membrane and the cytosolic side of the Golgi membrane.
e) on the cytosolic side of the ER membrane and the luminal side of the Golgi membrane.
b) on the luminal side of the ER and Golgi membranes.
A transmembrane protein destined for the plasma membrane protrudes from the cytosolic face of the ER membrane. On its journey to its destination, where would you expect the protein to protrude?
a) on the non-cytosolic face of the Golgi, and on the extracellular face of the plasma membrane
b) on the cytosolic face of the Golgi, and on the cytosolic face of the plasma membrane
c) on the non-cytosolic face of the Golgi, and on the cytosolic face of the plasma membrane
d) on the cytosolic face of the Golgi, and on the extracellular face of the plasma membrane
e) I have absolutely no idea.
b) on the cytosolic face of the Golgi, and on the cytosolic face of the plasma membrane
