Bio344-Exam#2 (Q's & A's) Flashcards
What enzyme does cAMP activate?
protein kinase A
How can glucose transporters be inserted rapidly into the cell membrane after the cell detects insulin?
Glucose transporters are present in recycling endosomes which can fuse with the plasma membrane rapidly.
How do enzymes end up in the late endosome?
from the ER they go to the Golgi then the late endosome
How does a protein get directed to a specific cellular address?
The correct target has a receptor that binds the signal sequence of the protein.
Where is the signal recognition particle receptor located in the cell?
the ER membrane
What signal can activate a Jak-Stat pathway?
Interferon
What is autocrine signaling?
Occurs when a cell releases a signal and expresses a receptor for that signal at the same time.
Which of the following is true of the mitochondrial signal sequence?
it forms an alpha helix with one charged side while the other side is non-polar.
How do proteins get transported from the cytosol to the endoplasmic reticulum?
Transmembrane transport
What is a difference between an early endosome and a late endosome?
Endocytosed receptors are recycled from the early endosome and not the late endosome.
How can a mutation in dynamin lead to paralysis in fruit flies?
New synaptic vesicles can no longer be made because phospholipids are not recycled from the cell membrane
The Jak-STAT pathway is an example of…
enzyme linked receptor signaling pathway
Which is a difference between the cis and trans face of the Golgi apparatus?
Enzymatic reactions that occur in the cis face are different from those present in the trans face.
What does a kinase do?
it adds phosphate groups to proteins
Why are the Golgi in goblet cells in the small intestine not homogeneously distributed throughout the cell?
These cells release mucus which is only released from one end of the cell.
What are start and stop transfer sequences?
They are membrane spanning regions that determine how a protein is inserted into the ER membrane.
What happens to cargo after it has arrived at an early endosome?
it is sent to the late endosome
Where does the signaling molecule nitric oxide come from?
It is generated from arginine by an enzyme
Where are sugars first added to proteins?
Endoplasmic reticulum.
What is a difference between the early endosome and the late endosome?
The late endosome has proton transporters in its membrane while the early endosome does not
What is a function of a protein coat in vesicular transport?
It aids in bending the membrane and forming the transport vesicle.
Why does invagination happen in multivesicular bodies that form between early and late endosomes?
So that membrane proteins can be degraded completely.
What does a G-protein linked receptor do when it binds a signal?
It replaces the GDP of a G protein with GTP.
What molecule provides the energy to actively transport proteins from the cytosol into the nucleus?
Ran-GTP
Which receptor binds antibodies?
the Fc receptor
What enzyme makes cAMP?
adenylyl cyclase
Why is a phospholipid exchange protein needed to transfer phospholipids to the mitochondria?
Because there is no vesicular traffic to mitochondria to deliver phospholipids.
What is the content of secretory vesicles that wait near the plasma membranes of beta cells in the pancreas?
insulin
What kind of protein coat is present on vesicles transporting cargo from the cell membrane to an early endosome?
Clathrin
What is a low density lipoprotein particle?
It is a protein that delivers cholesteryl esters to cells
What is likely to happen to a receptor, such as the LDL receptor, once it has delivered its cargo?
It is recycled back to the cell membrane.
What kind of N-linked oligosaccharides are generated in the Golgi apparatus?
complex oligosaccharides
What is a function of the Golgi Apparatus?
This is where the original oligosaccharide precursor is modified
How do cells take up the correct substrates in endocytosis?
A receptor, specific for the substrate, will concentrate it into endocytic vesicles.
What type of filament is used to move multivesicular tubular clusters?
microtubules
What is a domain present on a nuclear receptor that binds steroid hormones?
A DNA binding domain
Where is there a reservoir of calcium inside the cell?
Endoplasmic Reticulum
Which below is an important class of cell surface receptors?
G-protein linked receptors
What is a difference between a G-protein linked receptor and an enzyme linked receptor?
The enzyme linked receptor phosphorylates itself and can phosphorylate other proteins; the G protein linked receptor cannot.
What would be the consequence of a mutant low-density lipoprotein particle receptor that does not bind to adaptin?
More LDL particles in the blood stream.
Where are phospholipids made in the cell?
In the cytosolic layer of the smooth ER membrane.
How are proteins often activated in signaling pathways?
they are phosphorylated.
How do cargo vesicles fuse with the membrane of the target compartment?
SNARE proteins bring the membranes of the vesicle and target compartment close together so they can fuse.
What does a mast cell do?
It releases histamines
What kind of protein coat is present on vesicles transporting proteins from the ER to the Golgi?
COP II
What signal tag is required to send a protein to the lysosome?
Mannose 6 phosphate
Which organelle is responsible for carbohydrate synthesis?
Golgi apparatus
Where are G-proteins located inside the cell?
on the cytoplasmic face of the plasma membrane
What is the form of intercellular signaling that involves hormones called?
endocrine signaling
Insulin binds to:
an enzyme linked receptor
