Bio344-Exam#1 (Q's & A's) Flashcards
In order to maintain osmotic balance and maintain cell volume, what would the Na+/K+ pump do if the cell is exposed to pure water?
Start pumping faster because 3 ions are pumped out for two that come in and the cell needs to get rid of as many ions as possible.
How are glucose transporters distributed around an intestinal epithelial cell, which is a conduit for glucose into the rest of the body?
Active transporters take up glucose into the cell from the intestine and passive transporters move the glucose from the cell into the extracellular fluid
What process below will be facilitated by active transport?
Movement of glucose into an intestinal epithelial cell.
The Na+/K+ pump is a
antiport
What molecule contributes to the negative charge on the cytosolic side of the membrane?
phosphatidyl serine
What gives a cell its strength and its shape?
the cytoskeleton.
How can ABC transporters interfere with cancer treamtent?
by Pumping chemotherapy durgs out of cancer cells
What is the function of a dendrite on a nerve cell?
They receive signals from the axon terminals of other nerve cells
What causes the kink in one of the phospholipids fatty acid tails?
a cis double bond.
Why do phospholipids in water spontaneously organize into spheres?
So the fatty acids do not have to associate with water
Where are the glycolipids in an animal cell?
On the extracellular side of plasma membranes
What is the primary function of membranes?
They are a barrier to polar and charged molecules
What energy source is used to transport glucose from inside an intestinal epithelial cell to the outside?
glucose is exported passively from intestinal epithelial cells and therefore no energy source is required.
If K+ ions rush out of a cell what will happen to the electrochemical gradient of Na+ in an animal cell?
The electrochemical gradient will increase promoting transport of Na+ across the membrane.
Which molecule below is polar?
H2O
What does it mean if during a FRAP (Fluorescenc Recovery After Photobleaching) experiment the bleached area rapidly regains fluorescence?
That the fluorescent protein is moving rapidly in the membrane
What is an important property of a phospholipid?
It is a molecule that is polar on one end and nonpolar on the other end.
How can a protein be removed from a membrane?
By rupturing and dissolving the membrane with a detergent.
How are ion channels, that are the first to open, gated in muscle cells at the neuromuscular junction?
by neurotransmitters
What is the anion transporter in red blood cells used for?
It removes CO2 from the body in the form of HCO3-.
What is a synaptic cleft?
It is the space between the axon terminal of a nerve cell and neighboring muscle or nerve cells.
Why does an action potential not move backwards towards the dendrites of a nerve cell?
Because the membrane potential is restored when an ion channel is inactivated so that after inactivation the channel remains closed
How are sodium channels that allow an action potential to travel along the axon of a nerve cell gated?
voltage
Which of the molecules below will cross the lipid bilayer, without the aid of a protein, fastest?
O2
Why does one of the fatty acid chains in a phospholipid have a kink?
The kink gives the phospho lipid the shape of a sphere so that it forms sheets instead of micelles.
What would a large positive peak on a hydropathy plot signify?
That the protein is likely to have a membrane spanning region
How is a lipid raft different from the rest of the membrane?
It is enriched in sphingomyelin.
In a human cell, most of the phospholipids are usually part of which membrane?
the membrane of the Endoplasmic Reticulum.
Where does the energy to transport glucose into a cell against the glucose concentration gradient come from?
Na+ gradient
How many Na+ ions does the Na+/K+ pump transport during each cycle?
3
What happens to the membrane potential when a potassium leak channel opens up during an action potential?
The membrane potential will be restored with a negative charge on the cytosolic layer of the membrane.
What are the four parts of phosphotidyl choline?
choline, phosphate, glycerol, and fatty acids.
What is a neurotransmitter?
It is a ligand than can bind ion channels.
What is a difference between active transport and passive transport?
Passive transport goes from high concentration to low concentration while active transport goes from low concentration to high concentration
Why can a sodium ion not pass through a potassium leak channel?
The sodium ion cannot interact correctly with the oxygen atoms of the selectivity filter of the potassium leak channel.
What kind of ATP driven pump is the Na+/K+ pump?
P-type pump
What is acetyl choline?
ATP
What is the energy source for the Na+/K+ pump?
ATP
How could one test if sodium ions can pass through a lipid bi-layer without the aid of proteins?
By testing if sodium ions can enter liposomes.
What does the influx of Ca2+ into an axon terminal cause?
It causes synaptic vesicles to fuse with the membrane.
The Na+/glucose transporter is a?
symport
What is a property of the membrane spanning region of a membrane protein?
It contains amino acids with non-polar side chains.
What is a characteristic of axon terminals on a nerve cell?
They contain vescicles with neurotransmitters
How do most proteins span the membrane?
In the form of alpha-helices.
What is Sodium Dodecyl Sulfate?
detergent
What process below is facilitated by a channel protein?
Transport of Na+ ions into the cell
What is the consistency of the phospholipid bilayer?
fluid
How can proteins move in the membrane?
Proteins diffuse laterally in the membrane.
Which of the following ions is present in high concentration in the cytosol but at low concentrations extracellularly?
K+
Most membrane proteins in a human red blood cell are…
Associated with the cytoskeleton
