76 Questions
What is directly responsible for the function of carriers in primary active transport?
The hydrolysis of ATP
What is the source of energy for the 'uphill' movement of molecules in secondary active transport?
Downhill transport of Na+ into the cell
Which type of transport involves the simultaneous movement of Glucose and Na+ in kidney and intestine lumens?
Cotransport/Symport
Primary active transport requires the hydrolysis of ATP for the function of carriers
True
Secondary active transport obtains energy for 'uphill' movement from the 'downhill' transport of Na into the cell
True
Example of secondary active transport includes the simultaneous movement of glucose and Na+ in kidney and intestine lumens
True
What is uniport in transport?
Transport of only one molecule without coupling to the transport of another molecule or ion
What characterizes symport in transport?
Two different molecules can move through a membrane in the same direction using a common carrier mechanism
What defines antiport in transport?
Two different molecules can move through a membrane in opposite directions
What characterizes primary active transport?
Hydrolysis of ATP is directly responsible for the carrier protein function
In primary active transport, what activates the pump?
Phosphorylation using a P i from ATP
What is the role of the transport protein in primary active transport?
It is an ATPase enzyme that hydrolyzes ATP
Where is the Ca+2 Pump located?
On all cells' plasma membrane and in the endoplasmic reticulum of striated muscle cells
What does the Ca+2 Pump do?
Removes Ca+2 from the cytoplasm by pumping it into the extracellular fluid or cisternae of the ER
What is one of the functions of the Ca+2 Pump?
Aids in release of neurotransmitters in neurons and in muscle contraction
Is the Ca+2 Pump located on all cells PM and in the endoplasmic reticulum (ER) of striated muscle cells?
True
Does the Ca+2 Pump remove Ca+2 from the cytoplasm by pumping it into the extracellular fluid or cisternae of the ER?
True
Does the Ca+2 Pump aid in the release of neurotransmitters in neurons and in muscle contraction?
True
What does the Na+/K+ Pump do?
Pumps 3Na+ out of the cell and 2K+ into the cell
What is one of the functions of the steep Na and K gradient created by the Na+/K+ Pump?
Provides energy for coupled transport of other molecules
Where does the Na+/K+ Pump function?
Found in all body cells
Is the Na+/K+ Pump found in all body cells?
True
Does the Na+/K+ Pump use ATPase enzyme to pump 3 Na+ out of the cell and 2 K+ into the cell?
True
Does the steep gradient of Na and K across the plasma membrane serve to maintain osmolality?
True
What is the source of indirect energy for the co-transport of Na and glucose in secondary active transport?
ATP from the Na+/K+ATPase pumps
What is the primary function of the carrier protein in secondary active transport?
Simultaneously transport Na and glucose into epithelial cells
What is required to maintain a lower intracellular concentration of Na in secondary active transport?
Action of Na+/K+ATPase pumps
Secondary active transport moves Na and glucose from the lumen of the intestine and kidney tubules into the lining epithelial cells
True
The co-transport of Na and glucose requires a lower intracellular concentration of Na
True
The co-transport of Na and glucose in secondary active transport depends indirectly on ATP
True
What is the process that involves the fusion of a vesicle with the plasma membrane for the secretion of large molecules?
Exocytosis
What is required for the movement of large molecules like cholesterol into the cell?
Endocytosis
What is involved in the process that requires ATP for movement of large molecules?
Exocytosis
What causes the unequal distribution of charge across the plasma membrane?
Permeability properties of the plasma membrane
What is the primary factor contributing to the negative charge inside the cell compared to the outside?
Cellular proteins and phosphate groups of ATP
What term is used to describe the difference in charge across the plasma membrane?
Potential difference
Is there an unequal distribution of charge across the plasma membrane due to the permeability properties of the plasma membrane?
True
Does the potential difference make the inside of the cell negative compared to the outside?
True
Are cellular proteins, phosphate groups of ATP, and other organic molecules negatively charged at the pH of the cell cytoplasm?
True
What is the primary role of fixed anions within the cell?
Attract positively charged inorganic ions from the extracellular fluid
Which inorganic cations are mainly influenced by the fixed anions within the cell?
K+, Na+, and Ca+2
Why are negative ions (anions) fixed within the cell?
They cannot penetrate the plasma membrane
Why does K+ accumulate at high concentrations in the cell?
The Na+/K+ pumps actively bring in K+
What contributes to the negative charge inside the cell compared to the outside?
Negative anions inside the cell attracting cations outside the cell
What is the intracellular concentration of K+ compared to the extracellular concentration?
150 mEq/L inside and 5 mEq/L outside
K+ accumulates at high concentrations in the cell because the membrane is very permeable to K
False
The Na+/K+ pumps actively bring in K
False
The K concentration inside is 150 mEq /L and out is 5 mEq /L
True
What contributes to the negative charge inside the cell compared to the outside?
The high permeability of the membrane to K+ ions
What is the primary role of fixed anions within the cell?
Contributing to the negative charge inside the cell
Why does K+ accumulate at high concentrations in the cell?
Due to the high permeability of the membrane to K+ ions
What is the equilibrium potential (E K ) for K+?
90 mV, meaning the inside has a voltage 90 mV lower than the outside
What is the equilibrium potential (E K ) for K+?
90 mV
What does the equilibrium potential (E K ) of K+ indicate?
The inside has a voltage 90 mV lower than the outside
What characterizes the state of equilibrium for K+?
More K inside than outside
What determines the resting membrane potential of a cell?
The ratio of the concentrations of each ion on either side of the membrane
If the plasma membrane were only permeable to Na+, what would be the resting membrane potential?
+66 mV
If the plasma membrane were only permeable to K+, what would be the resting membrane potential?
-90 mV
What contributes to the resting membrane potential (RMP) of a cell?
The concentration of ions and the permeability of the membrane to those ions
What is the typical range for the resting potential in most cells?
Between -65 mV and -85 mV
What happens to the membrane potential when a neuron sends an impulse?
The permeability of Na+ increases, driving the membrane potential closer to the equilibrium potential for Na+
What contributes to the actual resting membrane potential not being as negative as the K equilibrium potential?
Diffusion of Na into the cell
What is indicated by the dashed lines in relation to the resting membrane potential?
Some K diffusing out of the cell
What results in the resting membrane potential not being as negative as the K equilibrium potential?
Diffusion of Na into the cell
What is the primary function of the Na+/K+ pump?
To transport 2 K+ in for every 3 Na+ out to maintain the voltage difference
What contributes to the negative intracellular charge maintained by the Na+/K+ pump?
The electrogenic effect of the pump
What is the role of the Na+/K+ pump in maintaining the resting potential and concentration differences?
It acts to counter K+ and Na+ leaking out at the resting potential
What type of channels does K have?
Voltage gated and not gated
When do voltage gated K channels open?
When a particular membrane potential is reached
What type of channels does Na have?
Closed at rest, voltage gated
What happens to the Voltage Gated Na Channels at rest?
They are closed
What membrane potential depolarization triggers the opening of Voltage Gated Na Channels?
-55 mV
What happens as the membrane potential climbs toward sodium equilibrium potential?
The Na channels close
What happens at around 30 mV in voltage gated K channels?
K rushes out of the cell following the electrochemical gradient
What is the effect of voltage gated K channels opening at around 30 mV?
The cell repolarizes back toward the potassium equilibrium potential
What is the membrane potential change associated with voltage gated K channels opening?
-70 mV to a more negative value
Test your knowledge of active transport mechanisms, including primary and secondary active transport, and their associated carrier functions. Explore examples such as Ca+2 pump, H+ pump, Na+/K+ ATPase, and cotransport/symport and countertransport/antiport systems.
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