Flashcards (2)
(24 cards)
what is Active Transporthy is it importantant?
Active transport is a cellular process that moves molecules against their concentration gradient, from areas of lower concentration to areas of higher concentration. This process requires energy, typically in the form of ATP, to function. Active transport is vital for maintaining cellular concentrations of ions and nutrients, allowing cells to regulate their internal environment and perform necessary functions.
what is a Primary Active Transport?give an example?why is it important?
Primary active transport is a mechanism that directly uses energy, typically from ATP hydrolysis, to move ions or molecules across a cell membrane against their concentration gradient. A well-known example is the Na/K ATPase, which pumps sodium out of and potassium into cells, crucial for maintaining membrane potential and cellular function.
what is Na/K ATPase?found in?what does it do and how? how is it inhibited?
The Na/K ATPase is an essential enzyme in mammalian cells that maintains the electrochemical gradient by pumping three sodium ions out of the cell and two potassium ions in, using ATP as the energy source. This process is electrogenic, contributing to the membrane potential. It is inhibited by substances like vanadate and digoxin, which can affect cellular functions.
what is Secondary Active Transport?how does it transport other substances?
Secondary active transport is a type of transport that does not directly use(energy source) ATP but relies on the energy created by primary active transport processes. It utilizes the electrochemical gradients established by primary transporters to move other substances across the membrane. This can be symport (same direction) or antiport (opposite direction) and is vital for nutrient uptake and ion balance.
what is a proton pump?how Proton Pump generated ATP?
A proton pump is a type of transport protein that moves protons (H+ ions) across a membrane, creating a proton gradient. In mitochondria, the proton pump is crucial for ATP production, as it uses the energy from NADH reduction to drive protons out of the mitochondrial matrix, which then flow back in through ATP synthase to generate ATP.
what is the Mitochondrial Electron Transport Chain,where is it located?what does this process do?
The mitochondrial electron transport chain is a series of protein complexes located in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen. This process releases energy, which is used to pump protons into the intermembrane space, creating a proton gradient that drives ATP synthesis through chemiosmosis.
what is ATP Hydrolysis?what is it utilised for?
ATP hydrolysis is the chemical reaction in which adenosine triphosphate (ATP) is broken down into adenosine diphosphate (ADP) and inorganic phosphate (Pi), releasing energy. This energy is utilized by various cellular processes, including active transport, muscle contraction, and biosynthesis, making ATP a crucial energy currency in biological systems.
what is Electrogenic Pump
An electrogenic pump is a type of transport protein that generates a voltage across a membrane by moving ions in unequal amounts. The Na/K ATPase is a prime example, as it pumps three sodium ions out of the cell for every two potassium ions it brings in, creating a net positive charge outside the cell, which is essential for maintaining membrane potential.
Conformational Change
Conformational change refers to the alteration in the shape of a protein that occurs upon binding of a substrate or ligand. In the case of the Na/K ATPase, the binding of sodium ions triggers a change from the E1 to E2 conformation, allowing the transport of ions across the membrane. This mechanism is crucial for the function of many transport proteins.
what is Phosphorylation
Phosphorylation is the addition of a phosphate group to a molecule, often a protein, which can alter its function and activity. In the context of the Na/K ATPase, ATP hydrolysis leads to the phosphorylation of the enzyme, which is essential for its conformational change and subsequent ion transport, highlighting the importance of this process in cellular signaling and metabolism.
E2 Ion Binding Site
The E2 ion binding site is characterized by its outward-facing orientation, which allows for high affinity for potassium ions (K+) and low affinity for sodium ions (Na+). This configuration facilitates the release of Na+ and the binding of K+, which is crucial for the function of the Na/K ATPase. The binding of K+ triggers the cleavage of inorganic phosphate (Pi), leading to a conformational change from E2 to E1, allowing K+ ions to be transported into the cell.
K+ Binding
K+ binding to the E2 state of the Na/K ATPase is a critical step in the transport cycle. When K+ binds, it triggers the cleavage of inorganic phosphate (Pi), which is a key event that leads to the transition from the E2 to the E1 state. This transition allows for the release of K+ into the intracellular space, effectively transporting potassium ions into the cell, which is essential for maintaining cellular homeostasis and function.
E1 to E2 Transition
The transition from the E1 to E2 state in the Na/K ATPase is a crucial part of its function. In the E1 state, the pump has a high affinity for Na+ ions, which are released outside the cell. Upon binding of K+ ions, the pump undergoes a conformational change to the E2 state, which has a high affinity for K+ and low affinity for Na+. This switch is essential for the proper functioning of the pump and the maintenance of ion gradients across the membrane.
what is the other name for gastric Hydrogen Potassium ATPase?and function
The gastric hydrogen potassium ATPase, also known as H+/K+ ATPase, is an enzyme that plays a vital role in acidifying the stomach. It actively transports hydrogen ions (H+) out of the gastric cells in exchange for potassium ions (K+). This process is crucial for the production of gastric acid, which aids in digestion and protects against pathogens. The proper functioning of this ATPase is essential for maintaining the acidic environment necessary for digestive enzymes to work effectively.
What are two examples of primary active transport?
Na+/K+ ATPase (in mammals).
H+/K+ ATPase (in mammals, acidifies the stomach).
What happens to K+ and Na+ if no energy is provided?
A: The concentrations equalize:
[K+] inside = [K+] outside.
[Na+] inside = [Na+] outside.
How does redox energy power the mitochondrial proton pump?
The mitochondrial electron transport chain uses the reduction energy of NADH to pump protons across the membrane.
How do proteins use light energy to make NADPH?
In photosynthesis, proteins use photon energy to create a proton gradient across the thylakoid membrane and generate reduction power as NADPH.
How does Na+/K+ ATPase maintain membrane potential?
It pumps 3 Na+ out and 2 K+ in, creating an electrochemical gradient (electrogenic process).
What inhibits Na+/K+ ATPase?
Vanadate and digoxin inhibit Na+/K+ ATPase.
How does ATP provide energy to molecules?
ATP phosphorylates proteins, transferring a phosphate group to activate or change their conformation.
Do metabolic inhibitors affect active transport?
Yes, they stop ATP production, which halts active transport since it requires energy.
What happens if you increase substrate concentration in active transport?
Initially increases the rate of transport, but it saturates at high concentrations when all transport proteins are occupied.
Explain the catalytic cycle of Na+/K+ ATPase.
The Na+/K+ ATPase alternates between two states, E1 and E2. In the E1 state, the binding sites face inside the cell and have a high affinity for Na+. Three Na+ ions bind, triggering ATP hydrolysis and phosphorylation of the pump. This causes a conformational change to the E2 state, where the binding sites face outside the cell. Na+ is released due to a lower affinity in this state. The E2 state has a high affinity for K+, so two K+ ions bind. This triggers the release of the phosphate group, returning the pump to the E1 state. K+ is then released inside the cell, restarting the cycle.
