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Questions and Answers
What primarily determines the movement of a nonpolar solute across a membrane?
What primarily determines the movement of a nonpolar solute across a membrane?
- Size of the molecule
- Electrochemical potential
- Concentration gradient (correct)
- Presence of transport proteins
What is the role of carrier proteins in facilitated diffusion?
What is the role of carrier proteins in facilitated diffusion?
- They generate electrochemical gradients.
- They create hydrophobic barriers.
- They form channels for ions to pass through.
- They bind solutes and undergo conformational changes. (correct)
Why do polar substances, particularly ions, have low permeability across membranes?
Why do polar substances, particularly ions, have low permeability across membranes?
- They associate with water molecules, forming hydration shells. (correct)
- They are too large to cross.
- They require specific energy inputs.
- They cannot form stable bonds with membrane lipids.
What keeps the concentration of glucose low inside animal cells?
What keeps the concentration of glucose low inside animal cells?
What characterizes facilitated diffusion as a transport process?
What characterizes facilitated diffusion as a transport process?
Which type of channel protein allows the rapid passage of ions across the membrane?
Which type of channel protein allows the rapid passage of ions across the membrane?
What is the primary factor that influences the direction of glucose transport via GLUT1?
What is the primary factor that influences the direction of glucose transport via GLUT1?
How does simple diffusion differ from facilitated diffusion?
How does simple diffusion differ from facilitated diffusion?
What must be maintained across the plasma membrane for a cell to function?
What must be maintained across the plasma membrane for a cell to function?
Which statement about the anion exchange protein Band 3 is true?
Which statement about the anion exchange protein Band 3 is true?
What type of molecules can typically diffuse through a lipid bilayer most easily?
What type of molecules can typically diffuse through a lipid bilayer most easily?
What effect does solute concentration have on the process of diffusion?
What effect does solute concentration have on the process of diffusion?
Which characteristic of channel proteins aids in facilitating diffusion?
Which characteristic of channel proteins aids in facilitating diffusion?
Which process would most likely occur if the concentration of a solute outside the cell is higher than inside?
Which process would most likely occur if the concentration of a solute outside the cell is higher than inside?
What defines the primary active transport mechanism?
What defines the primary active transport mechanism?
Which type of ATPase is responsible for maintaining ion gradients across plasma membranes in eukaryotic cells?
Which type of ATPase is responsible for maintaining ion gradients across plasma membranes in eukaryotic cells?
What is the function of aquaporins in cell membranes?
What is the function of aquaporins in cell membranes?
What distinguishes indirect active transport from direct active transport?
What distinguishes indirect active transport from direct active transport?
Which of the following describes P-type ATPases?
Which of the following describes P-type ATPases?
How do symport mechanisms in indirect active transport function?
How do symport mechanisms in indirect active transport function?
What is a major role of the Na+/K+ ATPase in animal cells?
What is a major role of the Na+/K+ ATPase in animal cells?
Which type of ion channel is opened by changes in membrane potential?
Which type of ion channel is opened by changes in membrane potential?
What characterizes the structure of porins?
What characterizes the structure of porins?
What is a primary function of active transport mechanisms?
What is a primary function of active transport mechanisms?
How do ABC-type ATPases primarily function?
How do ABC-type ATPases primarily function?
In the context of cell membrane transport, what does the term 'gated' refer to?
In the context of cell membrane transport, what does the term 'gated' refer to?
What type of signal prompts ligand-gated channels to open?
What type of signal prompts ligand-gated channels to open?
Flashcards
Gated Channels
Gated Channels
Ion channels that open and close in response to stimuli.
Voltage-gated channels
Voltage-gated channels
Channels that open or close in response to changes in membrane potential.
Ligand-gated channels
Ligand-gated channels
Channels that open or close when a specific molecule (ligand) binds to them.
Mechanosensitive channels
Mechanosensitive channels
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Porins
Porins
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Porin structure
Porin structure
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Aquaporins
Aquaporins
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Aquaporin structure
Aquaporin structure
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Active Transport
Active Transport
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Direct Active Transport
Direct Active Transport
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Indirect Active Transport
Indirect Active Transport
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Na+/K+ Pump
Na+/K+ Pump
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Sodium Symport
Sodium Symport
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Selectively Permeable Membranes
Selectively Permeable Membranes
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Simple Diffusion
Simple Diffusion
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Concentration Gradient
Concentration Gradient
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Electrochemical Potential
Electrochemical Potential
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Facilitated Diffusion
Facilitated Diffusion
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Carrier Proteins
Carrier Proteins
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Channel Proteins
Channel Proteins
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Uniport Carrier
Uniport Carrier
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Antiport Carrier
Antiport Carrier
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Ion Channels
Ion Channels
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Solute Size
Solute Size
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Solute Polarity
Solute Polarity
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Solute Charge
Solute Charge
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Equilibrium
Equilibrium
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Phosphorylation of Glucose
Phosphorylation of Glucose
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Study Notes
Membrane Transport
- Membranes are selectively permeable, meaning they control what enters and exits.
- This selective permeability is crucial for cell function, allowing the cell to maintain the appropriate concentrations of molecules.
Types of Transport
- Simple diffusion: Small, nonpolar molecules move directly through the phospholipid bilayer from high to low concentration.
- Facilitated diffusion: Large or polar molecules need transport proteins to move across the membrane, still following the concentration gradient.
- Active transport: Movement against a concentration gradient, requiring energy (usually ATP).
Solute Movement Factors
- Size: Small molecules diffuse more easily than large ones.
- Polarity: Nonpolar molecules cross lipid bilayers more readily than polar ones.
- Charge: Polarity and charge hinder molecule transport through the hydrophobic interior of the lipid bilayer, water molecules form hydration shells around the solute.
Channel Proteins
- Ion channels: Form hydrophilic channels for specific ions (e.g., Na+, K+, Cl-).
- Porins: Larger channels found in outer membranes (bacteria, mitochondria, chloroplasts).
- Aquaporins: Specialized channels for water movement.
- Gated channels: Regulated by stimuli: voltages (membrane potential), ligands (molecules binding to the channel), or mechanical forces.
Carrier Proteins
- Carrier proteins: Bind to molecules on one side of the membrane, change shape and release it on the other side. Follow the concentration gradient.
- Uniport: One molecule moving in one direction
- Symport: Two molecules moving in the same direction
- Antiport: Two molecules moving in opposite directions
Example of Specific Transporters
- GLUT1: Glucose transporter - moves glucose into cells via facilitated diffusion
- Na+/K+ ATPase: Moves Na+ out of the cell and K+ into the cell, requires ATP energy.
- Anion exchange protein (Band 3): Exchanges chloride and bicarbonate ions.
Active Transport Mechanisms
- Primary active transport: Directly uses ATP for the transport of a molecule. Requires a protein transporter.
- P-type ATPases: Phosphorylated by ATP, transport ions. E.g., Na+/K+ pump.
- V-type ATPases: Pump protons into organelles (vacuoles, lysosomes)
- F-type ATPases: Transport protons, can also synthesize ATP (known as ATP synthases).
- ABC-type ATPases: Transport a wide variety of molecules; have two binding sites for ATP, important in pumping drugs out of cells.
Indirect Active Transport
- Secondary Active transport: Movement of one substance down its gradient supplies the energy for movement of another substance against its gradient
- Requires a driving force established by the primary active transport pump.
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Description
Explore the concept of membrane transport and how cells regulate the entry and exit of substances. This quiz covers various types of transport mechanisms, including simple diffusion, facilitated diffusion, and active transport, as well as the factors influencing solute movement.
