Podcast
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?
What is the role of carrier proteins in facilitated diffusion?
What is the role of carrier proteins in facilitated diffusion?
Why do polar substances, particularly ions, have low permeability across membranes?
Why do polar substances, particularly ions, have low permeability across membranes?
What keeps the concentration of glucose low inside animal cells?
What keeps the concentration of glucose low inside animal cells?
Signup and view all the answers
What characterizes facilitated diffusion as a transport process?
What characterizes facilitated diffusion as a transport process?
Signup and view all the answers
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?
Signup and view all the answers
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?
Signup and view all the answers
How does simple diffusion differ from facilitated diffusion?
How does simple diffusion differ from facilitated diffusion?
Signup and view all the answers
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?
Signup and view all the answers
Which statement about the anion exchange protein Band 3 is true?
Which statement about the anion exchange protein Band 3 is true?
Signup and view all the answers
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?
Signup and view all the answers
What effect does solute concentration have on the process of diffusion?
What effect does solute concentration have on the process of diffusion?
Signup and view all the answers
Which characteristic of channel proteins aids in facilitating diffusion?
Which characteristic of channel proteins aids in facilitating diffusion?
Signup and view all the answers
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?
Signup and view all the answers
What defines the primary active transport mechanism?
What defines the primary active transport mechanism?
Signup and view all the answers
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?
Signup and view all the answers
What is the function of aquaporins in cell membranes?
What is the function of aquaporins in cell membranes?
Signup and view all the answers
What distinguishes indirect active transport from direct active transport?
What distinguishes indirect active transport from direct active transport?
Signup and view all the answers
Which of the following describes P-type ATPases?
Which of the following describes P-type ATPases?
Signup and view all the answers
How do symport mechanisms in indirect active transport function?
How do symport mechanisms in indirect active transport function?
Signup and view all the answers
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?
Signup and view all the answers
Which type of ion channel is opened by changes in membrane potential?
Which type of ion channel is opened by changes in membrane potential?
Signup and view all the answers
What characterizes the structure of porins?
What characterizes the structure of porins?
Signup and view all the answers
What is a primary function of active transport mechanisms?
What is a primary function of active transport mechanisms?
Signup and view all the answers
How do ABC-type ATPases primarily function?
How do ABC-type ATPases primarily function?
Signup and view all the answers
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?
Signup and view all the answers
What type of signal prompts ligand-gated channels to open?
What type of signal prompts ligand-gated channels to open?
Signup and view all the answers
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.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
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.
