p.9
Selective Permeability of Membranes
What causes the relative impermeability of polar substances, especially ions?
Their association with water molecules.
p.24
Transport Processes in Cells
What triggers voltage-gated channels to open and close?
Changes in membrane potential.
p.24
Transport Processes in Cells
What are gated channels?
Ion channels that open and close in response to stimuli.
p.6
Concentration Gradient and Electrochemical Potential
What does diffusion tend to create in a solution?
A random solution where the concentration is the same everywhere.
p.52
Active Transport Mechanisms
What does the Na+/K+ pump maintain in animal cells?
Electrochemical ion gradients.
p.47
Types of ATPases in Active Transport
What is the function of the peripheral domains in ABC transporters?
They bind ATP and couple its hydrolysis to transport.
p.33
Active Transport Mechanisms
What determines whether active transport is classified as direct or indirect?
The source of energy and whether two solutes are transported at the same time.
p.36
Indirect Active Transport and Ion Gradients
What is indirect active transport?
A process that depends on the simultaneous transport of two solutes.
p.17
Concentration Gradient and Electrochemical Potential
What dictates the direction of transport in GLUT1?
The relative solute concentrations outside and inside the cell.
p.43
Types of ATPases in Active Transport
What are the two components of F-type ATPases?
A transmembrane pore (Fo) and a peripheral membrane component (F1).
p.10
Concentration Gradient and Electrochemical Potential
What must every cell maintain to function properly?
An electrochemical potential across its plasma membrane.
p.11
Selective Permeability of Membranes
Why can't most substances in the cell cross membranes by simple diffusion?
They are too large or too polar.
p.52
Transport Processes in Cells
Why are the electrochemical potentials for sodium and potassium important?
They serve as a driving force for coupled transport.
p.21
Transport Processes in Cells
How do the lungs contribute to the respiratory system?
They allow for inhalation and exhalation of air.
p.2
Selective Permeability of Membranes
What types of substances typically move across cell membranes?
Dissolved gases, ions, and small organic molecules (solutes).
p.45
Types of ATPases in Active Transport
What is the function of the catalytic domain in ABC transporters?
It binds ATP as part of the transport process.
p.44
Active Transport Mechanisms
What drives the synthesis of ATP by F-type ATPases?
The exergonic flow of protons down their gradients.
p.58
Role of Transport Proteins
What are the proteins responsible for sodium symport called?
Sodium-dependent glucose transporters (SGLT).
p.9
Selective Permeability of Membranes
What factors influence the size of the hydration shell?
The charge of the solute and the size of the solute ions.
p.34
Active Transport Mechanisms
What is direct active transport?
The accumulation of solute molecules on one side of the membrane coupled directly to an exergonic chemical reaction.
p.7
Selective Permeability of Membranes
What type of molecules are lipid bilayers generally more permeable to?
Small molecules like water, oxygen, and carbon dioxide.
p.34
Active Transport Mechanisms
What type of reaction is involved in primary active transport?
Exergonic chemical reaction.
p.7
Role of Transport Proteins
What role do transport proteins play in the movement of small molecules?
They facilitate faster movement of small molecules across the membrane.
p.47
Types of ATPases in Active Transport
What are the characteristics of the two hydrophobic domains in ABC transporters?
They are embedded in the membrane and form a channel.
p.43
Types of ATPases in Active Transport
Where are F-type ATPases found?
In bacteria, mitochondria, and chloroplasts.
p.27
Role of Transport Proteins
What is the central feature of porins?
A water-filled pore at its center.
p.11
Facilitated Diffusion
What is facilitated diffusion?
Protein-mediated movement of substances down their concentration gradient.
p.39
Types of ATPases in Active Transport
What are P-type ATPases?
Members of a large family of enzymes that are reversibly phosphorylated by ATP on a specific aspartic acid residue.
p.21
Transport Processes in Cells
What is the role of alveoli in the lungs?
They are the tiny air sacs where gas exchange occurs.
p.16
Active Transport Mechanisms
What happens to the energy state after glucose binding?
It transitions to low energy state.
p.18
Transport Processes in Cells
What is the consequence of glucose being phosphorylated in the cell?
It is effectively locked into the cell.
p.12
Role of Transport Proteins
What type of segments do transport proteins have?
Some hydrophobic segments and transmembrane segments.
p.15
Role of Transport Proteins
How many transmembrane segments does GLUT1 have?
12 transmembrane segments.
p.4
Concentration Gradient and Electrochemical Potential
What is the effect of a favorable electrochemical potential on energy?
It leads to the release of energy.
p.44
Types of ATPases in Active Transport
What is the function of F-type ATPases in reverse?
They synthesize ATP driven by the exergonic flow of protons down their gradients.
p.32
Active Transport Mechanisms
What is one important function of active transport in cells?
Uptake of essential nutrients.
p.21
Transport Processes in Cells
What is the primary function of the lungs?
To facilitate gas exchange, primarily oxygen and carbon dioxide.
p.9
Selective Permeability of Membranes
What is the effect of charge on solute interaction with water?
Charged solutes attract water molecules, forming a hydration shell.
p.33
Active Transport Mechanisms
What is the primary function of active transport?
To move solutes against their concentration gradient using energy.
p.28
Role of Transport Proteins
What are aquaporins?
Transmembrane channels that allow rapid passage of water.
p.4
Concentration Gradient and Electrochemical Potential
What determines the movement of a solute across a membrane?
Its concentration gradient or its electrochemical potential.
p.39
Types of ATPases in Active Transport
What structural feature do P-type ATPases have?
Transmembrane segments forming a hydrophilic channel.
p.5
Simple and Facilitated Diffusion
What is required for a solute to undergo simple diffusion?
The solute must be small in size and polarity.
p.12
Role of Transport Proteins
What is the function of channel proteins?
To form hydrophilic channels through the membrane, providing a passage route for solutes.
p.58
Indirect Active Transport and Ion Gradients
What is the process of glucose uptake via sodium symport?
It requires energy and utilizes a steep Na+ gradient.
p.24
Transport Processes in Cells
What activates ligand-gated channels?
The binding of certain substances to the channel protein.
p.23
Selective Permeability of Membranes
What do ion channels contain that facilitates ion passage?
Tiny pores lined with hydrophilic atoms.
p.24
Transport Processes in Cells
What do mechanosensitive channels respond to?
Mechanical forces acting on the membrane.
p.28
Selective Permeability of Membranes
How does the movement of water across cell membranes compare to expectations?
It is faster than expected given the polarity of the water molecule.
p.50
Indirect Active Transport and Ion Gradients
What is a symport mechanism in indirect active transport?
A process where the uptake of substances like sugars and amino acids is coupled with the movement of sodium ions into the cell.
p.4
Concentration Gradient and Electrochemical Potential
How is the movement of a molecule with no net charge determined?
By its concentration gradient.
p.39
Types of ATPases in Active Transport
What residue is phosphorylated by ATP in P-type ATPases?
A specific aspartic acid residue.
p.49
Active Transport Mechanisms
Is indirect active transport directly powered by ATP hydrolysis?
No, it is not directly powered by ATP hydrolysis.
p.22
Transport Processes in Cells
What do channel proteins form to facilitate diffusion?
Hydrophilic transmembrane channels.
p.6
Concentration Gradient and Electrochemical Potential
What is the primary direction of solute movement during diffusion?
Toward regions of lower concentration.
p.7
Selective Permeability of Membranes
How do small molecules move across a membrane without transport proteins?
They move more slowly than in the absence of a membrane.
p.16
Transport Processes in Cells
What does glucose bind to in the demonstration?
Its specific binding site.
p.54
Types of ATPases in Active Transport
What is the structure of the Na+/K+ ATPase?
It comprises a transmembrane protein with two alpha (a) and two beta (b) subunits.
p.5
Simple and Facilitated Diffusion
What types of molecules can typically cross a membrane via simple diffusion?
Gases, nonpolar molecules, or small polar molecules like water, glycerol, or ethanol.
p.12
Facilitated Diffusion
How do carrier proteins facilitate diffusion?
By binding solute molecules on one side, undergoing a conformation change, and releasing the solute on the other side.
p.18
Transport Processes in Cells
Why is the concentration of glucose kept low inside the cell?
Due to immediate phosphorylation upon entry.
p.19
Role of Transport Proteins
What is the function of the Erythrocyte Anion Exchange Protein?
Facilitates reciprocal exchange of Cl- and HCO3- ions.
p.12
Transport Processes in Cells
What structural change occurs in carrier proteins during transport?
They undergo a conformation change.
p.10
Concentration Gradient and Electrochemical Potential
Why is the charge of solutes relevant to cell function?
It affects the maintenance of the electrochemical potential gradient.
p.31
Active Transport Mechanisms
What is the relationship between endergonic and exergonic processes in active transport?
Endergonic transport is coupled with an exergonic process to drive movement against the gradient.
p.22
Transport Processes in Cells
What do aquaporins specifically facilitate?
Faster movement of water molecules.
p.2
Transport Processes in Cells
What can cells and cellular compartments do with substances?
They can accumulate a variety of substances in concentrations different from their surroundings.
p.30
Role of Transport Proteins
What is the structure of aquaporins?
Transmembrane segments oriented to form four central channels.
p.5
Simple and Facilitated Diffusion
What is simple diffusion?
The unassisted net movement of a solute from high to lower concentration.
p.54
Sodium-Potassium Pump Functionality
What binding sites are present on the alpha subunits of the Na+/K+ ATPase?
Binding sites for sodium and ATP on the cytoplasmic side, and for potassium on the external side.
p.27
Role of Transport Proteins
What do the polar side chains in porins allow?
Passage of many hydrophilic solutes.
p.15
Transport Processes in Cells
How does the erythrocyte uptake glucose?
By facilitated diffusion.
p.36
Indirect Active Transport and Ion Gradients
What is a symport in the context of indirect active transport?
Transport of two molecules in the same direction.
p.48
Medical Significance of ABC Transporters
What is a common characteristic of drug-resistant human tumors?
They have high concentrations of the MDR transporter protein.
p.50
Sodium-Potassium Pump Functionality
What is the role of the Na+/K+ pump in animals?
To maintain a high extracellular concentration of sodium ions.
p.42
Types of ATPases in Active Transport
Where does the peripheral component (V1) of V-type ATPases extend?
Juts out from the membrane surface.
p.4
Concentration Gradient and Electrochemical Potential
What determines the movement of an ion across a membrane?
Its electrochemical potential, which includes both concentration and charge gradients.
p.22
Role of Transport Proteins
What are the three types of channel proteins?
Ion channels, porins, and aquaporins.
p.13
Role of Transport Proteins
In which state is the solute binding site accessible on one side of the membrane?
In one of the two conformational states of the carrier protein.
p.23
Transport Processes in Cells
What are ion channels?
Transmembrane proteins that allow rapid passage of specific ions.
p.34
Types of ATPases in Active Transport
What are transport proteins driven by ATP hydrolysis called?
Transport ATPases or ATPase pumps.
p.25
Role of Transport Proteins
What are porins?
Transmembrane proteins that allow rapid passage of various solutes.
p.12
Role of Transport Proteins
What are transport proteins?
Large, integral membrane proteins with multiple transmembrane segments.
p.8
Selective Permeability of Membranes
Why do nonpolar substances dissolve readily into the lipid bilayer?
Because they can easily enter the hydrophobic region.
p.42
Types of ATPases in Active Transport
Which organelles are affected by V-type ATPases?
Vacuoles, vesicles, lysosomes, endosomes, and the Golgi complex.
p.23
Transport Processes in Cells
Which ions require separate channels for transport?
Na+, K+, Ca2+, and Cl-, among others.
p.48
Medical Significance of ABC Transporters
What is the role of the MDR transporter protein?
It is associated with multidrug resistance in human tumors.
p.15
Concentration Gradient and Electrochemical Potential
Why can glucose enter the erythrocyte?
Because the level of blood glucose is much higher than that inside the cell.
p.42
Types of ATPases in Active Transport
Where is the integral component (V0) of V-type ATPases located?
Embedded in the membrane.
p.31
Active Transport Mechanisms
What is required for transporting substances against a concentration gradient?
Coupling endergonic transport to an exergonic process, usually ATP hydrolysis.
p.50
Indirect Active Transport and Ion Gradients
How does the sodium ion gradient facilitate the uptake of nutrients?
The high extracellular concentration of Na+ drives the uptake of sugars and amino acids.
p.49
Indirect Active Transport and Ion Gradients
What is often coupled to the inward transport of molecules in indirect active transport?
Simultaneous inward movement of Na+ (in animals) or protons (in plants, fungi, bacteria).
p.1
Selective Permeability of Membranes
What needs to be selectively moved across cell membranes?
Specific molecules and ions.
p.7
Selective Permeability of Membranes
What type of molecules can pass through the membrane rapidly?
Polar molecules, with some cells having channels for water.
p.36
Indirect Active Transport and Ion Gradients
How does secondary active transport function?
Movement of one solute down its gradient drives the movement of another solute up its gradient.
p.23
Role of Transport Proteins
Why are separate channels needed for different ions?
Because most channels allow passage of just one specific ion.
p.32
Active Transport Mechanisms
What characteristic does active transport have regarding direction?
Active transport has intrinsic directionality.
p.8
Selective Permeability of Membranes
Can large nonpolar molecules cross membranes easily?
Yes, examples include estrogen and testosterone.
p.25
Role of Transport Proteins
How do the pores formed by porins compare to ion channels?
They are larger and less specific than ion channels.
p.42
Types of ATPases in Active Transport
What are the two components of V-type ATPases?
An integral component (V0) and a peripheral component (V1).
p.53
Active Transport Mechanisms
What process does the Na+/K+ ATPase use to drive the transport of ions?
Exergonic hydrolysis of ATP.
p.27
Role of Transport Proteins
What do the nonpolar side chains in porins interact with?
The hydrophobic interior of the membrane.
p.15
Role of Transport Proteins
What do the transmembrane segments of GLUT1 form?
A cavity with hydrophilic side chains.
p.41
Types of ATPases in Active Transport
Do P4-ATPases transport molecules all the way across the bilayer?
No, they do not transport them all the way across.
p.13
Role of Transport Proteins
What happens to the solute binding site during the conformational change of a carrier protein?
It shifts from one side of the membrane to the other.
p.32
Active Transport Mechanisms
How does active transport contribute to ion concentrations?
It maintains nonequilibrium concentrations of certain ions.
p.30
Role of Transport Proteins
What is the function of the central channels in aquaporins?
To allow water molecules to pass through.
p.25
Role of Transport Proteins
Where are porins found?
In the outer membranes of bacteria, mitochondria, and chloroplasts.
p.57
Transport Processes in Cells
How does most glucose move into and out of cells?
By facilitated diffusion.
p.31
Active Transport Mechanisms
What is active transport?
Protein-mediated movement of substances against a concentration gradient.
p.8
Selective Permeability of Membranes
What happens to solutes with polarity when crossing the cell membrane?
They pass through more slowly compared to nonpolar substances.
p.5
Simple and Facilitated Diffusion
What direction does simple diffusion occur?
From higher concentration to lower concentration.
p.28
Role of Transport Proteins
In which plant cells do aquaporins facilitate rapid water passage?
Root cells and vacuolar membranes.
p.11
Concentration Gradient and Electrochemical Potential
How does the solute move during facilitated diffusion?
As dictated by its concentration gradient.
p.38
Types of ATPases in Active Transport
What are the four types of transport ATPases identified?
P-type, V-type, F-type, and ABC-type.
p.10
Selective Permeability of Membranes
What must membranes allow for in relation to ions?
Controlled crossing of ions across the bilayer.
p.38
Active Transport Mechanisms
What is the role of transport ATPases?
To facilitate direct active transport across membranes.
p.41
Types of ATPases in Active Transport
What do P4-ATPases transport?
Hydrophobic molecules, such as cholesterol and fatty acids.
p.48
Medical Significance of ABC Transporters
Why are ABC transporters medically significant?
They can pump antibiotics or drugs out of cells, making the cells resistant to the drugs.
p.16
Concentration Gradient and Electrochemical Potential
What is the state of the energy gradient for the protein before glucose binding?
High electrochemical gradient.
p.28
Role of Transport Proteins
In which animal cells do aquaporins facilitate rapid water passage?
Erythrocytes and kidney cells.
p.23
Selective Permeability of Membranes
What determines the selectivity of ion channels?
Binding sites involving amino acid side chains and a size filter.
p.19
Role of Transport Proteins
What is another name for the Erythrocyte Anion Exchange Protein?
Chloride-bicarbonate exchanger Band 3.
p.48
Medical Significance of ABC Transporters
How do ABC transporters affect tumor growth?
They can render tumor cells resistant to drugs that normally inhibit tumor growth.
p.40
Types of ATPases in Active Transport
What roles do P2-ATPases play in eukaryotic cells?
Muscle contraction and acidification of gastric juices.
p.18
Transport Processes in Cells
What effect does phosphorylation have on glucose's ability to bind to the carrier protein?
Once phosphorylated, glucose cannot bind to the carrier protein.
p.25
Role of Transport Proteins
What structure do the transmembrane segments of porins form?
They cross the membrane as beta barrels.
p.36
Indirect Active Transport and Ion Gradients
What is an antiport in the context of indirect active transport?
Transport of two molecules in different directions.
p.53
Sodium-Potassium Pump Functionality
What ions are pumped by the Na+/K+ ATPase?
Sodium (Na+) and Potassium (K+).
p.1
Selective Permeability of Membranes
What does it mean that membranes are selectively permeable?
They allow specific molecules and ions to move in and out of the cell or organelle.
p.50
Active Transport Mechanisms
What is the relationship between ATP and the sodium ion gradient?
The pump that maintains the sodium ion gradient is driven by ATP.
p.19
Transport Processes in Cells
What occurs during the exchange of ions by the Erythrocyte Anion Exchange Protein?
One molecule moves in while another moves out.
p.4
Simple and Facilitated Diffusion
What type of movement does simple or facilitated diffusion involve?
Exergonic movement 'down' the concentration gradient.
p.10
Concentration Gradient and Electrochemical Potential
How do ions move across the membrane in relation to electrochemical potential?
From high electrochemical potential to low.
p.15
Role of Transport Proteins
What is the function of GLUT1?
It is a glucose transporter that facilitates glucose transport inward.
p.1
Selective Permeability of Membranes
Why is overcoming the permeability barrier of cell membranes important?
It is crucial for the proper functioning of the cell.
p.31
Transport Processes in Cells
What does facilitated diffusion account for?
Movement of molecules down a concentration gradient toward equilibrium.
p.38
Types of ATPases in Active Transport
What do the different types of transport ATPases vary in?
Structure, mechanism, location, and roles.
p.41
Types of ATPases in Active Transport
What do P3-ATPases of plants and fungi do?
They pump protons out across the plasma membrane, acidifying the external medium.
p.41
Types of ATPases in Active Transport
What is known about P5-ATPases?
They are not well characterized, but some are known to transport cations.
p.13
Role of Transport Proteins
What model describes how carrier proteins function?
The alternating conformation model.
p.13
Role of Transport Proteins
What triggers the release of the solute in carrier proteins?
The shift to the alternate conformation.
