39 Questions
What is the main mechanism by which neurotransmitter activated ion channels are opened and closed?
Mechanical stress
What type of transport is responsible for the movement of water through the paracellular route?
Simple diffusion
Which type of channel is responsible for the selective movement of K+ ions based on ionic radius?
Cation channels of the stereocilliar
What is the primary function of aquaporins in biological systems?
Facilitated diffusion of water
Gramicidin is known for its antimicrobial properties and has a structure composed of:
Alternating D and L amino acids
What defines ionophores as 'ion carriers'?
Reversibly bind ions and have a hydrophilic center along with a hydrophobic portion
Which structure forms a channel large enough for H+, Na+, and K+ ions to pass through, but not Ca2+?
Gramicidin
In facilitated diffusion, what condition must the change in free energy (ΔGt) meet for the process to proceed?
$ΔGt$ must be negative
Which ionophore binds specifically to K+ ions and functions as a K+ transporter?
Valinomycin
What type of energy is stored in concentration gradients and can be quantified?
Potential energy
What is the main difference between carrier proteins and channels in facilitated diffusion?
Carrier proteins can be saturated with substrate, while channels are not saturable
Which statement about facilitated diffusion through channels is accurate?
Channels can transport 104 molecules per second
How do carrier proteins facilitate the transport of molecules in facilitated diffusion?
By changing shape when molecules bind to them, allowing the molecule to cross the membrane
What role do transporter/carrier proteins play in facilitated diffusion?
Become saturated if the solute concentration is too high
In facilitated diffusion, how do carrier proteins interact with solute molecules?
By breaking the solvation layer around the solute
What is a characteristic of ion channels in facilitated diffusion?
They can be gated by ligands, voltage, or touch
Aquaporins are known for their role in facilitating the transport of:
H2O (water)
Ionophores in facilitated diffusion can best be described as:
Ionophores provide a hydrophilic passage across the membrane
Steric factors used by channels in facilitated diffusion refer to the:
Orientation of solute molecules
Rate of flux through channels is approximately 104 times greater than through transporters refers to:
Channels can transport ions more rapidly than carrier proteins
Carrier proteins bind 'substrate' via ______ interactions
non-covalent
Match the following mechanisms of membrane transport with their descriptions:
Simple diffusion = Doesn't require specialized machinery or energy input Facilitated diffusion = Uses membrane proteins to help specific molecules cross the cell membrane Bulk transport = Large-scale movement of fluids influenced by pressure gradients and surface tension Active transport = Requires energy input, typically ATP, to occur
Match the following terms with their roles in membrane transport:
Membrane transport = Process by which cells move materials across their boundaries Cellular homeostasis = Maintaining balance within the cell for overall body health Bulk transport = Mainly occurs via capillaries influenced by pressure gradients ATP (adenosine triphosphate) = Energy source for active transport in cells
Match the following descriptions with the correct types of molecules moved in membrane transport:
Nutrients, waste products, ions = Materials moved by cells in membrane transport Blood, lymph = Fluids moved between tissues in bulk transport Carrier proteins = Aid specific molecules in crossing the cell membrane ATP = Energy source used in active transport
Match the following transport processes with their descriptions:
Uniport = Involves the movement of one type of solute across the membrane through carrier proteins Symport = Involves the movement of two types of solutes in the same direction across the membrane Antiport = Describes the process where two kinds of molecules move in opposite directions through carrier proteins
Pair the following statements with the correct transport process involved:
Transporting substances against concentration gradients = Uniport Using energy released by moving solutes down their concentration gradient = Symport Movement of molecules in opposite directions through carrier proteins = Antiport
Match the following types of ion channels with their activation mechanism:
Ligand-gated channels = Activated by specific neurotransmitters or hormones Voltage-gated channels = Activated by changes in electric potential Stretch-gated channels = Activated by physical stretching of the membrane Ion channels = Not specified in the text
Match the following descriptions with the correct ion channel types:
Activated by neurotransmitters or hormones = Ligand-gated channels Critical for muscle cell function = Voltage-gated channels Activated by physical stimuli = Stretch-gated channels Responsible for maintaining ion homeostasis = Ion channels
Match the following characteristics with their corresponding transport proteins:
Active transport against concentration gradient = Transporters Activation by changes in electric potential = Voltage-gated channels Conformational changes upon ligand binding = Ligand-gated channels Maintenance of ion homeostasis within cells = Transporters
What is the primary function of carrier proteins in facilitated diffusion?
To change shape when molecules bind to them, enabling the molecule to cross the membrane
How do carrier proteins show specificity towards solute molecules in facilitated diffusion?
By binding 'substrate' via non-covalent interactions
What type of kinetics is exhibited by carrier proteins in facilitated diffusion?
Michaelis-Menton kinetics
What is the consequence of carriers becoming saturated with substrate in facilitated diffusion?
Transporters/carriers become saturated if the concentration of molecules to be transported is too high
How do carriers provide a hydrophilic passage across the membrane in facilitated diffusion?
By forming non-covalent interactions with the solute to replace H2O
What is the main function of channels in facilitated diffusion?
To provide a hydrophilic passage across the membrane
How are channels in facilitated diffusion opened and closed?
By binding a specific ligand
What is the role of aquaporins in biological systems?
To facilitate the transport of water
What is the significance of membrane potential in facilitated diffusion?
It provides the driving force for ion movement across the membrane
How do transporters differ from channels in facilitated diffusion?
Transporters change shape to move molecules, while channels provide a continuous passage
Test your knowledge on neurotransmitter-activated ion channels, selectivity filters, facilitated diffusion, and transport mechanisms in biological systems. This quiz covers concepts related to the opening and closing of ion channels by mechanical stress or changes in membrane potential, facilitated diffusion through channels, and the transport of ions and water across different cellular pathways.
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