Transport Across Membranes Flashcards
What is the primary function of the plasma membrane?
To regulate the movement of substances in and out of the cell.
True or False: The plasma membrane is permeable to all substances.
False
What is the term for the movement of water across a selectively permeable membrane?
Osmosis
Fill in the blank: __________ transport does not require energy.
Passive
What type of transport requires energy in the form of ATP?
Active transport
Which molecules can easily diffuse through the lipid bilayer?
Small, nonpolar molecules
What is facilitated diffusion?
The process of passive transport of molecules across a membrane via specific transmembrane proteins.
True or False: Ion channels are specific for particular ions.
True
What is the role of carrier proteins?
To transport substances across the membrane by changing shape.
Fill in the blank: The movement of substances against their concentration gradient is called __________ transport.
Active
What is endocytosis?
The process by which cells internalize substances from their external environment.
Name the three types of endocytosis.
Phagocytosis, pinocytosis, and receptor-mediated endocytosis.
True or False: Exocytosis is the process of expelling materials from the cell.
True
What is the significance of the sodium-potassium pump?
It maintains the electrochemical gradient across the plasma membrane.
What does the term ‘selective permeability’ refer to?
The ability of the membrane to allow certain substances to pass while blocking others.
Fill in the blank: __________ proteins span the membrane and aid in transport.
Transmembrane
Which type of transport involves the engulfing of large particles?
Phagocytosis
What is pinocytosis often referred to as?
Cell drinking
True or False: Osmosis only occurs in living cells.
False
What is the main driving force for passive transport?
Concentration gradient
What are aquaporins?
Channel proteins that facilitate the transport of water across the membrane.
Fill in the blank: The __________ potential is the difference in charge across the membrane.
Membrane
What is the main characteristic of active transport?
It moves substances against their concentration gradient.
What is receptor-mediated endocytosis?
A process where cells internalize molecules based on their binding to specific receptors.
True or False: Lipid-soluble substances can pass through the membrane easily.
True
What is the role of cholesterol in the plasma membrane?
To maintain membrane fluidity and stability.
What does ‘tonicity’ refer to?
The ability of a solution to cause a cell to gain or lose water.
Fill in the blank: A solution with a higher concentration of solutes compared to the cell is called __________.
Hypertonic
What happens to a cell in a hypotonic solution?
It swells and may burst due to water influx.
What is the difference between passive and active transport?
Passive transport does not require energy, while active transport does.
What is the function of sodium channels in neurons?
To allow sodium ions to flow into the cell during an action potential.
True or False: Transport proteins can be specific for certain substances.
True
What is the term for the movement of substances out of the cell?
Exocytosis
Fill in the blank: The __________ gradient is the difference in the concentration of a substance across a membrane.
Concentration
What is the net movement direction of water in an isotonic solution?
There is no net movement; water moves equally in both directions.
What does ‘active transport’ often involve?
Transport proteins and ATP.
True or False: Facilitated diffusion requires energy.
False
What happens during depolarization in neurons?
Sodium channels open, allowing sodium ions to enter the cell.
What is the role of the calcium pump?
To transport calcium ions out of the cell against their gradient.
Fill in the blank: The __________ model describes the fluid nature of the plasma membrane.
Fluid mosaic
What is a characteristic feature of channel proteins?
They form passages through the membrane for specific molecules.
What type of molecules typically require facilitated diffusion?
Large or polar molecules.
True or False: All cells use the same mechanisms for transport across membranes.
False
What is the role of the glucose transporter?
To facilitate the transport of glucose into the cell.
Fill in the blank: __________ is the process of cells taking in liquid from the surrounding medium.
Pinocytosis
What happens to an animal cell placed in a hypertonic solution?
It shrinks due to water loss.
What is the significance of the potassium channel?
It allows potassium ions to flow out of the cell, contributing to repolarization.
True or False: All transport across membranes is passive.
False
What does the term ‘membrane potential’ refer to?
The voltage difference across a membrane.
Fill in the blank: The __________ pump is crucial for maintaining sodium and potassium balance in cells.
Sodium-potassium
What is the role of integrins in cell membranes?
To connect the extracellular matrix to the cytoskeleton.
What is the main characteristic of simple diffusion?
It occurs without the assistance of transport proteins.
Fill in the blank: __________ solution has the same solute concentration as the cell.
Isotonic
What is the effect of a hypotonic environment on plant cells?
They become turgid due to water influx.
True or False: Membrane proteins are not involved in transport processes.
False
What is the term for the movement of substances down their concentration gradient?
Diffusion
What type of transport do proton pumps use?
Active transport
Fill in the blank: __________ is the process of engulfing large particles by a cell.
Phagocytosis
What is the role of transport vesicles?
To transport materials within the cell and to the plasma membrane.
What is the primary difference between active and passive transport?
Active transport requires energy; passive transport does not.
True or False: Passive transport can occur through both diffusion and facilitated diffusion.
True
What is the primary mechanism of moving glucose into cells?
Facilitated diffusion via glucose transporters.
Fill in the blank: __________ is the term for the movement of materials from the cell’s cytoplasm to the extracellular space.
Exocytosis
What happens to a red blood cell in an isotonic solution?
It maintains its shape.
What is the role of the aquaporin channel?
To facilitate the rapid transport of water across the membrane.
True or False: The concentration gradient is a driving force for diffusion.
True
What is the process by which cells release neurotransmitters?
Exocytosis
Fill in the blank: __________ transport involves the movement of ions across the membrane.
Active
