Transport Across Membranes – AP Biology Flashcard

The movement of substances across the cell membrane, crucial for maintaining homeostasis.

Enables cells to acquire nutrients, remove waste, and maintain proper ion concentrations.

Include passive transport (diffusion, facilitated diffusion, osmosis) and active transport.

Movement of substances across the membrane without the use of energy (ATP).

Movement of substances against their concentration gradient, requiring energy (ATP).

A type of passive transport that utilizes specific proteins to help molecules cross the membrane.

Allows for selective transport of larger or polar molecules; does not require energy.

Glucose, amino acids, and ions such as Na+ and K+.

Bind to specific molecules and change shape to transport them across the membrane.

Provide hydrophilic pathways for specific ions and molecules to pass through the membrane.

The process by which cells and organisms maintain water balance and solute concentration.

Essential for maintaining cell shape, function, and overall homeostasis.

Includes the regulation of water intake and excretion, as well as solute concentration adjustments.

Can be classified as passive (diffusion, osmosis) or active (pumps, vesicular transport).

Simple diffusion, facilitated diffusion, and osmosis.

Sodium-potassium pump, proton pump, and endocytosis/exocytosis.

Facilitated diffusion is passive and does not require energy; active transport requires energy.

Molecules move from an area of higher concentration to lower concentration until equilibrium is reached.

Simple diffusion involves direct movement through the lipid bilayer; facilitated diffusion uses specific transport proteins.

The movement of small, nonpolar molecules directly across the phospholipid bilayer.

Occurs down the concentration gradient; no energy is required.

Oxygen, carbon dioxide, and small lipids.

The ability of a solution to affect the shape of a cell by altering its internal water volume.

Isotonic, hypertonic, and hypotonic solutions.

A solution with equal solute concentration compared to the cell, resulting in no net water movement.

A solution with a higher solute concentration than the cell, causing water to exit the cell, leading to shrinkage.

A solution with a lower solute concentration than the cell, causing water to enter the cell, leading to swelling.

Influences cell volume, shape, and function; critical for maintaining cellular integrity.

Involves movement along the concentration gradient; no energy expenditure required.

Generally faster for small, nonpolar molecules; slower for larger, polar molecules.

The passive transport of water across a selectively permeable membrane.

Specialized water channel proteins that facilitate rapid movement of water in and out of cells.

Concentration gradients of solutes and water, membrane permeability, and temperature.

Requires energy to move substances against their concentration gradient.

Include primary active transport (direct use of ATP) and secondary active transport (use of energy from gradients).

Sodium-potassium pump actively transports Na+ out and K+ into the cell.

Glucose-sodium cotransporter uses the Na+ gradient to transport glucose into the cell.

The simultaneous transport of two substances across the membrane in the same direction.

The simultaneous transport of two substances across the membrane in opposite directions.

Differences in ion concentrations create electrical potential, driving the movement of ions.

Bind specific molecules to initiate transport processes or signal transduction pathways.

The process by which cells engulf materials from the extracellular environment.

Includes phagocytosis (cell eating) and pinocytosis (cell drinking).

The process of expelling materials from the cell by fusing vesicles with the plasma membrane.

The transport of large quantities of materials, often through vesicles, requiring energy.

Size, polarity, charge of molecules; temperature and lipid composition of the membrane.

Allows cells to maintain homeostasis by controlling the entry and exit of substances.

Facilitated diffusion is the transport of solutes; osmosis specifically refers to water movement.

Provide specific pathways for the movement of particular substances across the membrane.

Energy is required to move substances against their concentration gradient, essential for cellular function.

Passive transport requires no energy and moves substances down their gradient; active transport requires energy and moves substances against their gradient.

Concentration gradient, temperature, surface area, and size of molecules influence diffusion rates.

Smaller molecules diffuse more readily across membranes than larger ones.

Increased membrane fluidity enhances the mobility of proteins and lipids, facilitating transport.

Sodium ions play a crucial role in maintaining osmotic balance and driving secondary active transport.

Potassium ions are vital for nerve impulse transmission and muscle contraction.

Calcium ions act as signaling molecules and play a role in muscle contraction and neurotransmitter release.

The voltage difference across a cell membrane, essential for action potential in neurons.

Involves receptor binding and subsequent intracellular signaling pathways to modulate transport processes.

Water channel proteins that facilitate rapid water transport across cell membranes.

Lipid and protein composition affects permeability and transport capabilities of the membrane.

Describes the structure of cell membranes as a mosaic of components that move fluidly.

Involves the targeting of specific proteins to different cellular compartments or membranes.

Membrane components are in constant motion, allowing for flexibility and functionality in transport.

Maintaining stable internal conditions through regulated transport of substances is essential for cell survival.