Osmosis and Transport Mechanisms in Cells

These flashcards are designed to help students review key vocabulary related to osmosis, transport mechanisms, and cellular processes as described in lecture notes.

Osmosis

The diffusion of water across a selectively permeable membrane.

Selective Permeability

A property of membranes that allows some substances to pass while blocking others.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Isotonic Solution

A solution where the solute concentration is the same as that inside the cell.

Hypertonic Solution

A solution where the solute concentration is greater than that inside the cell.

Hypotonic Solution

A solution where the solute concentration is less than that inside the cell.

Osmoregulation

The control of solute concentrations and water balance in an organism.

Contractile Vacuole

An organelle in some protists that expels excess water.

Turgid

A state of a plant cell when it is firm due to water uptake.

Flaccid

A state of a plant cell when it loses water and becomes limp.

Plasmolysis

The process where the cell membrane pulls away from the cell wall due to water loss, causing cell death.

Facilitated Diffusion

A process where transport proteins speed up the passive movement of molecules across the plasma membrane.

Channel Proteins

Proteins that provide corridors for specific molecules or ions to cross the membrane.

Aquaporins

Channel proteins specifically for the facilitated diffusion of water.

Ion Channels

Gated channels that open or close in response to a stimulus.

Carrier Proteins

Proteins that undergo changes in shape to translocate solutes across the membrane.

Active Transport

The movement of substances against their concentration gradients that requires energy.

Sodium-Potassium Pump

An active transport system that moves sodium out of and potassium into the cell.

Electrochemical Gradient

The combined effect of the concentration gradient and electrical gradient on ion movement.

Electrogenic Pump

A transport protein that generates voltage across a membrane, such as the sodium-potassium pump.

Cotransport

The coupled transport where the active transport of one solute indirectly drives the transport of another.

Exocytosis

The process where transport vesicles fuse with the plasma membrane to release their contents outside the cell.

Endocytosis

The process where cells take in macromolecules by forming vesicles from the plasma membrane.

Phagocytosis

The process of engulfing large particles or cells by a cell.

Pinocytosis

The process of taking in small molecules or droplets of extracellular fluid by a cell.

Receptor-Mediated Endocytosis

The process where binding of ligands to receptors triggers vesicle formation.

Ligand

A molecule that binds specifically to a receptor site of another molecule.

Vesicle

A small membrane-bound sac that transports substances within a cell.

Diffusion

The passive movement of molecules from an area of high concentration to low concentration.

Passive Transport

Movement of substances across a cell membrane without the use of energy.

Membrane Potential

The voltage difference across a membrane due to the distribution of ions.

Chemical Force

The influence of an ion's concentration gradient on its diffusion.

Electrical Force

The influence of the membrane potential on an ion's movement.

Gradient

A difference in concentration or charge across a space.

Transport Proteins

Proteins that facilitate the movement of ions and molecules across membranes.

Fluid Mosaic Model

A model describing the structure of cell membranes as a mosaic of various proteins embedded in a fluid phospholipid bilayer.

Phospholipid Bilayer

A double layer of phospholipids that makes up the cell membrane.

Fluidity of Membranes

The ability of the lipid molecules and proteins within a membrane to move laterally within the layer.

Cholesterol in Membranes

A type of lipid that helps to stabilize membrane fluidity at varying temperatures.

Aquaporin Function

Facilitates the rapid transport of water across cell membranes.

Facilitated Diffusion Features

Does not require energy, utilizes protein channels or carriers.

Hyperosmotic

A solution with a higher concentration of solutes compared to another.

Hypoosmotic

A solution with a lower concentration of solutes compared to another.

Cytoplasm

The jelly-like substance within a cell, excluding the nucleus.

Extracellular Fluid

Fluid outside of cells that provides an environment for cellular functions.

Contractile Vacuole Function

Helps to expel water from cells to maintain osmotic balance.

Plant Cells vs Animal Cells

Plant cells have cell walls which prevent bursting in hypotonic solutions.

Osmotic Pressure

The pressure required to prevent the flow of water across a semipermeable membrane.

Solute Concentration

The amount of solute (e.g., salt, sugar) present in a solution.

Osmotic Movement

The movement of water across a membrane driven by differences in solute concentration.

Cell Wall Function

Provides structural support and helps maintain turgor pressure in plant cells.

Chemical Messenger Transport

Uses endocytosis in neurons for neurotransmitter uptake.

Calcium Ions

Essential signaling molecules in many biological processes, transported by active transport.

Secondary Active Transport

Uses the energy from the electrochemical gradient created by primary active transport.

Vesicular Transport

Transport of larger molecules in vesicles across the cell membrane.

Cytoskeleton Role

Provides structural support and aids in intracellular transport.

Endoplasmic Reticulum Function

Site of protein and lipid synthesis in the cell.

Golgi Apparatus Role

Modifies, sorts, and packages proteins and lipids for secretion.

Lysosome Function

Contains digestive enzymes to break down waste materials in a cell.

Receptor Proteins

Proteins that allow cells to receive signals from outside environments.

Transmembrane Proteins

Proteins that span the entire membrane, involved in transport and signaling.

Hydrophobic Effect

The tendency of nonpolar substances to aggregate in aqueous solutions to minimize their contact with water.

Endocytic Pathways

Different routes for substances to enter a cell, including phagocytosis and pinocytosis.

Signal Transduction

Process by which a cell responds to external signals through receptor activation.

Gated Ion Channels

Ion channels that open or close in response to voltage or ligand binding.

Receptor Activation

Initiation of a cellular response following the binding of a signal molecule to a receptor.

Clathrin

A protein involved in the formation of coated vesicles in endocytosis.

Energy Transfer in Transport

ATP is often used to facilitate active transport mechanisms.

Homeostasis

The maintenance of stable internal conditions in an organism.

Tonicity Importance in Cells

It affects the movement of water and solutes in and out of the cell.