Biophysical Features of Transport Mechanisms Through Membranes

These flashcards contain essential vocabulary and definitions based on the biophysical features of transport mechanisms through membranes, prepared to aid review for an upcoming exam.

Passive Transport

The movement of molecules across a cell membrane without the use of energy.

Active Transport

The movement of molecules across a cell membrane using energy, typically ATP.

Diffusion

The net flow of particles from a region of high concentration to a region of lower concentration.

Facilitated Diffusion

The process of transporting molecules across a membrane through specific carrier proteins without using energy.

Endocytosis

The process by which cells internalize substances from their environment via vesicles.

Exocytosis

The process by which cells expel materials using vesicles that fuse with the plasma membrane.

Concentration Gradient

A difference in the concentration of a substance across a space.

Saturation Point

The point at which no more of a substance can be absorbed or transported by a system.

Cotransport

The simultaneous transport of two or more substances across a membrane.

Symporter

A cotransporter that moves two types of molecules or ions in the same direction across a membrane.

Antiporter

A cotransporter that moves two types of molecules or ions in opposite directions across a membrane.

Na+/K+ Pump

A type of active transport that moves sodium ions out of and potassium ions into the cell.

Aquaporins

Channel proteins that facilitate the passage of water through the membrane.

Hypertonic Solution

A solution with a higher relative concentration of solute compared to another solution.

Hypotonic Solution

A solution with a lower relative concentration of solute compared to another solution.

Isotonic Solution

A solution with equal relative solute concentrations compared to another solution.

Brownian Motion

Random motion of particles in a fluid resulting from their collisions with other particles.

Fick's First Law

States that the flux is proportional to the concentration gradient.

Chemical Gradient

A difference in the concentration of a chemical across a space.

Membrane Potential

The difference in electric charge across a cell's membrane.

Entropy (ΔS)

A measure of the randomness or disorder of a system.

Free Energy (ΔG)

Energy that can be used to perform work in a system.

Chemical Driving Force

The force that drives the diffusion of substances across a membrane due to concentration differences.

Electrical Driving Force

The force that drives the movement of ions across a membrane due to differences in charge.

Cytoplasm

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

Vesicle

A small membrane-bound sac that transports materials within and outside of cells.

Phagocytosis

The process of cellular ingestion of large particles or cells.

Pinocytosis

The process of cellular ingestion of liquid or small particles.

Receptor-Mediated Endocytosis

A process where cells absorb metabolites, hormones, other proteins, and in some cases, viruses.

Glucose Transporter

A protein that facilitates the transport of glucose across the plasma membrane.

Na+/Ca2+ Exchanger

A mechanism that uses the sodium gradient to facilitate the transport of calcium ions.

Chemical Potential

The potential energy stored in a chemical substance, related to its concentration.

Macroscopic View

Perspective focusing on large-scale phenomena.

Microscopic View

Perspective focusing on small-scale phenomena and interactions.

Cell Membrane

The thin layer of lipid molecules that surrounds the cell.

Lipid Bilayer

The fundamental structure of the cell membrane composed of two layers of phospholipids.

Conformational Change

A change in the shape of a protein that often allows it to perform its function.

Gradient of Physical Quantity

The rate of change of a physical quantity, such as concentration, pressure, or temperature.

Extracellular Fluid

The fluid outside of cells that provides a medium for transport.

Intracellular Fluid

The fluid contained within cells.

Cellular Respiration

The process by which cells convert glucose and oxygen into energy.

Multicellular Organisms

Organisms composed of more than one cell, where cells work together.

Epithelium

A tissue composed of a single layer of cells that lines surfaces in the body.

Membrane Fusion

The process where two lipid bilayers merge to form one.

Transport Proteins

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

Hydrophilic

Substances that are attracted to water and can dissolve in it.

Hydrophobic

Substances that repel water and do not dissolve in it.

Critical Concentration

The concentration of solute at which a certain saturation point is obtained during transport.

Endoplasmic Reticulum

An organelle that assists in the production, processing, and transport of proteins and lipids.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery.

Aquaporin

Water channel protein that facilitates water transport across cell membranes.

Endosome

Membrane-bound compartment in a cell involved in sorting of internalized material.

Phospholipid

A lipid that contains a phosphate group and forms the bilayer of cell membranes.

Calcium Channel

A pore-forming protein that allows calcium ions to pass through the cell membrane.

Na+/glucose Symporter

A transporter that uses the sodium gradient to import glucose into the cell.

Multinuclear Cells

Cells that contain more than one nucleus.

ATP Synthase

An enzyme that produces ATP from ADP and inorganic phosphate during cellular respiration.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Dendritic Cell

An immune cell that processes antigen material and presents it on the cell surface.

Transport Mechanism

The process through which materials move across the cell membrane.

Signal Transduction

The process by which a cell responds to external signals by triggering a series of cellular responses.

Endocytotic Vesicles

Vesicles formed by the process of endocytosis to carry substances into the cell.

Mitochondria

Organelles that are the sites of cellular respiration and energy production.

Transport Pathway

The route that a molecule takes from one side of the membrane to another.

Valinomycin

An antibiotic that selectively transports potassium ions across membranes.

Ion Channel

A membrane protein that allows specific ions to pass through the membrane.

Molecular Transport

The movement of molecules across membranes through various mechanisms.

Hyperosmotic

A solution with a higher osmotic pressure compared to another solution.

Hypoosmotic

A solution with a lower osmotic pressure compared to another solution.

Aquaporin Channel

Specific channels that facilitate water movement across cell membranes.

Calcium Pump

A type of active transport that moves calcium ions against their concentration gradient.

Protein Conformation

The three-dimensional shape of a protein that is essential for its function.

Lysosome

Organelles that contain enzymes to digest cellular waste.

Phagosome

A vacuole formed around a particle engulfed by phagocytosis.

Cell Surface Receptors

Proteins on the cell surface that receive signals from outside the cell.

Cell Signaling

The communication processes that govern basic cellular activities and coordinate cell actions.

Receptor Proteins

Proteins that bind signaling molecules and initiate cellular responses.

Vesicular Transport

The process of moving materials into and out of cells using vesicles.

Transmembrane Protein

A protein that spans the entirety of a cellular membrane.

Glycoprotein

A molecule composed of a protein and a carbohydrate chain, often serving as recognition sites.

Cyclic AMP (cAMP)

A second messenger important in many biological processes.

Ion Concentration

The amount of specific ions present in a given volume.

Transport Control

Regulatory mechanisms that manage the transport of substances across membranes.

Calcium Ion

A critical signaling molecule important in muscle contraction and neurotransmitter release.