1.3 Cell Membrane Transport Overview

The difference in concentration of substances between the interior and exterior of a cell.

A double layer of lipids (fats) that forms the outer boundary of a cell, acting as a selective barrier.

The process where molecules move from areas of high concentration to areas of low concentration, following the concentration gradient.

Type of diffusion where a carrier protein helps a molecule cross the cell membrane.

The process of molecules moving against their concentration gradient, requiring energy.

A transporter protein that moves sodium (Na+) ions out of the cell and potassium (K+) ions into the cell. Requires energy (ATP).

The state where a molecule can easily pass through the cell membrane because it is similar in structure to the membrane's lipid content.

Proteins embedded within the cell membrane that assist in the movement of various molecules across the membrane.

A process where the movement of one substance down its concentration gradient provides energy for another substance to move against its gradient.

A type of secondary active transport where the movement of sodium ions down their concentration gradient powers the transport of glucose into the cell.

A mechanism of moving substances across a sheet of cells, involving transport through the cell membrane on one side and either simple or facilitated diffusion on the other.

The active transport of sodium ions across the cell membrane creates a high concentration gradient, causing water to move by osmosis.

The active transport of sodium ions across the cell membrane leads to the simultaneous movement of water, due to the osmotic gradient created.

Movement of molecules across a cell membrane without the help of carrier proteins. It can occur through the lipid bilayer (for lipid-soluble substances) or through water-filled channels (for some water-soluble substances).

The rate of diffusion is directly proportional to the molecule's lipid solubility. This means lipid-soluble molecules move more easily across the membrane.

Water-filled channels in cell membranes that specifically transport water. These channels are known as aquaporins.

These are open tubules formed by integral membrane proteins, providing a pathway for molecules to pass through the cell membrane.

These are specialized proteins that allow only specific molecules to pass through the cell membrane. They are highly selective and can be open or closed by gates.

Protein channels regulated by the binding of a specific chemical substance, or ligand, to the channel.

Protein channels regulated by changes in the electrical potential across the cell membrane.

The movement of molecules across a membrane due to a difference in concentration. Molecules move from an area of high concentration to low concentration. (Think of a drop of ink spreading in water.)

The movement of ions across a membrane due to a difference in electrical potential. Opposites attract, so positive ions move to areas with a negative charge, and vice versa.

This is a state of equilibrium. The concentration gradient and electrical gradient balance each other out and there is no net movement of ions across the membrane.

The pressure required to stop the movement of water across a selectively permeable membrane. This pressure is created by the concentration of solute particles on one side of the membrane.

This is the movement of water across a selectively permeable membrane from a region of high water concentration to a region of low water concentration.

The process by which a cell takes in molecules from the surrounding environment. This is a type of active transport that requires energy.

The process by which a cell releases molecules to the surrounding environment. This is a type of active transport that requires energy.

The concentration of a solution expressed as the number of particles per unit volume, often measured in osmoles per liter (Osm/L).

The concentration of a solution expressed as the number of particles per unit mass of solvent, often measured in osmoles per kilogram (Osm/kg).

Active transport that directly utilizes energy released from ATP hydrolysis.

A process where the sodium-potassium pump moves three sodium ions out of the cell for every two potassium ions pumped in, contributing to the membrane potential.

The difference in electrical potential across a cell membrane, typically negative inside the cell due to the active transport of ions.

A process that controls cell volume by regulating the movement of ions and water across the cell membrane.

The transport of molecules or ions across a membrane in the same direction, driven by the concentration gradient of one of the substances.

The transport of molecules or ions across a membrane in opposite directions, driven by the concentration gradient of one of the substances.

The process of maintaining low intracellular calcium concentrations through active transport, essential for muscle function.

The active transport of hydrogen ions, important for maintaining acid-base balance in the stomach and kidneys.

Secondary active transport that utilizes the concentration gradient of sodium ions to drive the movement of other substances across the membrane.