Diffusion, Osmosis, and Cellular Transport

Phagocytosis is the process of engulfing large particles (cellular eating), while pinocytosis is the process of taking in extracellular fluid and dissolved solutes (cellular drinking).

Endocytosis is the general term for the process by which cells take in large particles or fluids from the outside environment by engulfing them in a vesicle.

Exocytosis is the process by which cells move large particles or waste out of the cell by fusing a vesicle with the plasma membrane.

Active transport requires energy to move molecules against their concentration gradient, and the primary energy currency of the cell is ATP.

Active transport is the movement of substances across a cell membrane against their concentration gradient, which requires the expenditure of energy.

An isotonic solution has the same concentration of solutes as the cell, meaning water moves into and out of the cell at the same rate, resulting in no net change in cell volume.

The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time; it can only remain constant or increase, meaning the universe tends toward disorder.

In a hypotonic solution, the solute concentration outside the cell is lower than inside. To balance this, water moves into the cell via osmosis, which can cause the cell to swell.

In a hypertonic solution, the solute concentration outside the cell is higher than inside. Water moves out of the cell to balance this concentration gradient, causing the cell to shrink.

A hypertonic solution has a higher solute concentration outside the cell than inside. This environment causes water to exit the cell.

Passive transport is the movement of substances across a membrane without the use of cellular energy. Diffusion, osmosis, and facilitated diffusion all fit this description.

A membrane that allows substances to pass through is described as permeable. Semi-permeable refers to allowing only specific substances to pass.

Facilitated diffusion is a type of passive transport where carrier proteins assist molecules in moving down their concentration gradient.

Passive transport is the general term for the movement of substances down a concentration gradient that does not require cellular energy.

A solvent is the substance, typically a liquid, that dissolves a solute to form a solution.

An impermeable membrane is one that does not allow any substances to pass through it.

A solute is the substance that is dissolved in a solvent to create a solution.

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.

Equilibrium occurs when the concentration of a substance is uniform throughout a space, meaning there is no net movement.

Osmosis is specifically the diffusion of water across a semi-permeable membrane from a region of high water concentration to low water concentration.