Chapter 3.5 Passive Transport + Chapter 3.6 Active Transport

Vocabulary flashcards covering passive transport, facilitated transport, osmosis, active transport, electrochemical gradients, and cellular bulk transport mechanisms.

Selectively Permeable

Refers to membranes that allow some substances through but not others, driven by hydrophilic and hydrophobic regions.

Passive Transport

The most direct forms of membrane transport that do not require the cell to expend energy to accomplish movement.

Diffusion

A process where a substance moves from an area of high concentration to an area of low concentration until equilibrium is met.

Facilitated Transport

Movement of substances from high to low concentration with the help of trans-membrane proteins such as glycoproteins and integral proteins.

Osmosis

The diffusion of water across a membrane from areas of high concentration to low concentration.

Tonicity

Describes the amount of solute in a solution.

Osmolarity

The measure of the tonicity of a solution.

Turgor Pressure

Pressure produced inside plant cells by the influx of water, where cell walls around the plasma membrane prevent lysis.

Active Transport

Transport that requires the use of the cell's energy ($\text{ATP}$) to move substances against a gradient from areas of low concentration to high concentration.

Electrochemical Gradient

The combined force created by both a chemical gradient and an electrical gradient that drives the movement of ions across a cell's plasma membrane.

Electrical Gradient

A difference in electrical charge across a membrane, where the interior of cells is electrically negative ($-$) compared to the extracellular fluid due to net negative large molecules like proteins, nucleic acids, and organic phosphates.

Chemical Gradient

A difference in ion concentration across a membrane, characterized by cells having a high concentration of potassium ($\text{K}^+$) and a low concentration of sodium ($\text{Na}^+$).

Sodium Potassium Pump

A carrier protein pump that continuously pumps $3$ sodium ions ($\text{Na}^+$) out of the cell for every $2$ potassium ions ($\text{K}^+$) brought in, requiring $\text{ATP}$ and keeping the cell interior negative.

Endocytosis

A type of active transport that moves particles, such as large molecules, parts of cells, and whole cells, into a cell.

Phagocytosis

A form of endocytosis responsible for bringing large particles into the cell.

Pinocytosis

A form of endocytosis that takes in fluids, also referred to as cellular drinking.

Receptor-Mediated Endocytosis

A specialized type of endocytosis that utilizes binding proteins to bring material into the cell.

Exocytosis

A transport process that expels material from a cell into the extracellular fluid.