Cell Transport and Homeostasis

Vocabulary flashcards covering the concepts of cell transport, homeostasis, and the types of passive and active movement across the cell membrane based on the 'It's not Rocket Science®' notes.

Homeostasis

The need of an organism to stay stable by regulating internal conditions.

Dynamic equilibrium

A state that is maintained where conditions aren’t always the same, but things stay within a specific range.

Stimulus

A change in the environment.

Response

A change in the organism as a result of a stimulus.

Selectively permeable

A property of the cell membrane meaning it is picky about what goes in and out.

Passive Transport

The movement of molecules from high concentration to low concentration areas down the concentration gradient, requiring no extra energy by the cell.

Active Transport

The transport of materials into or out of the cell from low to high concentration against the concentration gradient, requiring extra energy ($ATP$) to be spent.

Solute

The substance that gets dissolved in a solution, such as lemonade powder.

Solvent

The substance that does the dissolving in a solution, such as water.

Solution

A uniform mixture of two or more substances.

Concentration

The amount of solute dissolved in solvent, abbreviated with the symbol $[ ]$.

Concentration gradient

The difference in concentration of a substance from one location to another.

Simple Diffusion

The spreading out of molecules across a membrane until equilibrium is reached, moving from high $[ ]$ to low $[ ]$; examples include $O_2$ and $CO_2$.

Facilitated Diffusion

A process where a transport protein helps the diffusion of molecules that normally couldn't pass through the cell membrane, such as glucose ($C_6H_{12}O_6$) or calcium ($Ca^{2+}$).

Osmosis

The movement of water molecules down a concentration gradient from an area where water is more concentrated to an area where water is less concentrated until equilibrium is reached.

Osmotic concentration

Also called osmolarity, it is a measure of how many solute particles are dissolved in a solution.

Aquaporins

Special protein channels in the cell membrane that allow polar water molecules to move quickly and efficiently across the membrane down their concentration gradient.

Hypertonic solutions

Solutions where the water $[ ]$ is lower than the cell’s cytoplasm, causing a net movement of water out of the cell and making the cell shrivel.

Hypotonic solutions

Solutions where the water $[ ]$ is higher than the cell’s cytoplasm, causing a net movement of water into the cell and making the cell swell.

Isotonic solutions

Solutions with an identical water $[ ]$ to the cell’s cytoplasm, resulting in the cell staying the same size.

Molecular pumps

A type of active transport where a cell uses energy to pump molecules like potassium ($K^+$), chlorine ($Cl^-$), and sodium ($Na^+$) across the membrane against the concentration gradient.

Endocytosis

An active transport process that uses vesicles to move large particles into the cell.

Exocytosis

An active transport process that uses vesicles to export materials out of the cell, such as neurotransmitters secreted by nerve cells.

Phagocytosis

A type of endocytosis referred to as cell 'eating' where the cell engulfs solids into a vesicle and digests them.

Pinocytosis

A type of endocytosis referred to as cell 'drinking' where the cell engulfs liquids into a vesicle and digests them.

Lysis

The bursting of an animal cell, such as a red blood cell, when placed in a hypotonic solution.

Crenates

The shrinking of an animal cell when placed in a hypertonic solution.

Turgid

A firm and healthy state for plant cells resulting from being in a hypotonic solution.

Plasmolysis

The process in a plant cell where the cell membrane pulls away from the cell wall due to being in a hypertonic solution.

Flaccid

A limp state in plant cells that occurs when they are in an isotonic solution and are not fully turgid.