Unit 2 Movement of materials in and out of cells

Diffusion

The process of movement of particles from an area of high concentration to low concentration, occurring in liquids and gases.

Concentration Gradient

The difference in concentration between two regions, driving the movement of particles during diffusion.

Equilibrium

The state reached when diffusion stops and particles have equal concentration in all areas.

Factors affecting the speed of diffusion

Concentration, mass, and temperature affect how fast diffusion occurs.

Cell Membrane

A barrier that holds cells together, allowing certain substances to move in and out through selective permeability.

Permeability

The ability of a membrane to allow substances to pass through.

Simple Diffusion

Movement of small or fat-soluble substances directly through the phospholipids of the cell membrane, occurring down the concentration gradient without energy.

Facilitated Diffusion

Diffusion that occurs through transport proteins for medium-sized or water-soluble substances down their concentration gradient without energy.

Active Transport

The movement of substances against their concentration gradient, requiring energy input.

Exocytosis

The process of transporting large substances out of the cell using a vesicle.

Endocytosis

The process of transporting large substances into the cell, which includes phagocytosis (cell eating) and pinocytosis (cell drinking).

Osmosis

The diffusion of water across a selectively permeable membrane from low solute concentration to high solute concentration.

Isotonic Solution

Solution with the same concentration of solutes and solvents.

Hypertonic Solution

Solution with a higher concentration of solutes compared to the cell, leading to water loss and cell shrinkage.

Hypotonic Solution

Solution with a lower concentration of solutes compared to the cell, leading to water influx and potential cell bursting.

Turgid

The state of a plant cell when it is full of water and firm.

Flaccid

The state of a plant cell when it has lost water and becomes soft.

Plasmolysis

The process in which the cell membrane pulls away from the cell wall due to water loss in a hypertonic environment.

Contractile Vacuole

An organelle in freshwater protozoa that expels excess water to prevent osmotic bursting.

Diffusion

Movement of particles from an area of high concentration to an area of low concentration; occurs in liquids and gases.

Factors affecting diffusion speed

Concentration, mass, temperature.

Cell membrane

Structure that holds the cell together, allows substances to move in and out; selectively permeable.

Simple diffusion

Substances move through the cell membrane directly through phospholipids (e.g., O2, CO2, fatty acids).

Facilitated diffusion

Diffusion aided by transport proteins (e.g., glucose, amino acids, water, ions).

Active transport

Movement of substances against the concentration gradient, requiring energy.

Endocytosis

Transport of large substances into the cell via vesicle formation; includes phagocytosis (cell eating) and pinocytosis (cell drinking).

Exocytosis

Transport of large substances out of the cell via vesicle fusion with the cell membrane.

Osmosis

Net movement of water molecules across a selectively permeable membrane from low to high solute concentration.

Isotonic

Solution with the same concentration of solutes and solvent as the cell.

Hypertonic

Solution with more solutes and less solvent than the cell.

Hypotonic

Solution with fewer solutes and more solvent than the cell.

Contractile vacuole

Organelle in freshwater protozoa (e.g., Paramecium) that expels excess water to prevent bursting.