L3 - Control of the Cellular Environment

Flashcards about cell membrane, diffusion, osmosis and ion channels.

Plasma Membrane

The membrane encasing the cell, providing a barrier between the inside and outside.

Phospholipid Bilayer

The structure of the plasma membrane, composed of two layers of phospholipids with hydrophobic tails facing inward and hydrophilic heads facing outward.

Diffusion

The random motion of molecules leading to an equal distribution in a given space, eliminating concentration gradients.

Osmosis

The movement of water through a semipermeable membrane from an area of high water concentration to an area of low water concentration.

Tonicity

The relative concentration of solutes between two different compartments, affecting the movement of water.

Isotonic

Two solutions with the same concentration of solute.

Hypotonic

A solution with a lower solute concentration compared to another solution.

Hypertonic

A solution with a higher solute concentration compared to another solution.

Membrane Proteins

Proteins embedded in the cell membrane that facilitate the passage of specific molecules or ions across the membrane.

Channels

Membrane proteins that allow facilitated diffusion of molecules down their concentration gradient.

Transporters

Membrane proteins that bind to specific molecules and transport them across the membrane, either through facilitated diffusion or active transport.

Active Transport

The movement of molecules across the cell membrane against their concentration gradient, requiring energy input (e.g., ATP hydrolysis).

Aquaporins

Proteins in the cell membrane that need to regulate large amounts of water flows.

Electrochemical Gradient

The combination of both the concentration gradient and the electrical potential difference that affects the movement of ions across a membrane.

Sodium-Potassium ATPase

An active transporter that uses ATP to pump three sodium ions out of the cell and two potassium ions into the cell, establishing electrochemical gradients.

Resting Membrane Potential

The electrical potential difference across the cell membrane when the cell is not stimulated, typically negative due to ion distribution and charged molecules within the cell.

Action Potential

A rapid change in the electrical potential across the cell membrane in neurons and muscle cells, involving coordinated movement of ions through ion channels.

Endocytosis

The process by which cells engulf molecules or particles from the extracellular environment by forming vesicles from the cell membrane.

Exocytosis

The process by which cells release molecules or particles to the extracellular environment by fusing vesicles with the cell membrane.

Phagocytosis

A form of endocytosis in which a cell engulfs larger particles or even other cells.