Fluidity of the Plasma Membrane and Transport Mechanisms

These flashcards cover the key concepts related to the fluidity of the plasma membrane, transport mechanisms, and the responses of cells in different solutions, as discussed in the lecture.

Membrane Fluidity

The ability of the plasma membrane to change its shape and flexibility, influenced by temperature, fatty acid composition, and cholesterol.

Lateral Movement

The side-to-side movement of phospholipids within the same layer of the bilayer, which is energetically favorable.

Flip-Flop Movement

The rare movement of phospholipids from one leaflet of the bilayer to the other, which is energetically unfavorable.

Cholesterol

A molecule that stabilizes membrane fluidity, reducing fluidity at high temperatures and preventing tight packing at low temperatures.

Simple Diffusion

The passive movement of molecules from high to low concentration without the need for energy or transport proteins.

Facilitated Diffusion

The process of passive transport of molecules across a membrane via specific channel or carrier proteins without energy.

Active Transport

The movement of molecules across a membrane from low to high concentration requiring energy (ATP) and transport proteins.

Amphipathic

Molecules that contain both a hydrophilic (polar) region and a hydrophobic (nonpolar) region.

Osmosis

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

Hypotonic Solution

A solution where water enters the cell, causing it to swell and become turgid due to the cell wall preventing bursting.

Isotonic Solution

A solution where there is no net movement of water, and the cell remains at normal shape and volume.

Hypertonic Solution

A solution where water leaves the cell, causing it to shrivel or crenate.

Endocytosis

The process by which a cell takes substances into the cell using vesicles formed from the plasma membrane.

Phagocytosis

A type of endocytosis that involves the engulfment of large particles such as bacteria or debris.

Pinocytosis

A type of endocytosis that involves the uptake of extracellular fluid and dissolved solutes in small vesicles.

Receptor-mediated Endocytosis

A highly specific process of endocytosis where molecules bind to receptors on the cell membrane before being internalized.