Transportation across cell membranes (1)

Vocabulary flashcards covering the components, structure, and layout models of the cell membrane based on the lecture notes.

Cell Membrane Thickness

The cell membrane is very thin, measuring approximately $8\,nm$ ($8 \times 10^{-9}\,m$).

Selective permeability

A characteristic of the cell membrane that allows it to control the movement of materials by letting some substances cross more easily than others.

Amphipathic

A term describing a molecule, like a phospholipid, that has both a hydrophobic (polar-avoiding) and a hydrophilic (polar-attracting) component.

Phosphate head

The hydrophilic component of a phospholipid.

Lipid tails

The two hydrophobic tails of a phospholipid molecule.

Cholesterol

A steroid that regulates membrane fluidity; it restrains movement at warm temperatures and prevents tight packing to maintain fluidity at cool temperatures.

Peripheral proteins

Proteins that are loosely bound to the surface of the membrane, often acting as cell surface identity markers.

Integral proteins

Proteins that are embedded within the phospholipid bilayer and are very difficult to remove.

Transmembrane proteins

A specific type of integral protein that penetrates and spans across the entire lipid bilayer.

Channel protein

A transport protein that provides a hydrophilic channel across the membrane which is selective for a particular solute.

Signal transduction

A function of membrane proteins involving cell signaling, where molecular signals from the exterior are transmitted to the cell interior.

Cell-cell recognition

A process where cells recognize each other by binding to surface molecules, often carbohydrates, on the plasma membrane.

Extracellular matrix (ECM)

Composed of collagen, enzymes, and glycoproteins, it provides structural anchorage and biochemical support to surrounding cells.

Glycolipid

A membrane carbohydrate that is covalently bonded to a lipid.

Glycoprotein

A membrane carbohydrate covalently bonded to a protein, frequently serving as an identification tag.

Sandwich model

A 1935 layout model of the cell membrane proposed by Davson & Danielli.

Fluid-mosaic model

A 1972 layout model proposed by Singer & Nicolson, describing the membrane as a flexible collection of moving phospholipids and proteins.

Lateral Shift

A type of movement in the cell membrane where molecules move horizontally within the same layer.

Flip Flop

A type of movement in the cell membrane where a molecule moves from one layer of the bilayer to the other.