Selective Permeability: Allows some substances to cross it more easily than others. A phospholipid is an amphipathic molecule, meaning it has both a hydrophilic region and a hydrophobic region. Fluid Mosaic Model: The membrane is a fluid-structure with a “mosaic” of various proteins embedded in or attached to a double layer (bilayer) of phospholipids. The…
All cells are enclosed by a membrane composed of lipids, proteins and carbohydrates. Eucaryotic cells also have internal membranes that divide the cell into different compartments. Biological membranes have several important functions, including: They separate the contents of a cell or organelle from the surrounding environment. They control import and export of molecules (e.g., nutrients,…
The materials used in building the bodies of living things are limited to the atoms and molecules that make up this planet. To maintain life on Earth, matter must be recycled. Cycling of Organic Matter Living things are constantly cycling matter through their bodies and in ecosystems; break down organic matter and rebuild it. Organic…
Biological molecules are macromolecules, which basically means they are polymers composed on small repeating units that have been covalently bonded together. The exception to this is a type of lipid called triacyleglycerides or phospholipids which are relatively large molecules composed of smaller molecules bonded together. Subunits are chemically liked together in the cell by a…