Question

Chapter Cellular Structure and Function Wor which consist of fatty acids and alcohol. The phos- The plasma membrane composed mainly of phospholipids, d bilayer As shown in the figure and the tails pholipids in the plasma membrane are tails. bead "loves" water the head and two the membrane. whereas below, each a on the interior of ne cell because water aydophobic). The water-hating tails are tars are hand, point outwards, either the cytoplusm or dhe nuid surrounds if they the other of heads pass the plasma hydrophilic, on exterior Mtolecules that are b can easily membrane. Molecule that are water-loving like the hating like the interior the cause they are through de plasma least rot without help pass Phospholipid molecule Phospholipld bilayer Hydrophilic head Hydrophobic tails hydrophobic, or waterhating, interior The phospholipid bilayer consists of two layers of phospholipids 0eft), with a depicted on the and a hydrophilic, or water-loving, esterior, Asingle phospholipid molecule is Other Molecules in the Plasma Membrane molecules in The plasma membrane also contains other molecules primarily other lipids and proteins. The green the figure above, for example, are the lipid Molecules of cholesterol belp the plasma membrane keep its shape. Many of the proteins in the plasma membrane assist other substances in crossing the membrane. Euensions of the Plasma Membrane plasma membrane may haveextensions, such as whip like nagelt or ke cilia. In single-celled organisms. the membrane estensions may belp organisms move. In multicellular organisms, the extensions have other For example, the cilia the particles the mouth and Dose. Mung cells sweep foreign and mucustoward What is the plasma membrane? 2. What is the meaning of semipen nneabiliry?

Answer 1

1). What is the plasma membrane?

The plasma membrane is a membrane that encloses the cell organelles of a cell. It separates the cell interior and the outside environment. The plasma membrane is semi-permeable membrane that allows selective entry and exit to charged ions and organic molecules. It provides protection to the cell.

2). What is the meaning of semi-permeability?

Semi-permeability is the quality of a membrane to allow passage of some particles through it while restricting the flow of others. The plasma membrane is composed of two layers of phospholipid molecules which have polar phosphate head on the either sides and two non-polar lipid tails embedded inside. Due to this structure, the hydrophilic molecules can not pass through the membrane. Besides, the membrane has transmembrane proteins that may act as channels to allow the passage of specific molecules through them with or without any expense of energy.