Membranes and Their Functions Essay

Membranes contain phospholipid bilayer these are two layers of phospholipids which are facing in opposite directions to each other. The non-polar tails are hydrophobic which are water-hating, what makes it difficult for polar molecules/ions to pass through them are the fatty acid tails which also act as a barrier to water-soluble substances. These molecules move in and out of the cell by diffusion, osmosis and active transport. Diffusion is the net movement of particles down a concentration gradient for example when gases move about and will move from where there is a high concentration to where they are in lower concentration. By osmosis, the diffusion of water through the plasma membrane is possible because the lipids bilayers are water-resistant to important molecules and small molecules like oxygen and carbon dioxide, these molecules and ions diffuse freely across the cell membrane. By active transport, ions and molecules are forced using metabolic energy to move against their concentrated gradient.

Introduction: Cell membranes contain many different types of molecules which have different roles in the overall structure of the membrane. Phospholipids form a bilayer, which is the basic structure of the membrane. Their non-polar tails form a barrier to most water soluble substances. Membrane proteins serves as channels for transport of metabolites, some act as enzymes or carriers, while some are receptors. Lastly carbohydrate molecules of the membrane are relatively short-chain polysaccharides, which has multiple functions, for example, cell-cell recognition and acting as receptor sites for chemical signals.

All cells have a cell membrane. The structure of membranes is formed from a double layer of phospholipids with proteins floating in it. The proteins are embedded on the surface and inside or bridge the double layers of phospholipids. This structure is called a mosaic model. The main function of cell membranes is to provide protection and support for the cell and they also control what enter and exit the cell to maintain internal balance, called homeostasis. There are two types of a membrane protein: integral proteins and peripheral proteins. The integral membrane proteins are

The cell membrane of eukaryotic cells is composed of a phospholipid bilayer. These phospholipids are composed of a polar head, made up of a phosphate group, and two non-polar fatty acid tails. This amphipathic nature of phospholipids creates a semi-permeable membrane, fluid enough to allow for the growth and movement of the cell but solid enough to hold the shape of the cell. The phospholipids of the membrane are arranged tail to tail which create a protective, hydrophobic region in between the bilayer. This hydrophobic area prevents many types of molecules from entering the cell including large, polar or charged molecules. This is an important feature for the regulation of substances and concentrations inside and outside the cell. However, it can become a problem because most vital molecules are unable to pass through the membrane through simple diffusion. For example, water is essential for a cells survival. Water is also a polar molecule. The cell allows water to pass in and out by using the process facilitated diffusion.

A cell membrane functions as a selective barrier between the cytoplasm and the extracellular fluid. This allows the cell to monitor what is permitted into and out of the cell because some molecules are permeable and others are not. The membrane is composed of phospholipid molecules that are characterized by their amphipathic nature, which means there is a polar and nonpolar end of the molecule. The head is water loving or hydrophilic and the tail is lipid loving or lipophilic. The difference in

The cellular membrane is a selectively-permeable phospholipid bilayer that also contains embedded proteins as well as cholesterol which gives the membrane its fluidity. A phospholipid molecule has two ends, a head and tail; the head is hydrophilic, meaning it is attracted to water molecules, while the tail end is hydrophobic and not attracted to water molecules. Selectively-permeable means it will let certain molecules into the cell, while making sure certain particles stay out. The proteins located in the membrane take over as the mechanism to move different molecules in and out of the cell.(“What is a semipermeable membrane?, 2015”)

The reason substances need to move through cell membranes is to balance out the solutes on either side of the membrane. When the substances inside a cell have the same concentration of solutes as the substances outside of the cell, the solution is isotonic. When the concentration of solutes is greater on one side of the membrane than the other, that side of the solution is hypertonic. The side that has a lower concentration of solutes is hypotonic.

This is a desirable property for membrane molecules because in cellular membranes, there is two fatty acids, helping make up the cellular membrane. The fatty acids are hydrophobic tails, this allows for the membrane to create a lipid bilayer as the hydrophobic tails face each other, away from the water, leaving the hydrophilic heads on the outside. This makes the cell membrane semi-permeable. Without the fatty acids, the cell membrane would not have the ability to be semi-permeable nor would it create a lipid bilayer.

Its function is to protect the interior of the cell by allowing certain substances to pass into the cells. But It also maintain other substances out of Its surface. It also functions as a membrane to support the cell and maintain its appropriate shape. The cell membrane is primarily structured of a combination of proteins and lipids that lead to the accurate cell functions. lipids provide membranes flexibility and proteins.

The outer membrane consists of a phospholipid bilayer (Membrane that has a hydrophilic, water repelling side, and a hydrophobic, water attracting side), spreading throughout integral proteins. The phospholipid bilayer contains porins which allow the passage of molecules that are 10,000 Daltons (Biochemical measure of proteins, the chemist in me likes to say atomic mass units: the two are equivalent) or less. The permeable membrane allows for ions, water and some certain proteins to flow freely into the membranes working

Lipids are responsible for many critical functions in cells which includes their role of being the primary component of the cell membrane. Lipids cause electric signal

The cell membrane surrounds the cytoplasm of a cell and is the barrier as to what can and cannot pass through the cell. The cell membrane acts as a barrier and is one of the many key factors for supporting life, without it diffusion and osmosis would not be able to occur. The barrier is selectively/partially permeable and regulates what enters and exits the cell, therefore facilitating the transport of materials needed for survival. There is two processes in which substances are carried across the membrane, either passive transport or active transport. Passive transport transpires without the input of cellular energy albeit Active Transport requires cells to expend energy to move the substance across the barrier. The cell membrane also maintains cell potential.

The membrane controls what passes into and out of cell. According to OpenStax College (2013), states that the membrane allows substances to enter and leave a cell (OpenStax College, 2013). The membrane is selectively permeable and the process by which molecules pass through the cell membrane can be accomplished by diffusion, osmosis, facilitated transport and active transport. Diffusion is the movement of molecules from high concentration to a region of low concentration (OpenStax college, 2013). Osmosis is the process by which water pass through a semi-permeable membrane. Facilitated transport, also known as facilitated diffusion is the movement of particular molecules down a concentrated gradient. Active transport is the process in which

The cell membrane’s function is to control what goes in and out of the cell. The membrane isolates the area of cytoplasm from the external environment and regulates the exchange of entering and exiting molecules. Cell membranes communicate with other organelles to function properly.(Muskopf). A quality of the membrane is that it is selectively permeable. This means that certain substances may pass through the membrane more easily than others. The cell membrane consists of a phospholipid bilayer and embedded proteins.(Feldkamp, page 73). Another characteristic of the cell membrane is the idea of passive transport. Passive transport is when certain substances inside of the cell can move throughout the membrane without the use of the cells

The cell membrane is a barrier that controls what substances can go in and out of the cell. Through cell membrane substances such as Oxygen and nutrients molecules enters the cell while carbon dioxide and other wastes come out through it. To understand many aspects of Physiology, it is important to understand the mechanism that transports substance across the cell membrane. sThe flow of substances into and out of the cells is called Osmosis. During osmosis, the water molecules flow through a semipermeable membrane from a less concentrated solution through a higher concentrated one in effort to equalize the concentration of water on both sides of the membrane. Hypertonic solution is any solutions with a higher salt concentration than the body