Membrane Permeability Essay

2770 words - 11 pages

Investigating the effects of temperature and ethanol concentration on membrane permeabilityCellular membranes are vital to the function of all cell types. Cellular membranes are selectively permeable, allowing the cell to regulate the transport of substances in and out of the cell. The fluid mosaic model considers membranes to be composed of a phospholipid bilayer with associated proteins (Linder, 2009). Phospholipids are amphoteric molecules with a hydrophilic (water loving) head and hydrophobic (water resisting) tail (Linder, 2009). Associated membrane proteins form a number of roles such as the formation of channels.Cell membranes are selectively permeable barriers (Linder, 2009). Together with proteins, water-soluble molecules are excluded from entering the cell, but permits lipid soluble molecules such as O2, CO2 and alcohol to pass freely through the membrane (Heller, Schaefer, & Schulten, 1993).Vacuoles are organelles found in plants, bacterial, fungal, protists and some animal cells (IHW , 2004). The organelle is protected by a cell membrane and its general function is to maintain internal hydrostatic pressure or turgor within cells (Encyclopedia , 2004 ). The vacuole of beetroot plants contains a water-soluble red pigment called betacyanin (IHW , 2004). When the cells remain in a healthy state, the pigment does not leak through, and remains within the vacuole (Linder, 2009). However when cell membranes are destroyed, the permeability of the tonoplast is damaged causing the betacyanin to leak out from the vacuole and produce a dark pink/red color in the surrounding water (IHW , 2004). Extensive studies have shown that intrinsic membrane proteins, such as ion and water channels are strongly affected from the small changes made within to composition of the cell membrane. Changes in environment, temperature and the influence of alcohol significantly affect membrane permeability, and may lead to cell death (Karp, 2001).Ethanol found in most alcoholic substances interacts with biological membranes, which previous studies have shown that it significantly decreases the levels of membrane integrity (Pantra & Salonen, 2008). Ethanol is lipophilic, and can enter the cell very easily and interferes with the mechanical properties of permeability and diffusion (Westminister College, 2011). This can cause intrinsic proteins such as ion and water channels that regulate the chemical and physical balance in cells to be disturbed. As structure is changed, the membrane increases in permeability, which affects the membranes signaling. Ethanol forms hydrogen bonds that come between the structures of water thus, disrupting its organization (Westminister College, 2011). This leads to the interaction between the hydrophilic end of the membrane and water being disrupted (Pantra & Salonen, 2008).The fluidity of cell membranes also allows the organisms to respond to various environmental changes such as temperature. If temperatures exceed optimum...

Find Another Essay On Membrane permeability

cell Essay

622 words - 3 pages internal environments. The plasma membrane uses the process called the homeostasis which means (metabolic equilibrium maintained by biological mechanisms) to maintains the balance of the cell. By homeostasis plasma membrane helps the cell to stay in shape and flexible. The important part of plasma membrane is the selective permeability. The selective permeability work as the cell ventilation also the selective permeability measures what goes into


949 words - 4 pages EXPERIMENT ONE- BIOLOGY MODEL AnswersTO DETERMINE THE EFFECT OF CHEMICALS AND TEMPERATURE ON MEMBRANE DESTRUCTION AND PERMEABILITY IN BEETROOT (Beta vulgaris)IntroductionThe cell membrane is made up primarily of phospholipids and proteins which contribute to its selectively permeable nature. The function and permeability of the cell membrane depends on its intact structure. When destroyed, the permeability of the cell membrane is disrupted

Study guide chapter 8 for AP Bio (Biology by Campbell and Reece)

961 words - 4 pages may be bonded to the membrane proteins.5. A membrane's molecular organization results in selective permeability. \a. Hydrophobic molecules, such as hydrocarbons, carbon dioxide, and oxygen, can dissolve in the lipid bilayer of the membrane and cross it with ease.6. Some transport proteins function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane. Other transport proteins hold onto their

Notes on Membrane Structure and Function

1153 words - 5 pages *Membrane Structure and Function*Selective permeability- allows some substances to cross it more easily than others*Phospholipids are the most abundant lipids in membranes *An amphipathic molecule (has both hydrophilic and hydrophobic region), proteins too*Overton hypothesized that membranes are made of lipids*Langmuir made artificial membranes by adding phospholipids dissolved in benzene to water*Benzene evaporated, phospholipids

Biological Membranes

2770 words - 11 pages leak through, and remains within the vacuole (Linder, 2009). However when cell membranes are destroyed, the permeability of the tonoplast is damaged causing the betacyanin to leak out from the vacuole and produce a dark pink/red color in the surrounding water (IHW , 2004). Extensive studies have shown that intrinsic membrane proteins, such as ion and water channels are strongly affected from the small changes made within to composition of the


1167 words - 5 pages In life, it is critical to understand what substances can permeate the cell membrane. This is important because the substances that are able to permeate the cell membrane can be necessary for the cell to function. Likewise, it is important to have a semi-permeable membrane in the cell due to the fact that it can help guard against harmful items that want to enter the cell. In addition, it is critical to understand how water moves through the

The Cell of the Human

2960 words - 12 pages variables. The cell membrane allows other materials to enter into the cell when the cell needs these materials. According to Reec, Urry, Cain, Minorsky, Jackson, and Wasserman (2009) who wrote Campbell Biology, the cell membrane is “Selective permeability; that allows some substance to cross it more easily than others. (P.125)” Therefore, whenever the cell needs some materials the responsibility of the cell membrane is to allow these materials to enter


581 words - 2 pages 9.1 PLASMA MEMBRANEI. All cells must maintain homeostasis in order to live.- they do this by controlling what materials can enter and leaveII. All cells have a plasma membrane that is SELECTIVELY PERMEABLE - this only allows for specific things to enter and leave the cellA. Selective permeability is achieved by the structure of the plasma membrane (fig.9.3, pg 220)1. The cell membrane is composed of 2 layers of PHOSPHOLIPIDS -"phospho

Pervaporation for Treating VOCs in Groundwater

2610 words - 11 pages ^M, the permeability of compound in the membrane by P_i^M, and the membrane thickness is represented by T. When considering these equations a few points may be realized. The liquid boundary layer and the membrane are two controlling factors of mass transport. This can lead one to realize that proper membrane selection is very important for successful pervaporation. Selectivity and flux are largely controlled by the membrane which is between the


2018 words - 8 pages molecules into cells should be an unregulated process. If diffusion is an unregulated process, how could some cells have a lower permeability to small molecules than others? Second, scientists have already found membrane proteins that facilitate the entrance of water and urea: While the UT2 protein enables transport of urea past the cell membrane, an entire class of membrane proteins called the aquaporins enable the permeation of water into cells

Determining the Isotonic solution in Sheep Erythrocytes Isotonic solution of red blood cells (Laboratory) red blood cell sizes in saline red blood cell expansion in salt

933 words - 4 pages IntroductionEvery cell is selectively permeable to different molecules. This type of selectively is caused by a semi-permeable membrane, which allows the movement of certain molecules across it. Water exchange can be measured in two ways: RBC osmotic permeability is measured, and diffusional water permeability is measured (Benga and Borza 1995). Diffusion is the movement of high concentration to low concentration. The diffusion of water across a

Similar Essays

Beetroot Cell Membrane Permeability Experiment Essay

1414 words - 6 pages Practical AssessmentPlanningAIMBeetroot cells contain a red pigment, which is stored in the cell vacuole and a vacuole membrane to prevent this leaking out of the cell surrounds it. The outer of the cell is also surrounded by a membrane, which again helps contain the pigment inside the cell. In this experiment I aim to find out the relationship between the leakage of red pigment from a beetroot cell and the surface area. To do this successfully

The Effect Of Temperature On The Permeability Of Beetroot Membrane

1307 words - 5 pages The Effect of Temperature on the Permeability of Beetroot Membrane Analysis The graph shows the colorimeter readings increase as the temperature increases, they increase by the most at higher temperatures. This is shown by a smooth curve. This means that the beetroot samples release more dye at higher temperatures. This is because higher temperatures cause the membrane structure to break down. The membrane

An Investigation To Show How Water Temperature And Alcohol Concentration Affect Membrane Permeability

1290 words - 5 pages An Investigation to Show How Water Temperature and Alcohol Concentration Affect Membrane Permeability Aim The aim of the experiment is to show the cell’s membrane permeability is affected by being placed into different temperatures of water. Also the effect of placing beetroot in to different concentrations of alcohol. Beetroot cells contain a red sap, which leaks out of the cells if their membranes are damaged or altered. Cell

What Is The Effect Of Temperature On Membrane Permeability On Beetroot As Measured By Absorbency Of Pigment?

674 words - 3 pages Research QuestionWhat is the effect of temperature on membrane permeability on beetroot as measured by absorbance of pigment?Background KnowledgeMembrane permeability is affected by the structure of the membrane. Within the membrane, there is cholesterol and proteins maintaining the structure of the fluid mosaic plasma membrane within the globular structure. When proteins denature, it affects the structure of the cell membrane and its