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Transport Across a Membrane

Some ion channels control the amount of ions going in and out of the cells by having gates that can open and close. Other functions of the proteins include providing receptor sites for hormonal binding, pumping energy to move water-soluble molecules and ions and enzymes that can help to speed up the chemical reactions happening around the membrane.
             Concentration Gradient.
             Before getting into the types of transport across a cell, it is important to know about the concentration gradient. A concentration gradient is the movement of molecules from an area of higher number of particles to a lower number of particles until they are evenly distributed (Study.Com 2003).
             1) Diffusion.
             Firstly, Diffusion is the movement particles from higher concentration to a lower concentration. We can experience diffusion in our everyday life. From the way the scent of your perfume spreads all around the room to the diffusing of the sugar in your tea. However the most important examples of diffusion occurs in our body. This process occurs throughout our body and without it cells and body tissues cannot get important nutrients that are essential for our survival. .
             Lungs.
             The human lungs approximately have 300 million alveoli in each lung. Alveoli is the tiny air sacs in the lungs that are only one cell thick. (Simmons n.d) Our lungs are made in a way that can maximize the surface area to increase gas diffusion. When the blood arriving at the alveoli has a higher concentration of Carbon Dioxide, (as a result of respiration by the body cells) than the alveoli, the carbon dioxide diffuses out of the blood and into the alveolar air. Likewise, when the air in the alveoli has a higher concentration of Oxygen, they move into the blood capillaries by diffusion and combine with the hemoglobin in the red blood cells to form oxyhemoglobin. (Gaseous Exchange in Lungs 2013).
             2) Osmosis.
             Another form of transport between the cells is Osmosis.


Essays Related to Transport Across a Membrane

1. Membranes

Example: Mitochondrial inner membrane has high amounts of functional electron transport system proteins. Plasma membrane, with fewer functions (mainly ion transport), has less protein. ... Molecules to which the membrane is impermeable cannot move across the membrane and so stay on one side or the other. Water diffusion across membranes is a special case and is referred to as osmosis. ... Ions or molecules are moved across the membrane from regions of lesser concentration to regions of greater concentration. ...

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2. Biology - Cell membrane...

Active Transport' is an energy-requiring process that enables material to move across a cell membrane against a concentration difference. There are two types of active transport. ... Special transport macromolecules that exist in the cell membrane move molecules across the membrane. ... Normally they are not able to diffuse across the membrane. ... The second type of active transport, involves large amounts of material being transported through movements of the cell membrane. ...

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3. If Cell Membrane Did Not Exist There is No Life on Earth

The plasma membrane has several functions, for example, they work as a selective permeable barrier, which makes selections to those substances to enter and leave the cell, and this is also known as the transport mechanism functions. ... The transport mechanism contains passive process and active process. The passive process is the movement of substances across the membrane without any consumption of energy, for example, diffusion, which is a net movement of molecules from a region in which they are highly concentrated to a region in which they are less concentrated, to wit, the movement of CO2...

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4. Osmosis And Diffusion

There are two types of diffusion across the membrane barrier: OSMOSIS: It depends on concentration of solutes in an aqueous solution on the two sides seperated by a membrane. ... Facilitated Diffusion: Carrier Proteins and Ion Channels Glucose, sodium ions and choride ions are just a few examples of molecules and ions that must efficently get across the plasma membrane but to which the lipid bilayer of the membrane is virtually impermiable. Their transport must therefore be "facilitated" by proteins that span the membrane and provide an alternative route or bypass. ... Ion channels allow...

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5. Understanding Animal Cells

Introduction There are a great amount of living things across the Earth with one common theme, that is that they are all made up of cells. ... Simple diffusion is a means of passive transport, that is to say that it requires no energy and non polar molecules move freely through the cell membrane from an area of high concentration to the area of lower concentration until equilibrium is achieved. ... These allow transport of larger polarised molecules across the cell membrane by changing their shape to allow the molecule to attach itself to the protein in order to pass through the cell membrane....

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  • Approx Pages: 6
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6. Compartmentalisation in Eukaryotic Cells

However, problems arose from these advantageous adaptions and centre around issues such as substance transport and distribution, rate of macromolecular turnover, diffusion across membranes and the slowed rate of cell replication. ... Required transport of the resultants of these metabolic processes is resolved by the presence of the cytoskeleton. ... Due to the lipid bilayer of the organelle being impermeable to most hydrophilic molecules, it must therefore contain membrane transport proteins (sorting signal) which are responsible for the import and export of specific metabolites. ... The phys...

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7. Semi-Permeable Plasma Membrane - Undergoing Diffusion

In the first tube, the iodine diffuses through the membrane into the dialysis tube. ... This reflects the semi-permeable nature of cell's membrane. ... The spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient is known as osmosis. ... The movement of particles within the processes of diffusion and osmosis both occur across a selectively permeable membrane, which is defined as a membrane that allows certain molecules or ions to pass through it by mean...

  • Word Count: 1659
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8. Environmental Toxicology

The major barrier of uptake for a toxicant is the cell membrane or cell wall at the site of uptake, for example; cell membrane of gastrointestinal tract or skin, epithelial cell of gill and tracheae, or cell wall of plant root. There are four principal processes involved in the movement of toxicants across the cell membrane. These include: passive diffusion, facilitated transport, active transport and pinocytosis. ... The transport into the cell will then be enhanced by carriers during the facilitated transport process. ... Benzene crosses the cell wall or membrane through passive diffusion....

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9. Cell Structures and Organelles (Lab)

There are 2 membranes are visible. 7. ... Therefore, transport in and out of the nucleus can occur in several ways. ... Vesicles are much smaller than vacuoles and function in transporting materials both within and to the outside of the cell. 19. ... Belts of proteins that close, extracellular space between cells, prevent passage of water and water-soluble substances, account for electrical resistance across epithelia, isolate parts of plasma membrane are the roles of tight junction. ... Free ribosomes produce proteins for the cell, while bound ribosomes produce proteins that are transport...

  • Word Count: 1218
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