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How does eukaryotic and prokaryotic organisms undergo facilitated diffusion?
Diffusion is the ability of molecules to follow a concentration gradient, moving from regions of high to low concentration. For small, nonpolar molecules such as O2, CO2, and some narcotics, they are small enough to slip through the phospholipid bilayer of the plasma membrane. Small, polar molecules such as water, are also small enough to slip through, but because of their polar nature, this movement is impeded by a factor of 1000. What about larger molecules like glucose? These molecules are too big to slip through the phospholipid bilayer, regardless of the concentration gradient. Larger molecules require a protein channel for transport across the plasma membrane. Because the movement will be driven by the concentration gradient, this movement is called facilitated diffusion, to indicate that a protein channel is necessary. Both prokaryotic and eukaryotic cells have protein channels for this purpose.
How would a polar molecule like water travel through the plasma membrane?
The structure of cell membrane allows nonpolar molecules to diffuse, but not polar molecules. Membrane architecture is in the form of a phospholipid bilayer. A single phospholipid has a "head" composed of a polar NH3 group, and two "tails" composed of nonpolar fatty acids. The lipids spontaneously arrange themselves into bilayers with the hydrophilic heads directed outward, and the hydrophobic tails facing inward. Because nonpolar solvents can only dissolve nonpolar solutes, polar molecules cannot mix with the nonpolar inside of the lipid bilayer. A polar molecule cannot cross the cell's lipid membrane without aid from a carrier protein. While this is true, there are multiple forces that dictate whether or not a molecule can cross a phospholipid membrane, including electrochemical gradients and size. Very small and non-polar molecules have a very easy time crossing the phospholipid bilayer. However, very small, polar molecules like water can also cross the phospholipid bilayer due to hydrostatic pressure and concentration gradient differences. Water will, but with some difficulty because of it's polarity. Aquaporins, protein channels embedded into cellular membranes allow for sufficient amounts of water to diffuse into cells.
How do materials move through simple diffusion?
Materials move through simple diffusion by the process of random molecular movement, where molecules naturally spread from areas of higher concentration to areas of lower concentration. This movement occurs across permeable membranes without the need for energy input, as substances seek to achieve equilibrium. Small, nonpolar molecules, such as oxygen and carbon dioxide, are typically able to diffuse easily through cell membranes, while larger or charged molecules may require facilitated diffusion or active transport.
Where exactly in the membrane do small nonpolar and small polar molecules pass through?
Small nonpolar molecules pass through the lipid bilayer of the cell membrane primarily through simple diffusion, as they can easily dissolve in the hydrophobic core of the membrane. In contrast, small polar molecules typically require specific transport proteins, such as channels or carriers, because their polarity prevents them from easily crossing the hydrophobic interior of the membrane. While some small polar molecules can pass through the membrane via facilitated diffusion, it is generally more challenging compared to nonpolar molecules.
What solute moves fastest in a cell?
In a cell, small nonpolar molecules, such as oxygen and carbon dioxide, typically move the fastest through the lipid bilayer of the cell membrane via simple diffusion. Their small size and nonpolar nature allow them to easily pass through the hydrophobic core of the membrane without the need for transport proteins. Additionally, ions and small polar molecules can also move quickly through specific ion channels or transporters, but their movement is generally slower compared to nonpolar molecules.
Can nonpolar molecules cross the cell membrane?
Yes, nonpolar molecules can cross the cell membrane through simple diffusion.
Diffusion of nonpolar molecules would not be affected by?
Diffusion of nonpolar molecules would not be affected by factors such as temperature, concentration gradient, or the presence of other nonpolar molecules. Nonpolar molecules are able to diffuse freely through cell membranes and other barriers due to their lack of charge, making them less influenced by these factors compared to polar molecules.
Is oxygen able to pass directly through the phospholipid bilayer?
Yes, oxygen molecules are small and nonpolar, allowing them to pass directly through the phospholipid bilayer of cells by simple diffusion. This is one of the reasons why oxygen can easily enter and exit cells to support cellular respiration.
How does eukaryotic and prokaryotic organisms undergo facilitated diffusion?
Diffusion is the ability of molecules to follow a concentration gradient, moving from regions of high to low concentration. For small, nonpolar molecules such as O2, CO2, and some narcotics, they are small enough to slip through the phospholipid bilayer of the plasma membrane. Small, polar molecules such as water, are also small enough to slip through, but because of their polar nature, this movement is impeded by a factor of 1000. What about larger molecules like glucose? These molecules are too big to slip through the phospholipid bilayer, regardless of the concentration gradient. Larger molecules require a protein channel for transport across the plasma membrane. Because the movement will be driven by the concentration gradient, this movement is called facilitated diffusion, to indicate that a protein channel is necessary. Both prokaryotic and eukaryotic cells have protein channels for this purpose.
Describe how the diffusion of ions across a cell membrane differs from the diffusion of nonpolar molecules across the cell membrane?
Ions need to be facilitated through a cell membrane because they are passing through a phospholipid bilayer with a hydrophobic interior. Non polar molecules are also hydrophobic, so they can pass through the membrane easily if they are small enough. Ions are polar, so they have a hard time passing through membranes.
What part of a phospholipid is not attracted to water?
The hydrophobic tails of a phospholipid are not attracted to water. This is because they are made up of fatty acid chains that are nonpolar and prefer to interact with other nonpolar molecules, avoiding water.
Which molecules move during diffusion?
In diffusion, molecules move from an area of high concentration to an area of low concentration. This movement is driven by random kinetic energy and does not require a membrane or cellular energy. Small, nonpolar molecules such as oxygen, carbon dioxide, and lipid-soluble compounds diffuse easily across cell membranes.
Are fatty acid tails of a phospholipid molecules polar?
This is called the hydrophobic 'side' of the phospholipid molecule
A phospholipid molecule has a polar and a nonpolar end because of this water molecules form what kind of bond?
hydrogen bonds with the polar end of the phospholipid molecule
What are the process in which materials move through a cell membrane?
diffusion and osmosis
What are the examples of simple diffusion?
Examples of simple diffusion include the movement of oxygen and carbon dioxide across the cell membrane, as well as the movement of small nonpolar molecules such as ethanol and urea. This process does not require any energy input and occurs down a concentration gradient.
How would a polar molecule like water travel through the plasma membrane?
The structure of cell membrane allows nonpolar molecules to diffuse, but not polar molecules. Membrane architecture is in the form of a phospholipid bilayer. A single phospholipid has a "head" composed of a polar NH3 group, and two "tails" composed of nonpolar fatty acids. The lipids spontaneously arrange themselves into bilayers with the hydrophilic heads directed outward, and the hydrophobic tails facing inward. Because nonpolar solvents can only dissolve nonpolar solutes, polar molecules cannot mix with the nonpolar inside of the lipid bilayer. A polar molecule cannot cross the cell's lipid membrane without aid from a carrier protein. While this is true, there are multiple forces that dictate whether or not a molecule can cross a phospholipid membrane, including electrochemical gradients and size. Very small and non-polar molecules have a very easy time crossing the phospholipid bilayer. However, very small, polar molecules like water can also cross the phospholipid bilayer due to hydrostatic pressure and concentration gradient differences. Water will, but with some difficulty because of it's polarity. Aquaporins, protein channels embedded into cellular membranes allow for sufficient amounts of water to diffuse into cells.
