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Cells have a variety of molecule attached to their membranes. Some of these molecules respond to different stimuli and allow substance to pass in and out of the cell. They can voltage gated, ion gated channels, ligand gated. Cells also engage in pinocytosis, phagocytosis, and exocytosis. This is when the cell membrane engulfs a substance and takes it it or when a membrane bound vesicle fuses with the cell membrane to expel a substance.
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What large molecules need help getting across cell membrane?
In general, molecules that cannot diffuse across the cell membrane are either very large, such as starches and fats, or very polar.
What substance cannot pass directly through the phospholipids of the plasma membrane?
Large polar molecules and charged molecules cannot pass directly through the phospholipids of the plasma membrane because the phospholipid bilayer is impermeable to them. Instead, these molecules rely on specific transport proteins like channels or carriers to facilitate their movement across the membrane.
Can all molecules diffuse through all cell membranes?
No, not all molecules can diffuse through all cell membranes. The ability of a molecule to diffuse through a cell membrane depends on its size, charge, and solubility in lipids. Small, non-polar molecules can generally pass through the lipid bilayer of cell membranes via simple diffusion, while larger, polar molecules may require specific transport mechanisms.
What are three macromolecules that cannot diffuse across a cell membrane?
Any protein, any fat, and most polypeptides.
Can ATP passively diffuse across cell membrane?
The universal energy molecule of the cell, adenosine triphosphate (ATP) cannot passively diffuse across the cell membranes. Despite its low molecular weight, ATP carries a strong negative charge making it hydrophilic and thus unable to diffuse across the lipophilic cellular membrane.
What large molecules need help getting across cell membrane?
In general, molecules that cannot diffuse across the cell membrane are either very large, such as starches and fats, or very polar.
Why can oxygen diffuse across a cell membrane but a protein?
Its too large
What must be used to transport materials that cannot diffuse across the membrane?
Transport proteins, such as channels and carriers, must be used to transport materials that cannot diffuse across the membrane. These proteins facilitate the movement of specific substances across the cell membrane by providing a passageway or binding site for the molecules to move through.
Why did osmosis, but not diffusion of sucrose molecules, occur across the dialysis membrane containing 20% sucrose solution?
Sucrose cannot diffuse across a dialysis tubing. This is because it's size is too large to go through the tubing. Water can diffuse across.
What substance cannot pass directly through the phospholipids of the plasma membrane?
Large polar molecules and charged molecules cannot pass directly through the phospholipids of the plasma membrane because the phospholipid bilayer is impermeable to them. Instead, these molecules rely on specific transport proteins like channels or carriers to facilitate their movement across the membrane.
Why can oxygen diffuse across a cell membrane but a protein cannot-?
Proteins are to large or Oxygen is much smaller than a protein.
Can oxygen diffuse across a cell membrane?
No, oxygen cannot directly diffuse across a cell membrane. Instead, it crosses the cell membrane with the help of specific transport proteins, such as aquaporins and oxygen channels. These proteins facilitate the movement of oxygen from areas of high concentration to low concentration.
Why can oxygen diffuse across a cell membrane but a protein can't?
Oxygen is a small, non-polar molecule that can passively diffuse across the lipid bilayer of a cell membrane. Proteins, on the other hand, are larger and more complex molecules that cannot pass through the hydrophobic core of the membrane. Instead, proteins are transported into or out of cells through specific channels or transporters.
What are three macromolecules that cannot diffuse across a cell membrane?
Any protein, any fat, and most polypeptides.
Can all molecules diffuse through all cell membranes?
No, not all molecules can diffuse through all cell membranes. The ability of a molecule to diffuse through a cell membrane depends on its size, charge, and solubility in lipids. Small, non-polar molecules can generally pass through the lipid bilayer of cell membranes via simple diffusion, while larger, polar molecules may require specific transport mechanisms.
What molecules won't diffuse passively across a membrane?
Larger molecules, such as glucose. The cell membrane is made up of phospholipid molecules, which are phosphate "heads" with two lipid "tails". Since the lipid tails are nonpolar, and thus hydrophobic (do not dissolve in water, and are repelled), polar molecules, like water, cannot pass through the membrane. Certain small, nonpolar molecules like oxygen and carbon dioxide can fit through without the use of energy. Large molecules and some ions (for example, Na+ and K+ in the sodium-potassium pump) are drawn into the cells by carrier proteins, possibly up the concentration gradient, which requires energy.
Why can oxygen diffuse across a cells membrane but a protein cannot?
Proteins are to large or Oxygen is much smaller than a protein.
