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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.
Can all molecules diffuse through all cell membranes?
No, there are specific cell membranes that allow only certain molecules to pass through. Some stay open and others must be opened ( like a gate ).
What are the advantages of semi permeability in cell membrane?
The membrane acts as a barrier that prevents most things from entering. Small molecules and water can diffuse across the membrane but most proteins and larger molecules cannot. The cell can use this advantage in combination with proteins to decide what gets in, what goes out and when that should happen.
What substance cannot pass directly through the phospholipids of the plasma membrane?
Many different things cannot pass through, including sugars, salts and proteins. However, oxygen, water and carbon dioxide can simply diffuse across the membrane.
What are three macromolecules that cannot diffuse across a cell membrane?
Any protein, any fat, and most polypeptides.
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 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.
Can all molecules diffuse through all cell membranes?
No, there are specific cell membranes that allow only certain molecules to pass through. Some stay open and others must be opened ( like a gate ).
What are the advantages of semi permeability in cell membrane?
The membrane acts as a barrier that prevents most things from entering. Small molecules and water can diffuse across the membrane but most proteins and larger molecules cannot. The cell can use this advantage in combination with proteins to decide what gets in, what goes out and when that should happen.
What substance cannot pass directly through the phospholipids of the plasma membrane?
Many different things cannot pass through, including sugars, salts and proteins. However, oxygen, water and carbon dioxide can simply diffuse across the membrane.
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.
Why can oxygen diffuse across a cell membrane but a protein cannot-?
Proteins are to large or Oxygen is much smaller than a protein.
Why can oxygen diffuse across a cells membrane but a protein cannot?
Proteins are to large or Oxygen is much smaller than a protein.
What must be used to transport materials that cannot diffuse across the membrane?
They must pumped actively. So energy in ATP is used.
What the role of protein channels in the cell membrane?
Protein channels are important to facilitate the transport of ions and other larger molecules across the plasma membrane. Large molecules cannot just diffuse thorough the membrane. In addition, polar molecules cannot diffuse through the membrane since it would be energetically unfavorable for them to negotiate the hydrophobic interior of the plasma membrane. Therefore, protein channels are essential in membrane transport.
Why cant polar molecules and ions diffuse across the cell membrane?
Ions cannot diffuse through a phospholipid bilayer because they are not able to dissolve in lipids, hence the phosphoLIPID bilayer . Also, since they have an electrical charge, they are repelled by the membrane.
