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a cell wall, or cell membrane is selectively permeable, meaning it will let some things in and not others. this selective-ness is key to maintain homeostasis, if a cell were to let in everything and let nothing out, it would swell and burst.
think of a chain link fence, or a colander. these have holes in them to let some things through and keep others in. you couldn't fit a pig through a colander, could you?
What else can I help you with?
Why do passenger molecules need to be helped by the carrier protein?
Some molecules can't go through the cell membrane.
Do substances enter any plant or animal cell by passing through a cell membrane?
Molecules can not pass through the cell membrane, because endocytosis is important for those large molecules that can not pass through the cell membrane!!
Why do cell need transport proteins to functions?
Some molecules are too large to pass through the cell membrane without transport proteins.
Why doesn't protein pass through the cell membrane?
Cell membrane consist of phosholipid layres and have small pores in it aproximately of the size of 80nm which allows only those molecules which are smalles then this pore size. So it is semi or selective permeable.
What is a selectlively permeable membrane?
The cell membrane is selectively permeable, allowing some molecules to pass through by osmosis
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.
Why can't all receptors be located inside the cell?
Not all receptors can be located inside the cell because some receptors need to be on the cell surface to interact with molecules outside the cell, such as hormones or neurotransmitters. These external molecules cannot pass through the cell membrane to reach receptors inside the cell.
Why do cells need to use transport proteins to function?
Carbohydrates cannot pass directly through the cell membrane. some important molecules are too large to pass through the cell membrane
What is meant by cell membrane is semipermeable?
It allows only certain molecules to pass through.
How can some substance diffuse through a cell membrane at faster rate than by diffusion alone?
In facilitated diffusion, there are temporary openings in the cell membrane that enable certain molecules to pass through quickly.
Where are the ATP molecules formed in fermentation?
In fermentation, the ATP molecules are formed in the cytoplasm of the cell through glycolysis. This process involves the breakdown of glucose to produce ATP, which can then be used as energy for cellular activities.
What type of molecules enter the cell through passive transport List at least three?
Small nonpolar molecules like oxygen and carbon dioxide, as well as water molecules, can enter the cell through passive transport. Other examples include lipids and ethanol.
