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The cell membrane is mostly composed of phospholipid molecules. Each of these has a polar head and a non-polar tail part. The polar bits are attracted to water (hydrophilic) , and the non-polar parts repel water (hydrophobic).
In the membrane, they form a double layer - like a sandwich - the polar heads stick out, and the tails form the middle, like the filling inside the sandwich. This way, the inner and the outer surfaces of the membrane are hydrophilic, being on "good terms" with the water in the outer environment and the water in the cytoplasm.
At the same time, the membrane separates these two aqueous environments from each other - exactly because there is a non-polar middle layer, that does not allow polar substances to cross to the other side.
What else can I help you with?
What types of molecules can diffuse through the cell membrane without using a channel protein?
Small, non-polar molecules like oxygen, carbon dioxide, and water can diffuse through the cell membrane without the need for a channel protein. Their small size and non-polar nature allow them to passively pass through the lipid bilayer of the membrane.
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.
Why do Ions and polar molecules require transport proteins to enter or leave a cell?
Not necessarily. It helps to be polar because the lipid bilayer is polar and it helps to pull molecules through, but if its a molecule that the cell doesn't want it wont pull it through. Water (a polar molecule) can go through the membrane anywhere but other nutrients need the help of transport proteins.
What structure does oxygen diffuses through but a sodium ion may need active transport?
Oxygen can diffuse through the cell membrane, which is selectively permeable to small non-polar molecules. On the other hand, sodium ions are charged and larger, so they typically require active transport mechanisms such as protein pumps to move across the cell membrane.
What two membranes need to be broken down to release DNA from a plant cell?
The cell wall and the cell membrane need to be broken down to release DNA from a plant cell. These barriers protect the DNA inside the cell and need to be disrupted to access the genetic material.
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 types of molecules can diffuse through the cell membrane without using a channel protein?
Small, non-polar molecules like oxygen, carbon dioxide, and water can diffuse through the cell membrane without the need for a channel protein. Their small size and non-polar nature allow them to passively pass through the lipid bilayer of the membrane.
What is the purpose of the cell membrane.?
The cell membrane regulates the passage of chemicals in or out of the cell. It is made up of a phospholipid Bi-layer consisting of many lipids much like the ones found in a detergent (Hydrophillic heads and hydrophobic tails). The tails avoid water and stay together - this makes a water proof barrier. A cell membrane is known as partially permeable as it allows non-polar molecules (or very small polar molecules such as CO2) to pass through but stops larger polar molecules, H2O for example, from passing, this is useful as it prevents excessive water loss from the cell. The cell membrane is more detailed but for your question there is no need for that.
Why do you need cholesterol in the cell membrane?
It prevents the lipids on the cell membrane from sticking together
What substances easily diffuse a class of cell membrane?
Lipid-soluble substances, such as oxygen, carbon dioxide, and small non-polar molecules, easily diffuse across the cell membrane. These substances can pass through the lipid bilayer of the membrane without the need for specific transport proteins.
Does plant cells need a cell membrane?
Yes plant cells need a cell membrane. In addition to the cell membrane they also have a cell wall. Animal cells however do not have a cell wall but merely a membrane. A cell is not able to live without a membrane as it holds the organelles and cytoplasm in place.
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.
Why does the cell need a cell membrane?
because they need to keep them self save
Does a cell wall need a cell membrane?
Of course yes
Why do Ions and polar molecules require transport proteins to enter or leave a cell?
Not necessarily. It helps to be polar because the lipid bilayer is polar and it helps to pull molecules through, but if its a molecule that the cell doesn't want it wont pull it through. Water (a polar molecule) can go through the membrane anywhere but other nutrients need the help of transport proteins.
What Particular molecules or ions freely cross the plasma membrane with assistance?
large polar molecules cannot pass through the membrane. only nonpolar and small polar molecules can pass through, and they only go from high to low concentration or else they need assistance from active transport.
What do animals have that replaces a cell wall?
A cell membrane. They don't need a cell wall.
