0
What are two reasons why a substance cannot make it through the lipid bilayer?
Wiki User
∙ 9y ago
1. the substance has a hydrophilic nature
2. the substance is moving against a concentrated gradient
Wiki User
∙ 9y ago
Wiki User
∙ 11y agoThe cell wall is too thick and molecules are unable to pass through
Add your answer:
Earn +20 pts
Is glucose permeable through phospholipid bilayer?
Glucose does not readily diffuse across a lipid bilayer. In order for glucose to travel into the cell, it needs the help of a transport protein. This is called a facilitated diffusion.
Do all substances pass freely between the intracellular and extracellular fluids through a phospholipid bilayer?
No, the membrane is known as semi-permeable because some substances (such as water) can pass freely through - whereas others (such as ions) cannot.
What particles can diffuse directly through the lipid bi-layer?
As the bilayer contains hydrophobic fatty acid tails, water-soluble molecules cannot diffuse directly through. However, lipid soluble molecules such as oxygen can diffuse directly through. Overall, for a molecule to be able to diffuse directly through it must be lipid-soluble, relatively small and non-polar.
What is the chemical biological relevance of polar molecules?
our cells are surrounded by a cell membrane that is a lipid bilayer. this means that the hydrophilic heads, like water, are pointed towards the inside of the cell and the cells' exteriors. this allows polar molecules to move through the membrane and be dissolved within the membrane. the hydrophobic tails of this lipic bilayer are pointed towards eachother. these cannot be in contact with water or nothing will dissolve or be able to pass through them. O==O, the circles are the hydrophilic heads and the lines are the hydrophobic tails.
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.
Why water molecules cannot diffuse directly through the phosolipids bilayer?
Hydrophobic centre of the phospholipid bilayer prevents non-liquid soluble molecules from passing through.
Water freely moves through a phospholipid bilayer Why is this unexpected?
It moves through the bilayer via channels. These channels often are for transfer through the bilayer for other chemicals (sodium, potassium, etc) but also allow water to flow through readily. It is unexpected because water is hydrophilic (obviously- all charged molecules are). The phosphate part of the bilayer can bind with water, but the lipid on the inside of the bilayer acts like a layer of oil on the surface of the water- water cannot pass through the hydrophobic lipid.
Is glucose permeable through phospholipid bilayer?
Glucose does not readily diffuse across a lipid bilayer. In order for glucose to travel into the cell, it needs the help of a transport protein. This is called a facilitated diffusion.
Why is it necessary for glucose to be pumped into the cell rather than diffusing in?
Glucose cannot pass through a phospholipid bilayer by simple diffusion.
Passing an electric current through a certain substance produces oxygen and sulfur This substance cannot be a?
Element.
When you cannot see through a substance is called?
If you can't see through an object clearly it is an opaque object.
Why is it important that ions being transported across a cell membrane be shielded from the interior of the lipid bilayer?
Because the ions are charged, indicating high polarity, which lipids do not possess; they're hydrophobic, and therefore ions cannot pass through the lipid bilayer since lipids are highly unpolar, unless through an ion channel, which has a higher polarity
Why would a substance not be able to pass through a membrane by diffusion?
Water cannot diffuse a plasma membrane because of the fact that the phosphate heads of the phospholipids are hydrophilic, the hydrocarbon tails of the phospholipids are hydrophobic, meaning they repel water. The bilayer phospholipid model of the plasma membrane shows that the phophates face outward on either side of the membrane and the lipid tails are in the middle of the bilayer.
Passing an electric current through a certain substance produces oxygen and sulfur?
it cannot be an element
What can sounds not travel through?
Since sound is a mechanical wave (it needs a substance to travel through) it cannot travel through a vacuum.
What is it called when sand or rock will not dissolve?
When a substance cannot dissolve in another, which usually occurs because one of the substances can interact through the electromagnetic force and the other cannot, the substance is said to be "insoluble" in the other substance.
An uncontrollable substance that cannot be contained?
= An uncontrollable substance that cannot be contained? =
