How do molucules flow into and out of cells?

Question

How do molucules flow into and out of cells?

Answer 1

There are many ways molecules can move into and out of cells. To determine how a molecule may entre of leave a cell you need to first determine what kind of molecule it is!

The cell membrane as it is does not allow hydrophilic molecules through (because its made up of hydrophobic molecules). Therefore most ions cannot move through this barrier. Large molecules also have a hard time getting through this barrier. Water on the other hand can passively move its way into and out of the cell with ease.

Now how might a cell want to get a molecule into a cell? There are multiple ways.

Passive Diffusion:

- The molecule can naturally get through the membrane, (not an ion, and small ex H20). This is gradient driven, meaning if the molecules on the outside are of higher concentration, it will move into the cell (or vice versa)

Facilitated Diffusion:

- proteins will actually for a channel in the membrane, which allows specific molecules (which nomrally can pass the membrane) through. Also concentration driven.

Active Diffusion:

- a protein will expend energy to move molecules in an out of a cell. They need to use energy since you are moving molecules against the concentration gradient.

Endocytosis:

- a receptor on the outside of the cell may come into contact with a wanted molecule, which will cause the cell to 'envelop' the molecule to being it inside.

Exocytosis:

- opposide of endocytosis, cell wants to expell molecules.

Answer 2

Molecules can flow into and out of celles several ways depending on the size, charge, and concentration of the molecule

The cell wall of eukaryotes is made up of two lipid (fat + cholesterol) layers. The two layers create a "sandwhich" center that is hydorphobic or rejects polar molecules. The outside layers are hydrophilic or mix well with polar substances. Throughut the cell wall are protiens that act as channels or transportaion for molecules that are too large, polar, or molecules that need energy to overcome a gradient.

00x000  hydrophilic head (fatty acids)

lllllxlll    hydrophobic tail

lllllxlll     hydrophobic tail

00x00  hydrophillic head

the x represents a protein

Polar molecules slip through the membranes (diffusion). Other molecules are small enough also, like water (which travels by osmosis to the higher solute concnetrated side). Most molecules however use the protien transports to cross.

For most molecules, there exists a gradient or a side that has a higher concentration. The molecules flow downhill, from high concentration to low by diffusion or transport. In order to go uphill, or from low to high concentration, energy (ATP) is needed, which is called active transport.

All of these happen constantly as the body maintains a homeostatsis.

Answer 3

Salt and potassium are the opposing electrolytes that cause the nutrients and water to get drawn into and out of cells. Your cells however have a semipermeable membrane which allows nutrients to pass while keeping the cellular parts from dispersing all over the place. When nutrients are drawn into the cell, the cellular power houses start to work. (mitochondria) They produce energy for the cell to continue it's function. I hope you are not depending on me for a homework answer because it has been years since I learned this in school.

Answer 4

Small, uncharged molecules move through the phospholipid bilayer itself.

Larger molecules move through ion or protein channels.

Process-wise, molecules travel in and out of cells through osmosis, diffusion, facilitated diffusion (all three are types of passive transport), or through active transport (including endocytosis, and exocytosis).