Your cells need nutrients. How do these nutrients get into you cell if you have a cell membrane?

Question

please explain so that a 7th grader will understand. thanks!

Answer 1

cell membranes have an active transport system that allows them to transport nutrients like glucose across the cell membrane and into the cell.

Answer 2

By a process of active and passive absorption. The cell membrane is a semi-permeable envelope of lipid that is capable of actively transporting vital nutrients into the body. It does this by creating holes and almost literally dragging in the required nutrient.
Some other smaller nutrients pass in passively by natural breaches in the cell wall and others by a process of osmosis.
It also has to get rid of the wastes of cell metabolism and it does this in reverse.
I don't know how old you are but here are some web sites that may help, and I am sorry if the first link insults you it is not intended to do so. But you will see that the sites ascend from easy (good) to fairly advanced (OK and needs concentration).

Answer 3

The membrane isn't really solid like a piece of paper. It's made of many molecules which just happen to be arranged around the cell. They are constantly moving and rearranging...think a whole bunch of balloons floating on water. Most of these "balloons" are phospholipids. Now embedded between some of these "balloons" are proteins, which provide methods to transport things between the outer environment and the cell.

There are many ways. The basic ones include:
1) Ion channels. Ions flow in and out through a protein with a tunnel, going to the area of lesser ion concentration. This is one example of passive transport, which requires no energy.
2)Facilitated diffusion. Basically a protein with a tunnel through it allows the intake of non-ionic molecules, which tend to be bigger than ions. These are also just allowing molecules to flow through, to the area of lower concentration. Again, passive transport.
3) Active transport. The cell uses energy to transport molecules through proteins. These molecules are transported to areas of higher concentration, known as going against the concentration gradient. This is an example of active transport. It's similar to air freshener when you spray it, except instead of spreading to areas which haven't been freshened, it just compresses itself more (it's not natural, it needs something to force it to do so). On the other hand, when the air freshener actually does spread throughout the room, it's like the two examples of passive transport above; it's natural.
4) Vesicles. Basically little balls of phospholipids form around something to be thrown out of the cell, they go to the membrane and fuse with it while expelling the waste. Or if something wants to come in, the membrane pinches around the molecule and a vesicle can take the molecule wherever it needs to go within the cell.

I didn't go too much into the double layer part of the cell membrane...you can look it up on wikipedia if you want. Just look up phospholipid bilayer. But basically, those proteins I described have to span both layers to provide a path through both layers of the membrane for the cell to interact with its environment. It'll help you understand vesicles more too.

Good luck!

Answer 4

cell membrane is 'semi-permeable', in that it can either let a substance (molecule or ion) pass through freely,
pass through to a limited extent
or not pass through at all.
Cell surface membranes also contain receptor proteins that allow cells to detect external signalling molecules such as hormones.
This membrane serves to separate and protect a cell from its surrounding environment

Answer 5

basically cell membranes have little holes in them that allow some small nutrients to enter but not big ones.. they need to be broken down first

Answer 6

The membrane is semi-permeable. It will transport across in both passive and active ways. It is fluid; not a rigid barrier. Google phopholipid bi layer, or cell membrane.

Answer 7

think of it like a knife going thrugh jello!