4.+Cell+Membrane

===Explanations should be well thought out, written in full sentences, and in your own words. You will not receive credit for plagiarism. You may include graphics if they will support your explanation, but be sure to include a link to the image's source. ===

=4. Describe what happens at a cell membrane.= What happens at the cell membrane is that it decides what goes in and out of the cell.Small molecules,including h20,co2,o2 and the soluble end products of digestion,pass easily through the cell membrane.Larger molecules,such as proteins and starch,cannot pass through the cell membrane.The cell membrane doesnt only take things depending on their size sometimes molecules bind together as they go in and out of the cell membrane.these molecules go through the cells special receptor.this is the only way binding molecules,which bind in the special receptor can leave.The shape of these receptor site molecules are highly specific to the shape of the molecules being transported. 