There are proteins in the membrane that have channels for large polar molecules to move into or out of the cell since the plasma membrane is made of a phospholipid bilayer where the inside is non polar. This means large polar molecules need help from proteins to cross the plasma membrane.
<h2><em><u>Human space exploration helps to address fundamental questions about our place in the Universe and the history of our solar system. Through addressing the challenges related to human space exploration we expand technology, create new industries, and help to foster a peaceful connection with other nations.</u></em></h2>
