<p>Imagine protein X, destined to go to the plasma membrane of a cell. Assume that the mRNA carrying the genetic message for protein X has already been translated by ribosomes in a cell culture. You collect the cells, break them open, and then fractionate their contents by differential centrifugation. In the pellet of which fraction would you expect to find protein X? Explain your answer by describing the transit of protein X through the cell.</p>
<p>Is this your homework or do you already know the answer?
From what I can tell the protein is in the ribosome and after centrifuging the ribosomes would be at the top of the mixture since they are less dense. Note that organelle density is NOT the same as organelle size.</p>
<p>^yeah, they would be at the top;</p>
<p>though actually, according to Campbells, you would need a rotation that gives a gravitational force of like 100,000g or something in order to separate the ribosomes since they are so small</p>
<p>Top since ribosomes are the least dense!</p>