One of the biggest changes between prokaryotic and eukaryotic cells is the fact that instead of only one intracellular space they are now divided and has membrane bound organelles. Why would eukaryotic cells go through all the difficulty to become compartmentalised? It obviously must have held some advantages which outweighed the trouble. In this essay the advantages and resulting problems of specialised compartments in eukaryotic cells will be discussed.
First we will look at the advantages gained. There are many including: the increase in total membrane area, the fact that some necessary proteins for metabolic processes can now be built into the organelle’s membranes and membranes can ...view middle of the document...
It also controls when and which proteins have access to the chromosomes.
In this we can see that where prokaryotes had to constrain themselves to a single function and the environment influenced what this function was, eukaryotes can now perform multiple opposing functions at the same time independent of their environment. This is thanks to the fact that the organelles membranes provide the surface where essential metabolic processes occur and some important enzymatic proteins are built into the organelle membranes.
But what problems needed to be overcame to accomplish this compartmentalisation? The biggest and main problem was transport across the membranes. How was this problem overcome?
Many cells take up molecules through the process called receptor-mediated endocytosis: a protein or larger complex initially binds to a receptor on the cell surface. After the protein is bound, specialized proteins act to cause the membrane in the vicinity of the bound protein to invaginate. The invaginated membrane eventually breaks off and fuses to form a vesicle. (Extract from Berg, J. M. , Tymoczko, J. L. , and Stryer,L. Biochemistry 5th edition) The only disadvantage of this path is that it is also available for viruses and toxins to enter a cell.
Other solutions for this problem is membrane proteins. There are different proteins such as: transport-, recognition-, adhesion-, and receptor proteins. They allow substances to move in and out of cells, the body to recognise its own cells, stick cells together, bind molecules to the outside of the cell...