The endomembrane system is the next topic that will be presented concerning the differences between prokaryotes and eukaryotes. No prokaryotic cell has an endomembrane system. However all eukaryotic cells do, so evolution must explain how the endomembrane system evolved.
The endomembrane system is a network of independent organelles that share membranes and work together in what has been described as the cellular import/export business. When one cell makes something that other cells of the organism needs, the endomembrane system exports it. Likewise, when a cell needs to take something into the cell from outside the cell it also uses the endomembrane system to import these.
The endomembrane system is composed of many structures. There is the nuclear membrane, the endoplasmic reticulum, the Golgi apparatus, lysosomes, vacuoles, vesicles and the cell membrane. Each of these ‘parts’ all share the same type of membranes. All of these individual organelles and structures combine to make a single functional unit. All of these have the same structure of the membranes and they merge, combine, interact, move and share components of these membranes in coordinated ways. It is very much like the amazing cytoskeleton of controversy number 23 where components of these systems are constantly changing and interacting.
Each of these parts can be physically separated at times, and at other times are connected to exchange materials. Each of these performs functions of the import and export business. The nuclear membrane contains the DNA and this is made into RNA in the nucleus or ‘brain’ of the cell. The RNA carries the information to make proteins to the endoplasmic reticulum (ER). The function of the ER is like a manufacturing plant for the cell. There are two types of ER. Smooth ER makes and stores fats and steroids, and rough ER makes proteins. These are then sent to the Golgi apparatus which functions like a packaging plant. Once the materials are packaged they need to be transported and this is done by vesicles which merge with the cell membrane to export the materials out of the cell. There are also lysosomes which work in the import business and contain enzymes and chemicals to breakdown materials that are imported into the cell. The last structure is the vacuole which is like a storage facility and can isolate toxic substances or store water.
So the nuclear membrane contains the DNA and RNA, the endoplasmic reticulum does the manufacturing, the golgi apparatus does the packaging, the vesicles do the transportation, the vacuoles do the storage, the lysosomes dispose of the waste, and the cell membrane is the building that houses them all. They all work together in a system which is called the endomembrane system. So what do we know about how the endomembrane system evolved?
George Washington University (where I went to medical school) at the gwu.edu website in the article “Origin of Eukaryotes” summarizes it as “The origins of endoplasmic reticulum, golgi, nuclear membranes, chromosomes and mitosis are not known. A few hypotheses have been proposed but, because these are not based on any actual observations, are mere speculation”. This lack of understanding of the origin of the endomembrane system is confirmed in the journal Cold Spring Harbor Perspectives in Biology in the article, “Missing pieces of an ancient puzzle: evolution of the eukaryotic membrane-trafficking system” where they hope their data will “allow for new insights into the history and forces that shape the evolution of this critical cell biological system”. There is also the article, “Transport and internal organization of membranes: vesicles, membrane networks and GTP-binding proteins” published in the Journal of Cell Science where it is hoped that “Resolving the question of the origin of internal membranes may help us to understand the mechanism of intracellular transport”. Finally, in the Proceedings of the National Academy of Sciences in the article, “Feeling the hidden mechanical forces in lipid bilayer is an original sense” they conclude that “We are now at awe by the sophistication of modern membranes, which house the key energy converters: photosynthesis and oxidative phosphorylation. However, at the most basic level, we are still struggling to understand how physical forces govern various cell biological, genetic, and developmental processes”.
The details of these articles are only understood by experts in these fields. That does not matter for what we are considering here. Do not worry if the terminology and vocabulary is unknown, since it is unknown to most people. The point is that there are so many of these articles that show the experts just don’t know how these critically essential parts of life could possibly exist through evolution. It is a tremendous problem that they cannot explain the origin of any of these many, many vital life sustaining parts of life.
The endomembrane system is found in all eukaryotes and is not in any prokaryotes. It is a complex and interrelated system of separate cellular organelles that have the ability to share their membranes. The origin of any of them can only be understood within the context of the origin of all of them because they all work together.
Evolution cannot be true if there is no origin of the the endomembrane system because it is a necessary condition. Even though it is necessary, it is a published fact in peer reviewed scientific journals that the origin of the endomembrane system is not understood.
You do not need to be a cellular physiologist to understand:
If there is no origin of the endomembrane system, then evolution logically cannot be possible.