Quote from: TheBadger on July 29, 2013, 04:39:18 AMHow do you get DNA without a cell membrane? And how do you get a cell membrane without a DNA?You cant. You never will. It has never happened....
I had written an answer for this question and I lost it. This time I am going to write it in an editor and then copy it to the browser.
Don't confuse the words "random" and "chaos". Really, very little (if any) truly random things happen. We only call them random because we can't explain why or how they happened when they did. Chaos is a better word for what we are talking about. But let's not misunderstand that idea either.
For example, say a creationist tells you that someone pours two substances into a jar and mixes them up. Then he asks "What are the chances that they will, by random chance, separate themselves so that one substance goes to the top and the other goes to the bottom. He does it, and within seconds, this very unlikely thing happens within seconds before his very eyes! "Uh never mind" he says and walks away embarrassed. You see the two substances that were mixed are oil and water. No this "random" separation doesn't seem like such a miracle now, does it? We then have to conclude that what is happening in the jar does have some chaos going on but the separation of the two substances was caused by something other than random chance or chaos but under the control of the environment and by the substances' physical properties.
Now let's ask what are the chances that we will get a membrane if we pour a substance into some water. If you have a bunch of molecules that are polar at one end and non-polar at the other, they automatically line themselves up so that the polar ends are together and the non-polar ends are together. They spontaneously form a membrane! Yes, it has been done many times in the lab. For an example that you should be familiar with from your childhood, what is the chance that if you dip a loop into some soapy water and pull it out and blow that you will get a bubble? Pretty darn good. So good in fact that you can get one almost every time with the right soap concentration and mechanical motion. This is basically a membrane in air. The same kind of thing happens in water, believe it or not. So it turns out that, with the right chemicals in solution (no life) membranes form all by themselves easily and quickly. So your membrane forming probabilities are way off reality.
So your question has boiled down to "How likely is DNA to form?". The cell membrane part is a non-issue. Let's take a look at BSE (Bovine Spongiform Encephalopathy). This is a very interesting disorder that comes from eating raw mammal brain. It is not an infection because the agent is only a protein that can't behave in such a way that you would call it "life". A virus is somewhere in between and we will only talk about that if need be. So how does the BSE protein work? As you may already know, proteins are long chains of amino acids much in the same way that DNA is (except that DNA is long chains of nucleic acids). After they are produced in ribosomes, they don't have their normal activity until they fold a certain way (often with the help of enzymes that are there to do this) and have their necessary inclusions such as iron or other ions that are dissolved in the solution. When they are folded in a specific way (hydrated with water), they take on their special activity. The BSE protein is the same one that you have lots of in your brain, except those are folded differently than the BSE protein. So what is the BSE's activity? It basically goes around and finds the proteins in your brain that are folded correctly and it refolds them to be like itself. Now ask yourself, "Did this protein reproduce?" Certainly not, it just converted something similar into something just like itself.
Back 2 Billion years ago, the Earth's environment was vastly different than it is today. Thanks to photosynthetic plants, our atmosphere is an oxidiizing atmosphere. But before these became common, the Earth's atmosphere and oceans were highly reducing environments. In an oxidizing environment, oxygen is common and "free" while organic molecules are rare and "costly". They are food and bacteria scarf them up. But in 3 Billion BC Earth, organic molecules were "free" (i.e. everywhere) and oxygen was rare. There were no bacteria to scarf them up and no oxygen to burn them anyway. This "Promordial Soup" was very different from what we see today. And just because there was no life as you would recognize it doesn't mean that they weren't all mixed in together, reacting with each other and the sunlight. This soup had untold competing reactions going on with predominant proteins converting other proteins and reacting with other chemicals on a massive scale. When resources are used up to produce a substance those resources are taken away from other processes that would convert them to something else. Yes, this is competition and we don't even have life yet!!!!!!!
So chemical systems that didn't even need DNA were competing with one another. Certain proteins (and even certain groups of proteins) could isolate themselves in the membranes we talked about that are so easily formed. This isolated them from other processes that promoting their own chemical systems. One chemical system won out over another chemical system and there was extinction and there wasn't even life yet! It is well known that ribosomes can replicate RNA and produce proteins from RNA so DNA is not even necessary. In our BSE example, all we needed was one protein and the right resources and it could make more of itself. The simplest forms of life you would never have recognized as life, yet, with the fairly sophisticated resources that were plentiful at their disposal, they could make more of themselves.
Keep in mind that the life as we know it has only been around for half a billion years. The Earth is four billion years older than this. And with an environment of primordial soup, reproduction, competition, consumption of resources and the building of complex systems can happen without life. Also, keep in mind, because modern life did not exist, there were no bacteria to consume the sugars and other molecules that don't last very long in present day Earth because some organism consumes them. But since there weren't any in primordial Earth, these molecules were all over the place. The competing complex chemical processes evolved into more sophisticated ones even before they could be considered to be life. Perhaps trillions (and many more) changes took place in the competing systems as they got to be more sophisticated. After tens of millions of years, the systems got so sophisticated that some people might even call them life forms while others would not. It was the same way with the evolution of species later on. When did life begin? I don't know. It depends on your definition. The line between life and primordial soup is a very broad one indeed.
The common perception that chemicals (both organic and otherwise) just sit around and do nothing until an organism finds them and eats them is completely wrong. Think of the chemicals like people where a government organizes them and encourages them to work toward some common goal. Even without a government, people do things on their own. But what they do or the way they do it can be greatly influenced by a system that we call organization or a government. Indeed, government systems do compete, reproduce and go extinct. Some people counter the government and often the government finds a way to eliminate them.
Related to this is, it is common knowledge, that higher life forms (eukaryotes) are actually an obligate commensalism between a host and an invading organism, that at one time was a parasite. But the two (or more) species have become so dependent on eachother that they will die without their symbiotic relationship. Our cells have organelles that came from different species invading our ancestors' cells. There are mitochondria (that have their own DNA by the way), chloroplasts (in higher green plants) etc.
So it turns out that the DNA in the nucleus of your own cells does not completely describe how to make another human in two major ways. First, your body needs complex molecules that were built by the enzymes and associated processing of other organisms such as plants. Your nuclear DNA certainly doesn't know how to make those from scratch. That is why you have to consume them. "Vitamins" and proteins among others are prime examples. So, in a way, we could claim that corn DNA (just as an example) is also human DNA because we eat the products of corn and incorporate its complex structures into our bodies. For the same token, other herbivores and predators that eat those herbivores could also claim that corn is part of their genome. Second, your nuclear DNA does not contain information on how to make many of the organelles in your body. They have to reproduce themselves with their own DNA or RNA (or yet to be discovered mechanism of self replication). So when you hear someone in a documentary tell you that your nuclear DNA knows how to build everything in your body you can smile and know they are ignorant.