DNA Structure: I thought that maybe I would make some clarifications on the structure of the DNA. It is comprised of sugar phosphate groups and the nitrogen bases and the chains of DNA are anti parallel running from 3' to 5'. I thought this part necessary for a review. This way it will be fresh in your mind.
In this I asked why the structure (DNA) would come together. By that I meant to come together and form chromosomes. We have 23 pairs of chromosomes in every cell in our bodies. All they are is DNA. But the DNA comes together to form this structure. Now does anyone know why it would do just that? Why would it come together and make a structure like so? Yes it helps with mitosis, but what told it to do so? Why is DNA programed to do this? (not to mention what tells the DNA what to tell the cell?) The cell reads the DNA within the Chromosomes to know how to do specific things, such as how to form, and perform it's day to day functions properly.Gabrielman wrote:Why would these structures come together? And better yet, why would they then be the instructions for all of the cells in our bodies on how they should operate? Why would they be alive? What would prompt this? I have included the picture and what I have to show you the basic, very basic complexity of our base building blocks of life. Without DNA and RNA, life isn't possible. Period.
Above is an image of a Chromosome. Note the X shape it seems to take, all on it's own to ready itself for cell division. X shape they take helps with cell division, and then, when the cell has to remake everything that it has. Now cell division is called mitosis. Now before I go on, I want to let you know why I am getting into cell division before explaining the rest of the cell. This is because of how complex the division is, cells need to reproduce, they need that ability to pass on genes. Mitosis is how cells do this. Without some form of reproduction, well there is no evolution, there is not passing on genes, there are not mutations to speak of. Even if the simplest organism when life began started only with RNA, it would still have to have some form of reproduction in order to pass on it's genes and create more life of earth. But how did that happen? How did the first life arise, and further more, how did it already have genes put together in such a manner as RNA and DNA, and how did it pass on those genes. The aim of this thread is to show you how complex and complicated things really are, and my hope is that by the time this all sinks in, you will have grasped how there could be no life without someone intelligent guiding it. Kristoffer, this is for you.
Now before I go on with mitosis fully, let me first explain how the DNA prepares itself for cell division and replication. DNA must replicate in order for a new cell to have the same stuff as the old cell. How it does this is using enzymes called DNA Polymerase, DNA Ligase, and DNA Helicase. These help to "unzip", duplicate, and "re-zip" the DNA. Now for each new strand of DNA we can say they are Semi-conservative Replications because they are made of one old half and one new half of DNA. Helicase binds to a specific site on the DNA called the origin replication complex. (this makes one wonder that if all living things started with at the very least RNA, how would it reproduce when now a days it requires such a complex process.) Then it "unwinds" the DNA by breaking down the hydrogen bonds between the DNA strands. Are you following me so far? Now at this point the DNA is split open in a replication fork, with the 3' end and the 5' end, the leading strand and the lagging strand.
Taking a quick pause, I am not sure if I explained what the 3' and 5' ends were before, so I will do so now. The 5' is the phosphate end of the DNA and the 3' is the Hydroxyl group. This may be needed info for you later, but it is also important to know because it pertains to the structure of the backbone of our DNA.
Anyway, on to mitosis. The DNA Polymerase adds dNTP's (deoxyribonucleotide-triphosphates) to the 3' end of the DNA, that is the leading strand and is continuous. This is how one copy of DNA is made from the 3' end, but the 5' end is a bit more complex, as it is a lagging end with starts and stops. But first take a look at the image below:
(the source of this picture was obscure so if there is anything wrong with it let me know, i.e. like it needs removed)
The other strand of DNA is the lagging strand that stops and start, it is therefore discontinuous. Every time it starts again it gets a new primer. As you can see these are called Okazaki Fragments and they were discovered by Reiji Okazaki.
That being said, that is how the DNA prepares for mitosis. This happens so that there can be the same DNA in each new cell. However the lagging strand is where more errors are likely to occur, this is where genetic mutation can take place (as well as other places, but for now we are talking about this). These become permanent and can be passed on from generation to generation, but not always, as we will see when I cover reproductive mutations, new ones can snuff out the old ones. It would be good to make note of the fact that, with as often as mutations occur, and with the percent of how many would be detrimental and not helpful, that one would think that we would have been wiped out to begin with. However it is also good to note that the mutations are more than likely nothing more than just a slight change in how you look. As you do not look like your parents. So small changes within a species, but not enough to be evolution in the sense of what you are talking about. It is also worth taking note that the DNA polymerase scans and proofreads the new DNA while it is being made and fixes mistakes that it finds. However it only reduces the number of mistakes by a very small amount, so it is not accurate enough. This comes into play later on in reproduction, as these will be passed on.
Now on to the rest of mitosis. Now that the DNA has been replicated, you have enough to create a whole new cell. There are four stages to mitosis and they are Prophase, Metaphase, Anaphase, and Telophase. Now that we have the replicated DNA they have to come together to form the chromosomes as we have seen above, as at this point they are still just loose coiled DNA in a chromatin state, which is simply the state they are in before becoming chromosomes, and I can explain that more if need be. Now the nuclear membrane and the nucleolus break down and expose the chromosomes. In this stage something called the spindle apparatus comes into play. It attaches spindle fibers to the chromosomes after it has migrated to two opposite sides of the cell, and aligns the chromosomes in the middle of the cell. At this point the spindle fibers begin to retract and pull apart the chromosomes. During this stage the worst kind of mistake as far as mutation can occur. The spindle fibers may break taking only part of the chromosomes with them, or it may loose it all together and the whole of the chromosome goes to the other cell. In a case like this the one cell has too many to function properly and the other has too few. Imagine it like you and a friend both need the same books for an upcoming collage exam. You both order them from the same place, and at the same time. Now imagine that they pack the books up in bags for you both, but one of them gets mislabeled. Your friend get all the books he needs, and a bag of books that you would need as well. When you pick up your order, you are missing your set, and therefore are missing vital information to pass the exam, while your friend has more than he needs. He can just toss out the extras and not think anything of it. Giving you the books he has as extra is also something he could do, but for a cell that is not an option. Now one cells has what it needs and then some and the other does not have what it needs to succeed.
In this we can see how mutations can be very detrimental, more often than helpful. We can also see the complex properties of how things first begin to reproduce. With that in mind, it makes one think. How could the most basic life forms survive to evolve? To begin with the chances of them getting a good mutation are slim, and the chances that they would have all of the ability to reproduce are even less so. What's more is that the DNA or RNA they may have already has all of that encoded in on it, but how did that encoding get there? And why is it made in such a way? I want to add more but this is long enough as it is. So let me say why I am getting at the basics right now. I think it is vital for you to know just how complex and complicated life is at a very basic level. And how unlikely that is for it form on it's own. The very point of this thread is to discuss that complexity, and show how it must have been designed by an intelligent source, that being God. We will get more complex as we go, and I have not given all the information yet as I think that it is vital you have the basics down in your mind first. We will go on from here Kristoffer, and explore the amazing world that God has created for us and how complex it really is.
God Bless, and more to come.
EDIT: Main Site Articles On Biological Design