DNA replication, how is it best explained, through natural mechanisms, or a intelligent cause ? elshamah.heavenforum.org/t1849-dna-replication-how-is-it-best-explained-through-natural-mechanisms-or-a-intelligent-cause#3090 nobelprize.org/educational/medicine/dna/a/replication/ Replication Before a cell divides What is the driving force to make the cell divide ? Why at all did dividing start ? it has to replicate its DNA so that the daughter cell receives a copy of the genome. The DNA helix consists of two complementary DNA strands. Why at all did a complementary strand arise ? Therefore, each of the two strands serves as a template for the construction of the other strand. Under normal conditions the DNA is packed into a compact structure called chromatin. To be able to replicate, the cell has to unfold and unwind the DNA, What is the reason that it started to unwind ? and also has to separate the two strands from each other. The cell has a complex machinery to perform these tasks. How did this machinery arise ? What was the force behind it ? What is the origin of the information to make this machinery ? When it is time to replicate, special initiator proteins attach to the DNA at regions called replication origins. For what reasos did these special initiator proteins arise ? Where came the information come from to encode these proteins ? These regions are characterised by a weak bond between the two DNA strands. How did this bond arise ? There are around 10,000 replication origins on the DNA in a cell; this arrangement increases the rate of replication tremendously. The initiator proteins pry the two strands apart How did these proteins become able to pry the two strands apart ? and a small gap is created at the replication origin. Once the strands are separated another group of proteins, that carry out the DNA replication, attaches and go to work. How did these other group of proteins start to be able to attach at the right position, and go to work ? This group of proteins includes helicase, which serves as an unzipper by breaking the bonds between the two DNA strands. elshamah.heavenforum.org/t1438-hexameric-helicases en.wikipedia.org/wiki/Helicase The hexameric helicases are ubiquitous proteins (related enzymes are found on both sides of bacterial-archaean divide) involved in unwinding double-stranded DNA and RNA. we can see its structure here : ks.uiuc.edu/images/ofmonth/2010-12a/helicase_highlight_1200.png In this youtube video its called a fascinating protein machine . evolutionnews.org/2013/02/unwinding_the_d_1069371.html this is a highly organized, sofisticated and orchestrated movement, like a roboter,executing a specific task: youtube/watch?v=Oy1RGlT0vv0 In order to be able to unwind the dna strand, the initial opening of the double helix (at the origin of replication) is performed by an initiator protein. How did chance, physical necessity, or natural selection know a initiator protein would be needed, and how it would have to be , and where employd ? The helicase rotational speed of up to 10,000 rotations per minute !!!!! How astonishing and marvellous . This unzipping takes place in both directions from the replication origins, creating a replication bubble. The replication is therefore said to be bi-directional. How did they start and know the need to be bidirectional ? Once the two strands are separated a small piece of RNA, called an RNA primer en.wikipedia.org/wiki/Primer_%28molecular_biology%29 , is attached to the DNA by an enzyme called DNA primase. https://jkweb.berkeley.edu/external/pdb/2000/primase/primase.html Primases synthesize short RNA strands on single-stranded DNA templates, thereby generating the hybrid duplexes required for the initiation of synthesis by DNA polymerases. These primers are the beginnings of all new DNA chains since the enzyme responsible for the copying of the DNA, DNA polymerase, can not start from scratch. It is a self-correcting enzyme and copies the DNA template with remarkable fidelity. How did it learn to self correct itself ? The DNA polymerase can only read in the 3 to 5 direction. This gives rise to some trouble since the two strands of the DNA are antiparallel. On the upper strand which runs from 3 to 5, nucleotide polymerisation can take place continuously without any problems. This strand is called the leading strand. But how does the polymerase copy the other strand then when it runs in the opposite direction, from 5 to 3? On this so called lagging strand the polymerase produces short DNA fragments, called okazaki fragments, by using a backstitching technique. How and why did it begin the backstitiching technique ? These lagging strand fragments are primed by short RNA primers and are subsequently erased and replaced by DNA.
Posted on: Sat, 02 Aug 2014 18:29:35 +0000
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