Friday, August 22, 2008

Helicase


The DNA molecule as seen in my previous entry (and at DNA label below) is undergoing reproduction. There I showed the first molecule which affects the DNA to prepare it for the process of replication. Now we come to another molecule, called a helicase. These take apart the pairs of nucleotide units which make up the DNA. Above and at the link is a picture of one from Swiss-Model Repository from a Cyanobacterial species. This molecule is made of 773 amino acids, as reported in the research reference in Uniprot Q8DG65. To remind you, there are 20 types of amino acids in proteins, as opposed to hundreds found throughout nature. I am adding pictures of the 20. They are made of atoms like Oxygen, hydrogen and nitrogen. The corners of the lines are understood to have the atom Carbon. The Amino Acid--Creationwiki link at right takes you to a better view if you want it.






These are the units which make up the proteins. There were over 900 amino acids in the first molecule we needed to loosen up the DNA so it would be ready to replicate. This molecule with over 700 amino acids is needed to take apart the DNA so it can be copied to make more cells and organisms. The amino acids have to be in enough of a specific order to allow for the protein to form the way it should. Some of the amino acids may be substituted by a limited amount of others, since there are several groups which have similar properties. But experimentally, some amino acid placements have been found to be absolutely necessary or a protein will not work. Just one difference will completely leave the protein without function.

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