Sunday, August 11, 2013

Science Sunday: DNA Replication (Part 2)



Posted by Rebekah

 Please click here for “DNA Replication (Part 1).”



Last time I said that DNA replication in prokaryotes is different from that in eukaryotes. DNA replication in the bacteria Escherichia coli (i.e. E. coli) is often used to exemplify these differences.

Below I briefly summarize these differences.  


First, it is important to note that the E. coli chromosome is circular and only has one origin of replication—this is the case for most other bacteria.   



As expected, replication begins at the origin of replication; hence, forming a replication bubble and two replication forks. Please note that the daughter strand is shown in light green.


Finally, two new daughter DNA molecules are formed. 

DNA Replication—a Closer Look
 
A closer look at DNA replication
In order to facilitate this section, I have made a drawing (see above) of only some of the many enzymes and proteins involved in DNA replication. Please note that, as implied in the previous post, DNA synthesis is no easy feat. Not surprisingly, one finds that there is still much to learn about this astounding process.

Much of the current knowledge of DNA replication comes from bacterial DNA, so my goal is to concentrate primarily on bacteria. Please study the drawing above carefully (which, by the way is conveniently color coded), as it will come in handy for subsequent posts.     
 
To be continued...

                                                            References 

Reece, Jane B., et al. Campbell Biology. 9th Global Edition. “Many Proteins Work Together in DNA Replication and Repair.” Boston: Pearson, 2011. 357-365. Print.


WARNING: Due to several reasons, I do NOT recommend Campbell Biology for your homeschool. However, due largely impart to its prevalent use in colleges and universities (and even Wikipedia), I chose to use it as a reference.