Functions of Enzymes in DNA Replication
- Topoisomerase - relaxes the supercoiled DNA
- Helicase - Catalyzes the breaking of hydrogen bonds between base pairs, and unwinds the double helix into a single strand DNA
- Single Strand DNA binding (SSB) - Stabilizes single-stranded DNA
- Primase - Catalyzes the synthesis of the RNA primer
- DNA polymerase I - erases the RNA primers and fills in the gaps with DNA
- DNA polymerase III - Extends the leading strand, proof reads and repairs
- DNA Ligase - Joins the 3' and 5' ends of the DNA strands into a continuous strand
- DNA gryase - supercoils the DNA
Double Helix and it's Anti-parallel Orientation
Two strands of DNA have the same helical geometry however base pairing holds the strands together with opposite polarity. This means that the 5' end of a strand is paired with the base of the end of the other strand 3'. This is called anti-parallel orientation, the consequence that adenine and thymine pair with each other and guanine and cytosine pair with each other. You can see this depiction in the image to the left.
DNA Replication - Eukaryotes versus Prokaryotes
Eukaryotes
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Prokaryotes
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