DNA replication.

So DNA carries your genetic information, is made of a double helix with hydrogen-bonded nitrogenous bases, a 5-carbon sugar and a phosphate group... how do they come to be? how does EVERY DNA molecule come to be an exact replica of the one before?

DNA makes a copy of itself in the nucleus before cells divide to ensure continuity of hereditary traits

The textbook I have been assigned (Inquiry into Life by Sylvia S. Mader 8th edition) shows us three steps to DNA replication (I know there are a few more, and much more detail, but for the purposes of this course, we learn the 3 simple steps)



1. Unwinding: The two strands that make DNA unwind and 'unzip' to become two phosphate-sugar strands (temporarily) thanks to the enzyme DNA Helicase.

Oh man... anyhow, Helicase causes the hydrogen bonds to break. We now have two separate strands with single bases.


2. Complementary bases pair with the free nucleotides. Free floating nucleotides are always floating in the nucleus. They now pair with the nucleotides that have been unzipped.


3. Joining: DNA Polymerase joins the paired nucleotides and they are sealed together form two new strands of DNA.


So there are now two newish strands of DNA. Each helix that has just been created contains one strand of the old (parental) helix and one strand of the new (daughter) helix. In this way, DNA replication is known to be semiconservative. 

In this way, the double helix of DNA is handy- the old strand is used as a template during replication to ensure accuracy.

Loved this video... the process is easy to understand and it's cute. A bit more information than is needed in my class at present but who cares? ;) it's a good video. 

Important terms from my flashcards:

1. DNA Polymerase~ an enzyme that joins nucleotides to their complementary bases during DNA replication


2. DNA Helicase~ An enzyme that causes the DNA molecule to unzip and unwind.

3. Semiconservative: DNA replication is known as semiconservative because the parental strand is conserved when it separates to join with new nucleotides forming daughter strands and a new helix.