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DNA Structure and Replication

DNA Structure and Replication

Introduction: DNA is the molecule that provides the blueprint for all the traits an organism expresses. It is made of a sugar (called deoxyribose) backbone, phosphate groups, and individual nitrogen bases that, when put into a particular order, produce proteins that express traits. Since DNA is found within every cell in an organism's body, it needs to be copied every time a cell duplicates.

DNA has a structure called a double helix. As seen in the image below, it looks a lot like a twisted ladder. The nitrogen bases are held together by hydrogen bonds. When it is time to replicate itself, an enzyme called DNA helicase breaks down those bonds and causes the strands to unzip. This exposes the nitrogen bases. At the same time, there are free-floating nucleotides in the nucleus that come along and attach themselves to their complement. Another enzyme, DNA polymerase, attaches these new nucleotides to create two new strands of DNA.


Directions for this Lesson: Answer the questions about DNA and then watch the video to learn more about its structure and process of replication.

Required Video: