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DNA Structure and Function

Biology (Year 12)


Content Writers

Christian Bien - Bloom Photo (1).jpeg

Ben Whitten

What is DNA?

Image: DNA double helix horizontal image, Image by Jerome Walker, Sourced Under a Creative Commons 4.0 License from Wiki Commons DNA stands for deoxyribonucleic acid, and at its core, it is the code for all life! The structure of DNA is further covered on another page, but it is key to know that there are four types of nitrogenous bases found in DNA. These include;

  • Adenine (A)

  • Thymine (T)

  • Cytosine (C)

  • Guanine (G)

DNA follows a complementary base pairing rule. This is the phenomenon where;

  • Adenine will always bond with Thymine (A with T)

  • Cytosine will always pair with Guanine (C with G)

The bonds which are formed between these bases are hydrogen bonds, where adenine and thymine have 2 hydrogen bonds and cytosine and guanine have 3 hydrogen bonds.

Where is DNA found?

The location of DNA varies with the type of cell. In a eukaryotic cell, DNA occurs bound to proteins in chromosomes within the nucleus. Linear DNA becomes tightly coiled to form the chromosomes. It is important to note that DNA is enclosed in a nuclear membrane to protect its interior. In a prokaryotic cell, DNA is found in an unbound circular form in the nucleoid region of the cytosol, which is not bound by a nuclear membrane. This type of DNA is found in organelles like the chloroplast and the mitochondria and is also found in prokaryotic organisms like protists.


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