DNA:Structure- The Double Helix

DNA:Structure- The Double Helix

Author: Aaron Mullally

This lesson will examine the structure of DNA as being in the form of a double helix composed of nucleotides.

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The Double Helix

Video Images: Double Helix image, Creative Commons: http://en.wikipedia.org/wiki/File:DNA_Structure%2BKey%2BLabelled.pn_NoBB.png; Nucleotides, Public Domain: http://en.wikipedia.org/w/index.php?title=File:Nucleotides_1.svg&page=1; GC DNA Base Pair image, Public Domain: http://en.wikipedia.org/wiki/File:GC_DNA_base_pair.svg; AT DNA Base Pair, Public Domain: http://en.wikipedia.org/wiki/File:GC_DNA_base_pair.svg; DNA Chemical Structure, Creative Commons: http://en.wikipedia.org/wiki/File:DNA_chemical_structure.svg

Source: Aaron M

  • Nucleotide

    Organic molecules that consist of a 5 carbon sugar (ribose in the case of RNA, and deoxyribose in the case of DNA), a phosphate group and a nitrogenous base; nucleotides are the building blocks of nucleic acids (DNA & RNA).

  • Adenine (A)

    A nucleotide building block of DNA and RNA, adenine is classified as a purine and complements thymine (T) in DNA and uracil (U) in RNA.

  • Thymine (T)

    A nucleotide building block of DNA, thymine is classified as a pyrimidine and complements adenine (A) in DNA; thymine is not found in RNA.

  • Guanine (G)

    A nucleotide building block of DNA and RNA, guanine is classified as a purine and complements cytosine (C) in DNA and RNA.

  • Cytosine (C)

    A nucleotide building block of DNA and RNA, it is classified as a pyrimidine and complements guanine (G) in DNA and RNA.

  • Base Pair

    The way that nucleotides interact with one another, A bonds with T and C bonds with G in DNA, while C bonds with G and A bonds with U (uracil) in RNA. The sequence of base pairs creates the genetic code that is transcribed and translated into proteins.

  • Gene

    A segment of DNA that codes for a specific protein, genes are a sequence of nucleotides.

  • Nucleotide Sequence

    The arrangement of nucleotides that form genes in strands of DNA.

  • Double Helix

    The shape of the DNA molecule, often times is referred to as the “twisted ladder” and is the title to the book about Watson & Crick's discovery of DNA's structure.