About DNA

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  • Created by: Sonia
  • Created on: 24-04-09 18:45


DNA is made from 2 strands wound into double helix.

1 strand called coding strand, this strand carries the carries the code for specific features. The other strand does not carry any code and is called the non-coding strand.

Structure of DNA

  • made up of 2 strands into double helix
  • made up of many strands called nucleotides, it is a polynucleotide
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Nucleotide structure

Made up of:-

  • Organic base (adenine, thymine, cytosine or guanine)
  • Molecule of deoxyribose
  • Phosphate group

A nucleotide containig th base cytosine always paired with one containing guanine. This is the base-pairing rule.

Adenine and thymine are said to be complementary bases, as are cytosine and guanine.

2 strands are said to be anti-parallel. The start or top of one strand is paired with the end or bottom of the other.

Covalent bonds holding the nucleotides together in each strand are stronger than the hydrogen bonds holding the 2 strands together. Strong covalent bonds ensure that the structure of each strand is stable.

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Function of DNA

DNA is resonsible for passing genetic information from cell to cell and generation to generation.

There's 3.2 billion base pairs in the DNA of a typical mammalian cell

DNA is very stable, and its two separate strands are joined only with hydrogen bonds, which allows them to separate during DNA replication.

DNA is extremely large molecule and therefore carries an immense amount of genetic information.

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