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Structure of RNA and DNA - Coggle Diagram
Structure of RNA and DNA
Nucleotide Structure
Nucleic acids are a group of the most important molecules of which the best known are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).
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A nucleotide contains a pentose sugar, a phosphate group and a nitrogen-containing organic base. These are cytosine (C), thymine (T), uracil (U), adenine (A) and guanine (G).
The pentose sugar, phosphate group and organic base are joined, as a result of condensation reactions, to form a mononucleotide.
Two mononucleotides joined forms a dinucleotide. There is a condensation reaction between the deoxyribose
sugar on one nucleotide and the phosphate group of another.
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DNA Structure
A nucleotide in RNA contains a pentose sugar, a phosphate group and a nitrogen-containing organic base. These are cytosine (C), thymine (T), adenine (A) and guanine (G).
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There are two antiparallel DNA strands held together by hydrogen bonding between complementary bases.
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The pentose sugars and phosphates link by phosphodiester bonds which is the sugar-phosphate backbone of the DNA double helix.
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Adenine and Thymine pair up, whilst Guanine and Cytosine pair up.
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The phosphodiester backbone protects the more chemically reactive organic bases inside the double helix.
Hydrogen bonds link the organic base pairs forming bridges (rungs) between the phosphodiester uprights. As there are three hydrogen bonds between cytosine and guanine, the higher the proportion of C - G pairings. the more stable the DNA molecule.
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DNA was discovered by James Watson and Francis Crick, after previous work carried out by Rosalind Franklin. X-rays were used to understand the physical structure of the DNA molecule.
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