BRAINCAKEPhosphodiester Bonds
Nucleotides are joined into a polynucleotide chain by phosphodiester bonds. A phosphodiester bond forms in a condensation reaction between the phosphate group attached to carbon 5 of one nucleotide's sugar and the hydroxyl (OH) group on carbon 3 of the sugar of the next nucleotide. One molecule of water is released for each bond formed.
The name describes the bond: one phosphate group linked by two ester bonds ("di-ester") to two sugars.
Repeated phosphodiester bonds produce the sugar-phosphate backbone. The chain therefore has two different ends: a 5' end with a free phosphate and a 3' end with a free OH group. New nucleotides are always added to the 3' end.
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Key terms in this lesson
- dna polymerase
- An enzyme that joins nucleotides by forming phosphodiester bonds, synthesising a new strand of DNA using a template strand.
More in DNA, Genes and Protein Synthesis
- Nucleotides
- ATP
- Nucleic Acids
- Complementary Base Pairing
- Evidence for Semi-Conservative DNA Replication
- DNA Replication
- The Genetic Code
- Types of RNA
All 20 lessons in DNA, Genes and Protein Synthesis · All Edexcel AS-level Biology topics