Topic 2 - Nucleic Acids

• Individual nucleotides are made up of three individual components - a pentose sugar (ribose or deoxyribose), a phosphate group and a nitrogen-containing organic base (adenine, thymine, cytosine and guanine).
• In a nucleotide, the pentose sugar, phosphate group and nitrogen-containing base are joined in a condensation reaction to form a mononucleotide.
• Two mononucleotides can be joined to form a dinucleotide as a result of a condensation reaction between the deoxyribose sugar of one mononucleotide and the phosphate group of another, forming a phosphodiester bond.
• The continued linking of mononucleotides forms a long chain known as a polynucleotide.
• Cell division occurs in two main stages: nuclear division and cytokinesis.
• Nuclear division is the process by which the nucleus divides. There are two main types of nuclear division - mitosis and meiosis.
• Cytokinesis follows nuclear division, and is the process by which the entire cell divides.
• Before a nucleus divides, its DNA must replicated to ensure that all the daughter cells have the genetic information to produce the enzymes and other proteins that they need.