The structure of DNA

• The nucleus contains chromosomes, these are made from the molecule DNA.
• There are 46 chromosomes in every human body cell and they are arranged in pairs. (these are called homologous pairs)
• Each pair consists of one maternal chromosome and one paternal chromosome.
• There are 23 pairs in humans. Each individual chromosome is a long length of DNA, some sections of DNA are the instructions to build proteins; these are genes.
• Genes are short lengths of DNA which code for specific amino acids
• Interphase is the longest phase, during which DNA replicates to form two identical copies.
• The cell cycle is the series of events that occur between one cell division and another.
• DNA synthesis occurs during interphase when DNA replication takes place.