AQA Biology Unit 2 Section 2 : Genetics

DNA

DNA is made up of nucleotides that contain a sugar, phosphate and a base

• DNA is a polynucleotide - many nucleotides
• Each nucleotide is made from a pentose sugar, phosphate group and nitrogenous base
• The sugar is a deoxyribose sugar
• Each nucleotide has the same sugar and phosphate. the base on each nucleotide can vary though
• These are A,T,C,G

Two polynucleotides join together to form a double helix

• DNA nucleotides join together to form polynucleotide strands
• This form the sugar-phosphate backbone
• The two strands are joined by hydrogen bonds at the bases
• Each base can only join with one particular partner - specific base pairing
• The strands wind up to form a double helix

DNA's structure makes it good at its job

• DNA contain genetic information - all the information needed to grow and develop
• DNA can be coiled up tightly allowing it to fit into a small space in the cell nucleus
• DNA molecules have a paired structure, which makes it much easier to copy itself. Self replication. This is important for passing information from generation to generation
• The double helix means DNA is very…