Biology 6.1-DNA 1

• DNA stands for Deoxyribonucleic Acid
• DNA determines which proteins a cell produces and therefore what kind of cell it will be.
• DNA is the chemical all genetic material is made up of.
• DNA is a polymer.
• DNA is made up of two strands and forms a double helix.
• If all DNA was unravelled from a single cell, it would be more than 2 m long.
• DNA is seperated into 46 different sections so it can fit into the nucleus.
• A chromosome is a section of DNA.
• There are 23 different types of chromosomes.
• There are 23 chromosome pairs in a human cell.
• The 23rd chromosome pair have the sex chromosomes.
• A gene is a small section of DNA ( a small segment of a chromosome).
• A gene codes for a specific type of protein.
• Genes code for a sequence of amino acids (which make up proteins).
• There are only 20 different types of amino acids.
• The Genome is the entire set of genetic material in an organism.
• Twins have the same genome.
• Scientists know the complete human genome (the entire code our DNA holds).
• Knowing the complete human genome means that scientists can identify the genes linked to certain types of diseases.
• Some genes cause a disease, therefore it will be inherited (from parents or ancestors).
• Some genes increase the risk of a disease e.g BRCA genes increase the risk of Breast Cancer.
• Knowing the complete human genome means that doctors can choose more effective treatments.
• Knowing the complete human genome means that scientists can develop better treatments.
• Knowing the complete human genome means that we can trace migrations of ancestors.
• All humans share most of their genome but small differences between different populations can tell us when they separated.