GCSE Biology - AQA
2.2.2 - Genes
The function of DNA is to store instructions for making proteins. This is very important because every cell needs to make a large number of different proteins in order to function.
DNA contains instructions for making proteins.
A single DNA molecule usually contains instructions for making multiple proteins. Different sections of the DNA molecule contain the instructions for making different proteins. These sections of the DNA molecule are called genes.
A gene is a section of a DNA molecule that contains the instructions for making a particular protein. Another way of saying this is to say that the gene 'codes for' the protein.
A gene is a section of a DNA molecule that codes for a protein. In other words, the gene contains the instructions that the cell follows in order to make the protein.
Within the DNA of an organism there are genes for every protein that the organism produces.
Every protein has a unique shape which allows it to carry out its function. For example, an enzyme has an active site which is shaped to fit its substrates, and a protein which is a receptor for a hormone has a shape which allows it to bind to that hormone.
The unique shape of each protein is a result of the unique sequence of amino acids that make it up. A protein is made by joining together amino acids into a chain which then folds up to form the final shape of the protein. If the amino acid sequence was different, the protein would fold up into a different shape.
When a cell makes a protein, the gene acts as a set of instructions telling the cell how to make the protein. Each gene has a unique sequence for bases which determines the amino acid sequence of the protein that it codes for.
The sequence of bases within a gene determines the sequence of amino acids in the protein that it codes for. This then determines the shape of the protein, which is essential to the protein's function.
Flashcards help you memorise information quickly. Copy each question onto its own flashcard and then write the answer on the other side. Testing yourself on these regularly will enable you to learn much more quickly than just reading and making notes.
What is the function of DNA?
What is a gene?
How does a gene code for a protein?
2.2.3 - Chromosomes and Plasmids
2.2.1 - The Structure of DNA
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