DNA and Protein Production PDF

DNA and the production of proteins DNA carries the genetic information in the cells of all living organisms. It contains codes for the assembly of amino acids into all the proteins required in the body Structure and function of deoxyribonucleic acid (DNA) Deoxyribonucleic acid (DNA) is the informati...

DNA and the production of proteins DNA carries the genetic information in the cells of all living organisms. It contains codes for the assembly of amino acids into all the proteins required in the body Structure and function of deoxyribonucleic acid (DNA) Deoxyribonucleic acid (DNA) is the information-carrying molecule found in all living organisms. In most animal, plant and fungal cells DNA is stored in the nucleus coiled up in thread-like structures called chromosomes. The nucleus of one of your skin cells contains about two metres of DNA, so a chromosome is a very large molecule compacted into a very small space. The information DNA contains is the instructions that the cell uses to make proteins. Proteins play a big part in determining the characteristics of specialised cells and whole organisms. Your eye colour, muscle mass, height and even your ability to learn new skills all result from the activity of specific proteins. The building blocks of DNA are called nucleotides. There are four different types of nucleotide. The part of a nucleotide that can make it different from others is called the base. The four DNA bases are adenine, thymine, cytosine and guanine. These base names are abbreviated to A, T, C and G. 1 Nucleotides are linked together to form strands. DNA consists of two strands of nucleotides twisted around each other to form a shape called a double helix. The two strands are held together by weak bonds between pairs of bases. Only certain pairs of bases have complementary shapes that let them form bonds with each other to make the double helix. Base A bonds with base T and base G bonds with base C. These are complementary. Genetic information and the genetic code The sequence of bases in a DNA molecule can determine the order of amino acids in a protein molecule. Groups of three bases called triplets represent different amino acids. This is the basis of the genetic code. A sequence of bases (genetic information) on DNA that codes for a protein is called a gene. 2 Messengery RNA (mRNA) In animal, plant and fungal cells, the instructions for making proteins and the structures where proteins are made are found in two different locations. DNA is stored in the nucleus, while proteins are assembled from free amino acids in the cytoplasm in structures called ribosomes. A chemical called messenger RNA (mRNA) is made in the nucleus and carries a copy of the DNA base sequence of a specific gene to the cytoplasm. Ribosomes attach to the mRNA and the instructions it carries are used to assemble amino acids in the correct order to make a specific protein. nucleus Inside the cell in the CYTOPLASM, Ribosome produces Proteins 3  Organisms are made up of proteins that are, in turn, made up of amino acids. The amino acids needed for protein synthesis by each organism is encoded in their DNA. Using the processes of transcription and translation, you can, theoretically start with a strand of DNA and calculate the amino acid chains for which an organism is coded. GLOSSARY 1. amino acid The building blocks that make up a protein molecule. 2. bases These are the sub-units of DNA and mRNA which make up the genetic code (A, T, G and C). 3. bond The chemical link that holds molecules together. 4. complementary Refers to the specific way that the bases in DNA pair with each other ( A-T and G-C). 5. double helix The shape of the DNA molecule with two strands twisted together in a spiral. 6. gene The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production. 7. genetic code The code formed by the order of the bases in DNA that determines an organism's characteristics. 8. messenger RNA mRNA is the substance that carries a complementary copy of a gene from the DNA in the nucleus to the ribosomes in the cytoplasm. 9. nucleotide The units or molecules of which DNA is composed. 4