Protein Synthesis and Mutations

AP Biology-10/20/12
Unit 12 Free Response Question:
The process of making a protein begins in the nucleus and ends in the cytoplasm. a.) Describe the process of protein synthesis in terms of molecular structure of the nucleic acids b.) Explain how a new phenotypic characteristic may result from a change in DNA (mutations)

Proteins are used as a structural material in cells and in enzymes, and they have jobs to do in every part of an organism, even in the organism’s genes. The way in which proteins are created for the purpose of genetic inheritance is in protein synthesis. Protein synthesis follows a very specific order of events and the run-through of how this is all done requires many steps. For this process to occur, certain materials absolutely need to be present. These materials are amino acids, certain enzymes, and two types of nucleic acids called DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). In the synthesis of protein, there are three types of RNA that are utilized. There’s ribosomal RNA (rRNA) which is used to manufacture ribosomes, which are found in the cytoplasm. Ribosomes consist of particles of rRNA and protein, and they are where amino acids link to one another to synthesize proteins. The second type of RNA is transfer RNA (tRNA) which is found in the cytoplasm and which carries amino acids to the ribosomes. During protein synthesis, enzymes link tRNA molecules to amino acids. The third type of RNA is messenger RNA (mRNA) which starts in the nucleus when it receives the genetic code in DNA and moves to the cytoplasm where the actual protein synthesis takes place. One of the first processes that the necessary protein synthesis materials go through is transcription. Transcription results in the synthesis of the mRNA, and starts when RNA polymerase attaches or connects to a section of one of the DNA molecules in the double