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What are chromosomes composed of? They are made of DNA which is composed of thousands of genes. What forms the rungs of the DNA ladder? Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). (nitrogen bases) Why is the sequence of bases important? They are in a specific order. Protein synthesis The production of proteins. Where does protein synthesis take place? The ribosomes in the cytoplasm of the cell. Where are chromosomes located? Inside the nucleus. How does the information needed to produce proteins get from the nucleus to the ribosomes out of the cytoplasm? Before protein synthesis, a messenger carries the genetic code from the DNA in the nucleus into the cytoplasm. The messenger is called RNA. Three differences of RNA from DNA? 1. RNA has one strand and DNA has two. 2. RNA and DNA contain different sugar molecules. 3. RNA contains uracil and DNA contains thymine. Messenger RNA (mRNA) RNA that copies the coded message from DNA in the nucleus and carries the message into the cytoplasm. Transfer RNA (tRNA) RNA in the cytoplasm that carries an amino acid to the ribosome and adds it to the growing protein chain. What do genes code for? To tell the cell what protein to produce. What happens during protein synthesis? The cell uses information from a gene on a chromosome to produce a specific protein. What is the role of messenger RNA? To copy the coded message from DNA in the nucleus and carry the message into the cytoplasm. What is the role of transfer RNA? To carry and amino avid to the ribosome and add it to the growing protein chain. What is the first step in protein synthesis? The DNA molecule "unzips" between base pairs, RNA bases match up with one of the DNA strands and transfer the genetic information Why is this important? It is important because the genetic information in the DNA is needed in the messenger RNA strand. What does mRNA do in Step 2? It enters the cytoplasm, attaches to a ribosome, where the production of the protein chain begins, and the ribosome moves along the mRNA strand. How is the protein chain formed in step 3? When amino acids link and the order of amino acids is determined by the 3-letter codes on the messenger RNA. Why is it important that protein synthesis be so carefully organized and carried out? It is important because if one mistake is made it can cause change in a gene or chromosome. In what ways can a mistake be made in this process? Instead of the base A, the DNA molecule might have the base G and would cause change in a gene or chromosome. What are these mistakes called? Mutations How can mutations affect an organism? It can cause a cell to produce an incorrect protein and could change an organism's trait.