Protein Synthesis. What are proteins and what are they composed of? What are some of their functions? What determines the final function of a protein?

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1 Protein Synthesis What are proteins and what are they composed of? What are some of their functions? What determines the final function of a protein? What is needed to make specific proteins and what is that process called? Where is this process done? Which enzyme is needed to create the mrn strand? Describe translation.

2 Below is a sequence of mrn that was formed from a DN strand in the nucleus. codon is a three base section of the mrn. Circle the start codon. Fill in the amino acids that will be bound together with peptide bonds and form a protein. What base is present in the RN but not in DN? U G G G C U U G C G U G C U G U U What attaches to the mrn and where does this occur? How many codons does the ribosome cover? When the transfer RN (trn) arrives at the start codon (UG), what amino acid does it bring? Use the code chart below. Where does the trn come from? What are the names of the three unpaired bases on the trn?

3 Using the chart, which amino acid will be brought in next? Which codon did you use to help make your decision? Once two amino acids are brought in, how are the amino acids held together? What happens to the trn that was attached to the first amino acid MET? How and where does the ribosome move? What will the next amino acid be? Use the mrn codon UU. What kind of bond will form between the amino acids?

4 How long will this process continue for? What are the three STOP codons? What happens when that STOP codon is reached? Once the protein is formed, what is its final step? are a permanent change in the. These mutations can alter the of a protein encoded by the gene. Cystic Fibrosis is an disease found on chromosome that affects the and system. The effect is to produce a which clogs the lungs. This will cause a serious. Under normal conditions the CFTR sequence is shown with the amino acid phenylalanine. n individual suffering from CF has a change at the position, missing the Phe. This change has a drastic effect on the protein. It does not function causing mucous to build up in and on the lungs. Scientists can also use amino acid sequences to determine if two species are related.

5 Mutations can be classified as a deletion, an insertion or a substitution. In each case there can be little or no effect or the effect can be so severe that the protein does not function properly. If a mutation causes a STOP codon to be placed too soon, it is said to be a nonsense mutation. Lets look at a couple of examples. DN code T C G G C C C T T T G T T T mrn code mino cid The next three examples have some change. Determine the mutation and if the protein will be affected. Circle each of your choices. DN code T C G G C C C T T T G T T mrn code mino cid Insertion Deletion Substitution Nonsense FFECTED NOT FFECTED DN code T C G G C C C T T C G T T T mrn code mino cid Insertion Deletion Substitution Nonsense FFECTED NOT FFECTED DN code T C G G C C T T T T G T T T mrn code mino cid Insertion Deletion Substitution Nonsense FFECTED NOT FFECTED

6 Name Use the Universal Genetic Code Chart to answer the questions below. ccording to the information, which two species are most closely related. Support your answer. Species and Because

7 Name Protein Synthesis Use the mrn strand to correctly synthesis a protein. Below each codon, write the amino acid (bolded) it codes for and the corresponding letter or word to complete a sentence. Carefully note what happens if the base sequence is altered. These alterations can cause mutations in the protein. BSE SUBSTITUTION: The original base is replaced by one of the other three bases. This may or may not lead to an amino acid substitution/mutation. If there is no affect, it is called a NEUTRL SUBSTITUTION. BSE DELETION: base is missing. This can result in a shift in the reading frame (also known as a frameshift mutation). If the normal protein code is THE FT CT TE THE BIG RT, the protein code resulting from deleting the E in THE would be THF TC T TET HEB IGR T. This mutation could affect the end protein, possibly making it nonfunctional. BSE INSERTION: n extra base has been added. This can result in a shift in the reading frame (frameshift mutation). If the normal protein code is THE FT CT TE THE BIG RT, the protein code resulting from insertion of an extra initial E would be THE EF TC TT ETH EBI GR T. This mutation could affect the end protein, possibly making it nonfunctional. NONSENSE MUTTION: If a codon is changed to a "STOP" codon (U, UG, or UG) translation of mrn would be prematurely terminated. These are called nonsense mutations because the protein is nonfunctional.

8 Below are amino acids in the cytoplasm. HIS TYR PRO LYS I ROUND THIS TODY SN MET RG SER LOVE STRT UP LIKE GLY ILE L LEU CORN MEET CLSS DOWN Below is a functioning mrn. Determine the amino acid sequence which could form a sentence. U G C C U C C G G C C U The next four sequences have been mutated in some way. Determine the amino acid sequence/sentence an record which mutation occurred. Circle the end result of the mutation. U G C C U C C G G C C U U G C C U C C G G C C U G Mutation: Base Substitution Neutral Substitution Insertion Deletion Nonsense Result: None ffected Nonfunctional

9 U G C C U C C G G C C U U G C C G U C C G G C C U Mutation: Base Substitution Neutral Substitution Insertion Deletion Nonsense Result: None ffected Nonfunctional U G C C U C C G G C C U U G C C U C C G G C U Mutation: Base Substitution Neutral Substitution Insertion Deletion Nonsense Result: None ffected Nonfunctional U G C C U C C G G C C U

10 U G C C U C C G G C C U Mutation: Base Substitution Neutral Substitution Insertion Deletion Nonsense Result: None ffected Nonfunctional U G C C U C C G G C C U U G C C U G C C G G C C U U Mutation: Base Substitution Neutral Substitution Insertion Deletion Nonsense Result: None ffected Nonfunctional Which mutation seems to have the most affect on the function of a protein? Explain your answer. Describe what happens if no STOP codon is present. Describe what happens if a STOP codon is in the wrong place (too close to the beginning of the protein).