Bio 111 Study Guide Chapter 17 From Gene to Protein

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1 Bio 111 Study Guide Chapter 17 From Gene to Protein BEFORE CLASS: Reading: Read the introduction on p. 333, skip the beginning of Concept 17.1 from p. 334 to the bottom of the first column on p. 336, and then read from there on to the end of the chapter. Make sure you study Figure 17.24, as it is a good overview of transcription and translation. Definitions: transcription messenger RNA (mrna) translation ribosome codon genetic code RNA polymerase promoter terminator transcription factors transcription initiation complex TATA box RNA processing RNA splicing introns exons alternative RNA splicing transfer RNA (trna)

2 anticodon ribosomal RNA (rrna) P site A site E site signal peptide polyribosomes mutation point mutation nucleotide-pair substitution silent mutation missense mutation nonsense mutation insertion or deletion frameshift mutation mutagen Questions/Problems: 1. Fill in the following sequence of the flow of genetic information, often called the central dogma. Above each arrow, write the name of the process involved. 2. What is the complementary mrna of a DNA molecule with the bases GTTACGAATGCAGTGAAC?

3 DURING CLASS: Flow of Genetic Information Genetic Code Transcription Purpose Initiation: Elongation: Termination:

4 Post-transcriptional Processing Modifications to mrna: RNA splicing: Alternative RNA splicing: RET Gene Case Study: Remember, the RET gene is found on chromosome 10. It is 55,000 base pairs long, and it contains 21 exons. During post-transcriptional processing, alternate splicing of the RET gene can result in the production of three different isoforms of the protein. They share the first 19 exons which include the main structural domains of the RET protein (see figure above) but differ at their C-terminus. RET51 is followed by an additional 51 amino acids, RET43 is followed by an additional 43 amino acids, and RET9 is followed by 9 additional amino acids The biological roles of isoforms RET51 and RET9 are the most well studied in-vivo, as these are the most common isoforms in which RET occurs. RET9 contains 16 tyrosines which can be phosphorylated, while RET51 contains 18 tyrosines. Through several scientific studies, they have been shown to have distinctly different functions as receptors, even within the same cell.

5 Translation Purpose Initiation: Elongation: Termination: Post-translational Processing Bioflix Animation Protein Synthesis

6 Mutations **Take Away Concept** Transcription and translation are the key processes that use the information in genes to make proteins, without which our cells couldn t function.

7 AFTER CLASS: Questions/Problems: 1. Which of the following is not true of a codon? a. It consists of three nucleotides. b. It may code for the same amino acid as another codon. c. It extends from one end of a trna molecule. d. It is the basic unit of the genetic code. e. It is found on an mrna transcript. 2. Fill in the following table below to summarize transcription and translation. Transcription Translation Template molecule Location Molecules Involved Control (start & stop) Product Processing Involved 3. How does the mrna that leaves the nucleus differ from the initial mrna that was made? 4. Explain how mutations are the main source of genetic change that leads to evolution.

8 5. Without referring to your textbook, label the following in the figure below: nucleus, cytoplasm, ribosome, transcription, translation, DNA, promoter, TATA box, transcription factors, RNA polymerase, terminator, intron, exon, RNA transcript, poly-a tail, 5 cap, amino acid, trna, codon, anticodon, P site, A site, E site, peptide bonds, and polypeptide. Note you may have to draw a few in. RET Gene Case Study: Currently, there are more than 250 disease causing mutations known in the RET gene. The disease and its level of severity are determined by the site of amino acid substitution. For our class, we are concerned with mutation V804L. The cause of this mutation is that a C (cytosine) nucleotide was inserted where a G (guanine) nucleotide should have been at nucleotide position The corresponding amino acid position is 804, where the mrna codon should have been GUG, but instead is CUG. Using Figure 17.5 which shows the genetic code, what amino acid does the codon GUG code for? What amino acid does the codon CUG code for? Where does the name V804L for the mutation come from? What kind of mutation is this (silent, missense, nonsense, or frameshift)?