1. In most cases, genes code for and it is that

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1 Name Chapter 10 Reading Guide From DNA to Protein: Gene Expression Concept 10.1 Genetics Shows That Genes Code for Proteins 1. In most cases, genes code for and it is that determine. 2. Describe what Garrod meant by inborn errors of metabolism. 3. The idea of one gene-one polypeptide arose from the original idea of one gene-one protein formulated by Garrod. Although useful, why is this an oversimplification? 4. What is molecular biology? 5. Define: a. Transcription b. Translation 6. Briefly explain the roles of the following types of RNA. These will all be explained in more detail in the remaining sections of the chapter. a. Messenger RNA (mrna) b. Ribosomal RNA (rrna) c. Transfer RNA (trna) STOP & WATCH: Bozeman Transcription & Translation 1

2 Concept 10.2 DNA Expression Begins with Its Transcription to RNA 7. What are the 3 requirements for transcription? 8. What is the role of RNA polymerases? How are they similar to DNA polymerases and how are they similar? There are 3 distinct processes involved in transcription. Answer the following questions about each process. 9. INITIATION: a. What is a promoter? b. What two things does the promoter tell the RNA polymerase? c. Where does transcription begin? d. What is the purpose of sigma factors and transcription factors? 10. ELONGATION: a. What unwinds the DNA strand being transcribed? b. What direction does RNA polymerase read the template strand and to what end (of the new RNA strand) are nucleotides added? 2

3 c. What is the major difference from the base pairing that occurs in DNA and RNA? d. Why are transcriptional errors more common but typically less harmful as mutations in DNA. 11. TERMINATION: a. What is the general process of termination in eukaryotes? 12. What is a coding region? 13. Explain the difference between transcription in prokaryotes and eukaryotes. (Be sure to explain the terms introns and exons in your explanation.) 14. What is RNA splicing? 15. Use the figure below to describe the process of RNA splicing. (Be sure to identify snrnps and spliceosome.) 3

4 16. Explain the purpose of the modifications that occur on both ends of the pre-mrna while it is still in the nucleus: a. 5 Cap b. Poly A tail 17. What would be the consequences of the following? a. A mutation of a promoter sequence such that the promoter is deleted. b. A mutation of the gene that encodes RNA polymerase such that the polymerase is not made. c. Deletion of intron consensus sequences from a gene. Concept 10.3 The Genetic Code in RNA Is Translated into the Amino Acid Sequence of Proteins 18. Where does the translation of the nucleotide sequence of an mrna into the amino sequence of a polypeptide occur? 19. Explain the difference between the location of translation in prokaryotes and eukaryotes. 20. Define codons. What are the letter in codons? 21. Define start codon and stop codon. What is the code and amino acid for both? 4

5 22. Explain the concept that the genetic code is redundant but not ambiguous. 23. Explain how the genetic code is a unifying concept for all life. 24. The point mutations discussed in Chapter 9 can now be evaluated based on their effect on polypeptide sequences. Describe each type of mutation below. a. Silent Mutations b. Missense mutations c. Nonsense mutations d. Frame-shift mutations STOP & WATCH: Bozeman Mutations Concept 10.4 Translation of the Genetic Code is Mediated by trna s and Ribosomes 25. What is the function of trna and what does the t stand for? 26. What two key events must take place to ensure that the protein made is the one specified in mrna? 27. There are at least one specific mrna molecule for each of the 20 amino acids. What are the 3 functions of each? 5

6 28. The figure below shows the structure of trna. Label all relevant areas. 29. Explain why there is not 61 different trnas. 30. What enzymes catalyze the charging of a trna? What supplies the energy for this reaction? 31. Explain the basic make up of the large and small subunit of a ribosome. 32. There are three sites on the large ribosomal subunit where trna can attach. Describe what happens at each of these sites: A site P site E site 6

7 33. How are errors avoided when trna is binding to the mrna at these sites? 34. Summarize the events of the 3 stages of translation. 35. What is a polysome? Concept 10.5 Proteins are Modified after Translation 36. Define signal sequence (signal peptide). If there is not signal sequence, where will the polypeptide remain? 37. What are some of the "targets for newly synthesized proteins? 38. Simply define the following types of protein modifications: a. Proteolysis b. Glycosylation c. Phosphorylation 7