Review for Chapter 7 (Lecture 5 and 6) 1. The instructions specified by the DNA will ultimately specify the sequence of proteins. This process involves DNA, made up of ____ different nucleotides, which gets _________________ into RNA, which is then _________________ into proteins, made up of _____ different amino acids. In eukaryotic cells, DNA gets made into RNA in the _________________, while proteins are produced from RNA in the _________________. The segment of DNA called a _________________ is the portion that is copied into RNA; this process is catalyzed by RNA _________________. 4 gene proteasome exported nucleus 20 Golgi replisome polymerase transferase 109 kinase sugar-phosphate translated 128 nuclear pore transcribed cytoplasm 2. Use the numbers in the choices below to indicate where in the schematic diagram of a eukaryotic cell those processes take place. 3. Which of the following are required for the DNA-dependent RNA polymerase reaction to produce a unique RNA transcript? a) ATP b) CTP c) GTP d) dTTP e) UTP f) DNA g) RNA h) Promoter sequence i) operator sequence j) terminator sequence 4. Unlike DNA, which typically forms a helical structure, different molecules of RNA can fold into a variety of three-dimensional shapes. This is largely because ___________________. (a) RNA contains uracil and uses ribose as the sugar. (b) RNA bases cannot form hydrogen bonds with each other. (c) RNA nucleotides use a different chemical linkage between nucleotides compared to DNA. (d) RNA is single-stranded. 1. transcription 2. translation 3. RNA splicing 4. polyadenylation 5. RNA capping5. For a cell’s genetic material to be used, the information is first copied from the DNA into the nucleotide sequence of RNA in a process called __________________. Various kinds of RNA are produced, each with different functions. __________________ molecules code for proteins, __________________ molecules act as adaptors for protein synthesis, __________________ molecules are integral components of the ribosome, _____________ molecules regulate gene expression, and __________________ molecules are important in the splicing of RNA transcripts, gene regulation, telomere maintenance, and many other processes. 6. Imagine that an RNA polymerase is transcribing a segment of DNA that contains the following sequence: 5′-AGTCTAGGCACTGA-3′ 3′-TCAGATCCGTGACT-5′ A. If the polymerase is transcribing from this segment of DNA from left to right, which strand (top or bottom) is the template? B. What will be the sequence of that RNA (be sure to label the 5′ and 3′ ends of your RNA molecule)? 7. List three ways in which the process of eukaryotic transcription differs from the process of bacterial transcription. 8. Name three covalent modifications that can be made to an RNA molecule in eukaryotic cells before the RNA molecule becomes a mature mRNA. 9. Match the following types of RNA with the main polymerase that transcribes them. 8. In eukaryotic cells, general transcription factors are required for the activity of all promoters transcribed by RNA polymerase II. The assembly of the general transcription factors begins with the binding of the factor __________________ to DNA, causing a marked local distortion in the DNA. This factor binds at the DNA sequence called the __________________ box, which is typically located 25 nucleotides upstream from the transcription start site. Once RNA polymerase II has been brought to the promoter DNA, it must be released to begin making transcripts. This release process is facilitated by the addition of phosphate groups to the tail of RNA polymerase by the factor9. The length of a particular gene in human DNA, measured from the start site for transcription to the end of the protein-coding region, is 10,000 nucleotides, whereas the length of the mRNA produced from this gene is 4000 nucleotides. What is the most likely reason for this difference? 10. The genetic code specifies which amino acids are encoded by the codons on the mRNA. It is ________________ because some amino acids have more than one codon. ____________ codons do not specify an amino acid. 11. Use the genetic code shown to identify which of the following nucleotide sequences would code for the polypeptide sequence arginine-glycine-aspartate: a. 5’-AGA-GGA-GAU-3’ b. 5’-ACA-CCC-ACU-3’ c. 5’-GGG-AAA-UUU-3’ d. 5’-CGG-GGU-GAC-3’ 12. Which of the following is not a key advantage of wobble in the codon-anticodon reaction? a. It allows for fewer tRNAs in the cell. b. It allows for making more than one protein from the same coding sequence. c. It allows for a certain amount of mutation in the mRNA without affecting the protein sequence. d. All of these are advantages of wobble. 13. The _______________ in a tRNA molecule is designed to base-pair with a complementary sequence of three nucleotides, the ________________, in an mRNA molecule. 14. Wobble base-pairing occurs between the first position in the codon and the third position in the anticodon. (True or false) 15. In all cells, a special_____________ molecule, recognizing the ___________________codon AUG and carrying the amino acid _________________, provides the amino acid that begins a protein chain. 16. Which of the following pairs of codons might you expect to be read by the same tRNA as a result of wobble? (a) CUU and UUU (b) GAU and GAA (c) CAC and CAU (d) AAU and AGU17. The piece of RNA below includes the region that codes for the binding site for the initiator tRNA needed in translation. 5′-GUUUCCCGUAUACAUGCGUGCCGGGGGC-3′ Which amino acid will be on the tRNA that is the first to bind to the A site of the ribosome? (a) methionine (b) arginine (c) cysteine (d) valine 18. A mutation in the tRNA for the amino acid lysine results in the anticodon sequence 5′-UAU-3′ (instead of 5′-UUU-3′). Which of the following aberrations in protein synthesis might this tRNA cause? (a) read-through of stop codons (b) substitution of lysine for isoleucine (c) substitution of lysine for tyrosine (d) substitution of lysine for phenylalanine 19. Once an mRNA is produced, its message can be decoded on ribosomes. The ribosome is composed of two subunits: