BIMM100 Final Exam

Fill in ALL of the blanks with the best word(s) for the following statements. A. The polymerase __________________ synthesizes mRNAs, the polymerase __________________ synthesizes pre-rRNAs and the polymerase __________________ synthesizes tRNAs and 5S rRNAs. The polymerase __________________ adds adenosines to the 3' ends of most mRNAs and some viruses utilize a polymerase called __________________ to copy their RNA genomes into DNA. B. During pre-mRNA splicing, __________________ base pairs to the 5' splice site and __________________ base pairs to the branch point A, which is located in the __________________ of the pre-mRNA. During this process the __________________ are removed and the __________________ are ligated together to form the mature mRNA. C. Initiation of translation in Eukaryotes, starts with binding of the __________________ of the mRNA by the pre-initiation complex. The complex scans the mRNA for the __________________ which is recognized by base-pairing to the __________________ of the initiator tRNA. Once the __________________ subunit joins, the complete initiation complex begins the elongation phase, which enables the formation of __________________ bonds between amino acids brought in by the appropriate tRNAs base-pairing to the __________________ sequences in the mRNA. Synthesis ends when __________________ recognize the STOP codon. __________________ formation allows more than one ribosome to translate a mRNA at a time, which increases the efficiency of protein production. D. __________________ are mobile DNA elements and those that move by the copy and paste mechanism are of the __________________ type, while those that use the cut and paste mechanism are of the type __________________. E. DNA replication is regulated by binding of __________________ proteins to the __________________ in DNA. First, a primer composed of __________________ is synthesized so that __________________ can then continue synthesis with deoxynucleotide triphosphates. LAST NAME: ______________________ FIRST NAME: ______________________ 3 2. Answer the following (16 points) (point values for each question are indicated) A. MYC encodes a protein that is mis-regulated in many types of cancers. Studying this gene in mouse models, scientists have discovered that loss of MYC results in death during embryogenesis but overexpression of MYC promotes cancer. One of the reasons why mice lacking MYC die during embryogenesis is that angiogenesis (blood vessel formation) fails. Explain how this phenotype relates to cancer development caused by overexpression of MYC. (2). ______________________________________________________________________________ B. Based on the above information, is MYC a proto-oncogene or a tumor suppressor gene? (1) ______________________________________________________________________________ C. Explain your answer to (B). (2) ______________________________________________________________________________ To analyze MYC expression in several types of tumors, you perform Northern Blotting, shown below. Answer the following: D. Based on the Northern results, mis-regulation of MYC may contribute to which tumor type(s). (1) ______________________________________________ E. Briefly explain your answer to B. (2) ______________________________________________________________________________ F. By performing Western blotting, you discover that MYC protein levels are increased in all 3 tumor types. For each tumor type, describe one type of mutation in the MYC gene that could result in high MYC protein levels and is consistent with the Northern data. (6) Brain – Lung – Liver – ______________________________________________________________________________ G. Explain why 18S rRNA was also probed on the Northern Blot. (2)