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9 Cards in this Set
- Front
- Back
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Describe the structural features of a gene and their functions
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<img src="pastezzpjrx.jpg" />
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Describe the types and functions of the four different cellular RNAs
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<img src="pastezfx7eh.jpg" />
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Describe the major steps of RNA synthesis in prokaryotes and eukaryotes
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<img src="pastehvel_8.jpg" />
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Explain the function and structure of DNA sequences that are involved in the initiation and termination of transcription
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Promoters
Prokaryotes & eukaryotes have different promoter consensus sequences. Prokaryotic promoter sequences are generally found at -35 & -10 bp from the transcription start site (-35 consensus sequence = 5’-TTGACA-3’; -10 consensus sequence [Pribnow box] = 5’-TATAAT-3’ ) Eukaryotic promoters typically consist of a group of short conserved sequences. Some of these are theTATA box (5’-TATAAA-3’), GC box (5’-GGGCGG-3’) & the CAAT box (5’-CCAAT-3’). Terminators Prokaryotes = Rho-dependent & independent mechanisms. Eukaryotes = Pol I uses a polymerase-specific termination factor on DNA. Pol III -Terminates after polymerizing series of U residues. Pol II mechanism is linked to cleavage & polyadenylation of the RNA |
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List the RNAs that are transcribed by the different RNA polymerases in eukaryotes
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3 different polymerases I, II & III which each transcribesdifferent types of RNA.
1) RNA pol I: 5.8S, 18S & 28S rRNAgenes (nucleoli). 2) RNA pol II: all protein-coding genes (mRNA) &some snRNAs. 3) RNA pol III: tRNAgenes & some snRNAs |
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Rifampin
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Action: Transcription inhibitor
Mechanism: Binds to the RNA polymerase and changes its conformation so that it can't initiate RNA synthesis Use: Particularly active against gram positive bacteria and tuberculosis Brand Name: Rifamyacin |
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Actinomycin D
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Action: Stops splicing in eukaryotes and prokaryotes
Mechanism: inhibits formation of ssDNA |
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Alpha - Amanatin
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Action: Inhibits transcription in eukaryotes (poison)
Mechanism: Forms tight complex with RNA Poly II, inhibited the conformational change required for translocation along the temple Use: Renal and Hepatic failure, death in 7-10 days |
