ZOL 341 Lecture 5 Outline of Last Lecture I Proofreading II Telomeres III PCR IV Sanger sequencing Outline of Current Lecture II Replication III RNA IV Process of bacterial transcription V Transcription termination Current Lecture context of replication purpose is to accurately copy chromosomes in preparation for cell division happens in the nucleus happens during interphase will cover in later lecture RNA structure is similar to DNA but has uracil instead of thymine and ribose instead of deoxyribose has OH on 2 carbon instead of H is located in the cytoplasm and the nucleus mRNA produced by protein encoding genes is a short lived intermediary between DNA and protein and is the only type of RNA that undergoes translation transfer RNA tRNA bind an amino acid and deliver it to the ribosome ribosomal RNA rRNA combines with numerous proteins to form ribosomes small nuclear RNA snRNA found in the nucleus of eukaryotes and plays a role in the processing of mRNA These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute micro RNA miRNA involved in posttranscriptional regulation of mRNA in plant and animal cells small interfering RNA siRNA protects plant and animal cells from production of viruses and movement of transposons bacterial transcription start of transcription is labeled as 1 nucleotide promoter sequence controls the access of RNA polymerase to the gene upstream closer to 5 of coding nontemplate strand coding region portion of the gene that contains the information needed to synthesize the protein product termination region regulates stopping of transcription downstream closer to 3 of coding nontemplate strand steps of transcription 1 promoter recognition consensus sequences recognized at 10 position is Pribnow box TATAAT at 35 position is TTGACA RNA polymerase binds to 10 and 35 sequences and occupies the space between and around them 2 transcription initiation a RNA polymerase core enzyme and sigma subunit bind to 10 and 35 promoter consensus sequences b DNA unwinds near the start of transcription to form the open promoter complex 3 chain elongation a RNA polymerase holoenzyme initiates transcription and begins to synthesize RNA b the core enzyme synthesizes until it encounters the termination sequence 4 chain termination core enzyme and RNA transcript are released transcription termination intrinsic termination dependent only on the presence of the termination sequence inverted repeat sequence of nucleotides followed downstream by its reverse complement form a shot stem loop structure called a hairpin rho dependent termination requires a different termination sequence and presence of the rho protein
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