Current LectureMCB 250 1st Edition Lecture 15Outline of Current Lecture 1. Rho-Dependent Termination2. Anti Termination3. Transcription of E. Coli4. RNASEP5. Translation6. tRNACurrent Lecture1. Rho-Dependent Termination- Role of Rho is to sense when the ribosomes are done translating the message and are nolonger chasing the RNA polymerase down the DNA, Rho will load and terminate transcription- Not ALL RNA is translated. Only mRNA are translated. tRNA and rRNA are never translated (the ribosomes never interact/chase them)- How do we deal with Rho terminate transcription: Anti termination2. Anti Termination- Auxiliary proteins that interact with RNA polymerase and cause it to be refractory to Rho- No longer respond to Rho-dependent termination 3. Transcription of E. Coli- How many +1 are there in the chromosomes of E. Coli: thousands. Thousands of start sites of transcription for the 4500 genes. Not all on the same strand of DNA. Genes are found on both strand of the DNA. - Making rRNA with a big transcript (thousands of nucleotides)- Anti-terminative: nothing is being translated; RNA itself is the structural unit. Need to process the functional RNA’s out of this transcript- There are specific ribonucleases that recognize structures more than sequence and cleave the process of the RNA’s to release the functional units.- 16s is in the transcript and the RNA is folding up into the 3D structure while it is still transcriptingThese 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.- Folds into a complex 3D structure- While its folding, the end of it is being recognized by nucleases of stem loops that cleans it up4. RNaseP- TRNA’s also have to be processed. - RNaseP is found in all 3 domains of life (eukaryotes, bacteria, archae)- RNase P is a ribozyme5. Translation- mRNA is read in triplet codons, - Ribosome function is to synthesize the protein corresponding to the codons in the message- tRNA translator between two- Protein synthesized based on codon and is attached to the tRNA. That tRNA is in the P site.- New tRNA “charged” tRNA with the appropriate amino acid will come into the A site. The free amino group will attack the high energy bond and peptide will move from P to A. 6. tRNA- Adaptor between the mRNA codons and the amino acids- All tRNA has the CCA invariant- Appropriate amino acid attaches to the A at the 3’ end. - There is a bond that connects that. You need energy to make that bond. The enzyme that does this is aminoacyl-TRNA synthetases. It will “charge” the tRNAwith amino acid. It does so in a 2 step reaction uses ATP as an energy source- 1. Enzyme will take the appropriate amino acid and attach AMP to it.- Carboxyllic acid on the amino acid will attack the phosphate, throw out the pyrophosphate. Have AMP attached to the carboxylic acid. (high energy bond)- Then take high energy bond and use it with the 3’OH group to attack the bond and create a linkage between the amino acid and the tRNA.- The bond still has high energy. That’s the bond that the amino group will form the peptide bond. - Activate amino acid with AMP and use energy from that to create the linkage to the tRNA then it will be used for the peptide
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