Textbook

• DNA replication is the DNA template directed duplication of the genome prior to cell division.
• Transcription is the DNA template directed biosynthesis of RNA.
• Reverse transcription RNA template biosynthesis of DNA.
• Translation is the mRNA template directed biosynthesis of proteins.
• Transcription is regulated by DNA protein interactions.
• Gene expression is controlled by proteins that recognize particular DNA sequences and bind in those sites. These DNA binding protein can wither activate or repress the expression of certain downstream genes.
• The operon model was made by Jacob and Monod in 1961.
• Bacterial genetics predicted mRNA to be a collection of metabolically active RNAs, present in low abundance, heterogeneous in size, and complementary to sequence region in the DNA genome.
• In the operon model, the first step is the regulator gene R encodes a repressor molecule, which binds to the operator, O, and thereby inhibits transcription of the adjacent structural genes, SG>
• In the operon model, the second step is that a small molecules inducer complexes with the repressor, altering the equilibrium between conformational states of the repressor.
• In the operon model, the third step is the repressor induced complex binds less tightly to the operator.
• In the operon model, the fourth step is the loosening facilities transcription of the structural genes, resulting in the production of mRNA, an RNA copy of structural genes.
• In the operon model, the fifth step is the mRNA sequence is translated into proteins.
• S values refer to the sedimentation coefficients of various particles in Svedberg units. S units depend on size and shape.
• Treatment of bacteria with rifampicin blocks the synthesis of tRNA, rRNA, and mRNA, indicating bacteria contains one RNA polymerase.
• Eukaryotes have three RNA polymerases, identified from their different sensitivities to alpha-amanitin.
• Alpha-amanitin is a toxin from the Amanita mushroom.
• E. coli RNA polymerase is composed of five subunits, alpha, beta, beta', sigma, and omega.
• The alpha subunit of RNA polymerase in E. coli has a Mr of 36,500.
• The beta subunit of RNA polymerase in E. coli has a Mr of 151,000.
• The beta' subunit of RNA polymerase in E. coli has a Mr of 155,000.
• The sigma subunit of RNA polymerase in E. coli has a Mr of 70,000.
• The omega subunit of RNA polymerase in E. coli has a Mr of 11,000.
• The alpha subunit of RNA polymerase in E. coli has 2 subunits.
• The beta subunit of RNA polymerase in E. coli has 1 subunit.
• The beta' subunit of RNA polymerase in E. coli has 1 subunit.
• The sigma subunit of RNA polymerase in E. coli has 1 subunit.
• The omega subunit of RNA polymerase in E. coli has 1 subunit.
• The alpha subunit of RNA polymerase in E. coli functions in chain initiation and interaction with regulatory proteins and upstream promotor elements.
• The beta subunit of RNA polymerase in E. coli functions in chain initiation and elongation.
• The beta' subunit of RNA polymerase in E. coli functions in DNA binding.
• The sigma subunit of RNA polymerase in E. coli functions in promotor recognition.
• The omega subunit of RNA polymerase in E. coli functions in promotion of enzyme assembly.
• The RNA polymerase holoenzyme of E. coli has a molecular weight of about 450,000.
• Although RNA polymerase is active without sigma factor, it binds to many more sites on the DNA than the holoenzyme.
• Sigma factor plays an important role in directing RNA polymerase to the promoter, the site of initiation.
• The consensus sequence indicates the nucleotides most often found at each position.
• Conserved promotor sequences are recognized by E. coli RNA polymerase include the -35 region and the -10 region.
• DNA footprinting analysis identifies RNA polymerase binding sites on DNA.
• The first step of DNA footprinting is DNA binding protein binding to the DNA. Then, DNase I cleaves DNA at random sites, but it can't cut where the DNA binding protein is. Then electrophoresis and radiography has missing spots, which represents where binding sites are.