BOLOGY 107 Lecture 28Outline of Last Lecture I. DNA Replicationa. Polymerasesb. Proofreading c. Eukaryote problemII. Gene Expressiona. “Central Dogma”b. Transcription Outline of Current Lecture III. Gene Expressiona. Transcription (cont.)b. RNA Processingc. TranslationCurrent LectureGene Expression1) Transcription (cont.)a) Uses ribonucleotides, replace thymine with uracilb) DNA strands separate into the template strand and the coding strandc) Initiationi) Transcriptions factors bind to DNA at specific sequence where RNA synthesis is to begin(1) Sequence is referred to at the promoterii) Bound factors load on RNA Polymerase II(1) Seperates DNA and starts synthesisd) Elongation i) Similar process as DNA Pol III, just using ribonucleotide triphosphate(1) Instead of thymine, adenine is paired with uracilii) RNA is separated, DNA re-associatesiii) Topoisomerase is still usede) Termination i) Disruption is transcription complex(1) Bacteria have two ways to disrupt(2) Eukaryotes have one way to disruptThese 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.2) RNA processinga) Mostly in eukaryotes i) Product of transcription is pre-mRNA(1) Needs modified before it leaves the nucleusii) Occurs contemporaneous with transcriptioniii) Modifications:(1) 5’ cap added- an extra methylated guanine is added to the 5’ end(2) 3’ poly-andenylation- a large amount of adenines are added to the 3’ end(3) Intron splicing- sections of the middle are removed, leave exons(a) Done by splicosome(i) Uses sequence-specific base pairing to recognize the sequences tobe removed(b) Done to create variability(i) More than one protein can be created off of one gene(c) Acts as a form of error recognition(d) Evolution- recombine protein domains(i) Domains in proteins distinguish functions1. Exons code domains2. Allows for molecular protein constructiona. Remove or leave domains trough splicingb. Cross-over errors bring new domains together to form newproteinsiv) mRNA structure after:(1) 5’ cap, 5’ UTR (un-translated region), start codon, code sequence, stop codon, 3’ UTR, poly-A tail3) Translationa) Genetic code mRNA is read in sets of three to form codons i) Codons code for amino acid, some codons code for the same acid(1) Start- AUG(2) Stop- UAA, UAG, or UGAb) Carried out by ribosomei) mRNA- read by ribosomeii) tRNA (transfer)- to bridge mRNA to amino acid, made of anti-codonsiii) rRNA (ribosomal)- performs enzymatic function within
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