MICRO-s10_14 - 3/15/2010 BIOL 240: General Microbiology...

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Unformatted text preview: 3/15/2010 BIOL 240: General Microbiology Spring 2010 Rm. 22-116 T, Mar. 16, 2010 22http://www.smccd.edu/accounts/staplesn/biol240/ 1. Pre-Lab Writeups: Be sure to prepare before each Monday’s labs (for Lab Writeups Be sure to prepare before each Monday labs (for BOTH BOTH Mon. & Wed.)!! (What? Why? How? are we doing in the lab??) Wed.)!! 2. Be sure to keep up with BY ARRANGEMENT HOURS!! They are REQUIRED for your grade!! -- average TWO documented hours/week. -- 3. MT1 M/C Answer KEY is posted. Check and report any corrections by TODAY! • under Add under “Add’l Materials” tab. tab 4. NEXT week: water sample from OUTDOOR source!! 5. QUIZ #4 Due Thursday!! Due 6. Notebook Checks “THIS week”, 3/16: Expt. 1-10, etc.!!! “THIS 1- etc.!!! 1. 1. Ch. 6: Describe several physical and chemical requirements for microbial growth, and physical explain what factors determine optimal conditions. 2. Define the terms that describe organisms that prefer high, medium, or low levels of each high, physical factor affecting growth. 3. Diagram and define the four phases of a bacterial growth curve. phases 4. Compare several methods of measuring microbial growth. measuring REVIEW: TODAY’s Objectives: Students should be able to... Students 1. Ch. 8: Describe the Central Dogma of molecular genetics and the three Central processes that drive the flow of genetic information in an organism. 2. Describe several properties of DNA and the process of DNA replication that contribute to properties DNA DNA’s DNA’s central role as the hereditary material. 3. Draw a replication fork and label 5 enzymes involved in DNA replication. Describe the enzymes function of each enzyme. 4. Compare and contrast DNA Synthesis (Replication) with RNA Synthesis (Transcription). Why is it suitable that RNA is a less stable molecule than DNA? (THINK: Structure Function!!! ….. ALWAYS!!) [Make a table!] (THINK: Function [Make 1 3/15/2010 Chapter 8 Microbial Genetics Terminology 1. Genetics: Study of what genes are, how they carry information, how information is expressed, and how genes are replicated; “the science of heredity” li “th 2. Gene: Segment of DNA that encodes a functional product, usually a protein 3. Genome = All of the genetic material in a cell 4. Genomics = Molecular study of genomes Molecular study of genomes 5. Genotype = Specific forms of genes in an organism – Types of alleles present. 6. Phenotype = physical characteristics resulting from physical expression of the genes 2 3/15/2010 E. coli The Model Organism for molecular biology. Figure 8.1a Flow of Genetic Information: The Central Dogma DNA (m)RNA (m)RNA Protein Protein Figure 8.2 ** Central Dogma of Molecular Genetics ** Central 3 3/15/2010 8.1) DNA DNA Figure 8.3 1. Polymer of nucleotides: adenine, thymine, cytosine, guanine (ATGC) 2. Double helix associated with proteins 3. "Backbone" is deoxyribosedeoxyribose-phosphate 4. Strands held together by Strands held together by hydrogen hydrogen bonds between A=T A=T and G≡C 5. Strands are Antiparallel Antiparallel • 5’ (PO4) 3’ (OH) polarity DNA • Semi-Conservative SemiReplication Replication: – Each “parental strand” “parental serves as template… template… – for synthesis of a new “daughter strand” – Following complementary complementary basebase-pairing rules • A=T • G≡C – Rules allow one to predict 2nd strand sequence from 1st!!! Figure 8.3 http://ncc.gmu.edu/dna/repanim.htm 4 3/15/2010 DNA Replication • 5’ 3’ 3’ synthesis • Template read 3’ 5’ 5’ Figure 8.5 DNA Replication 1. Open helix at Origin, lay-down primers: laya) DNA Helicase “melts” strands apart, breaking H-bonds “melts” Hkeep b) Single-Strand Binding Proteins (SSB) keep template strands apart. Singlec) RNA Primase llays down first several nucleotides (RNA!!) – gives “starting block” ays (free (free 3’-OH) to begin actual DNA synthesis. [Primers are removed later!] [Primers 2. DNA = copied by DNA polymerase III (Dpol3) DNA 3. In the 5′ → 3′ direction – new nucleotides added to the 3’ hydroxyl (-OH) group on deoxyribose in the growing strand (– • • Initiated by an RNA primer (RNA Primase enz.) RNA follows fork (1/fork; 2/ “bubble”) fork (1/fork; 2/ bubble Opposite to fork movement Okazaki Okazaki fragments (unsealed lagging pieces) 4. Leading strand synthesized continuously 5. Lagging strand synthesized discontinuously 6. RNA primers are removed and Okazaki fragments joined by DNA “fill “fill and seal” to finish job!! DNA DNA polymerase I & DNA ligase http://bioteach.ubc.ca/TeachingResources/MolecularBiology/DNAReplication.swf http://www.wiley.com/college/pratt/0471393878/student/animations/dna_replication/index.html 5 3/15/2010 DNA Replication Fork Figure 8.6 III Leading Helicase Primase http://nobelprize.org/educati onal_games/medicine/dna/a/ replication/lagging_ani.html I Lagging http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dnahttp://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf http://www.johnkyrk.com/DNAreplication.html http://www.wehi.edu.au/education/wehihttp://www.wehi.edu.au/education/wehi-tv/dna/replication.html DNA replication is Semiconservative Bidirectional Semiconservative & Bidirectional • Replication results in two daughter DNA duplexes, •each with one each with one completely completely new strand, & •one old strand (parental strand) • = “SEMI-CONSERVATIVE” “SEMI- Figure 8.6 http://www.wehi.edu.au/education/wehihttp://www.wehi.edu.au/education/wehi-tv/dna/replication.html • Two replication forks move in opposite directions = •“Replication Bubble” 6 3/15/2010 8.2) Transcription: RNA Synthesis RNA 1. DNA is transcribed to make RNA (AUGC) a) mRNA = messenger RNA translated translated to protein b) tRNA = transfer RNA brings brings amino acid to ribos. c) rRNA = ribosomal RNA ribosomal RNA makes up ribo; catalytic makes up ribo; catalytic 2. Transcription begins when RNA polymerase RNA binds to the PROMOTER sequence PROMOTER 3. Transcription proceeds in the 5′ 3′ direction (same in ALL nucleic acid synthesis!) • new nucleotides added to the 3’ hydroxyl group on ne added to the 3’ gro on ribose ribose in the growing strand 4. Transcription stops when it reaches the Terminator Sequence (often many U’s or “hairpin loop”) • New RNA and Rpol fall off of DNA template. http://www.stolaf.edu/people/giannini/flash animat/molgenetics/transcription.swf http://vcell.ndsu.nodak.edu/animations/ transcription/movie.htm Figure 8.7 7 3/15/2010 RNA processing in Eukaryotes “Primary transcript” (coding exons + noncoding introns) Primary transcript (coding exons noncoding introns “Mature messenger RNA” (introns removed) (introns Exits nucleus to be translated by ribosomes Ribozymes!!! Ribozymes!!! Nuclear pores Figure 8.11 8.3) Translation 1. mRNA is translated in Codons Codons – 3 nucleotide “words” nucleotide words 2. Translation of mRNA begins at the start start codon: AUG 3. Translation ends at a STOP (“ STOP (“nonsense”) codon codon: UAA, UAG, UGA – Do NOT encode an amino acid!!! Figure 8.2 8 3/15/2010 The “Universal” Genetic Code Figure 8.8 • tRNA (transfer RNA) = adapter molecule that reads “3 letter” codons – via it’s complementary “Anticodon”! • Puts in the right amino acid in right order • Reads mRNA 5’ 3’, 3’ • synthesizes N C polypeptide • Amino Carboxy Carboxy! • Anticodon-Codon base Anticodonpairing http://www.lewport.wnyric.org/jwanamaker/ animations/Protein%20Synthesis.html A. Translation – Initiation Large 3’ 1. 5’ Small Figure 8.09.1 http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf http://highered.mcgrawhttp://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html# 9 3/15/2010 B. Translation - Elongation 2. Peptidyl-site eptidylAmino Acyl-site Acyl- 3’ 5’ Exit-site xit- E P A Figure 8.09.2 Peptidyl Transferase 3. C N 3’ 5’ Translocation Figure 8.09.3 10 3/15/2010 Newly elongated peptide in A site, then then 4. Peptide bond!! C —N PP now in P site! 5’ 3 NT NT Translocation 3’ Figure 8.09.4 5. Ribosome Translocates 3nt in the 3’ direction 3’ 5’ Translocation Translocation 3 NT Figure 8.09.5 11 3/15/2010 Translation: Peptidyl Transfers & translocations continue 6. 3’ 5’ 3 NT….. Figure 8.09.6 Translocation C. Translation - Termination 7. Figure 8.09.7 5’ RF Last AA inserted BEFORE stop codon!! 3’ • No tRNA, but a protein protein “Release Factor Factor” enters empty A site at a stop codon 12 ...
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This note was uploaded on 03/18/2010 for the course BIOL 240 taught by Professor Staples during the Spring '09 term at Canada College.

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