Chapter 9 - Part 1 (Biology) PDF

Information in Biology Replicati Genoty DN on A pe Transcripti on RN Environm Translati A ent...

Information in Biology Replicati Genoty DN on A pe Transcripti on RN Environm Translati A ent on Prot ein Phenot Review Structures of these Biologically Important Polymers DN A RN A Prot ein Central Dogma – Unique features in bacteria Replicati on DN A Transcripti on RN Translati A on Prot Each ein process: 1.Initiation 2.Elongatio  Review DNA How do we discover DNA was the molecule of inheritance?  Department of Commerce Bureau of the Census “CDC’s Mortality Cause of Statistics Death Report 1920” Pneumococcal Sputum smear that has been pneumonia Gram stained Emoji Experiment 194 4 195 3 The Structure of DNA: Double Helix 2 Access the text alternative for slide ima ges. Review Structure of DNA Central Dogma – Unique features in bacteria Replicati on DN A Transcripti on RN Translati A on Prot Each ein process: 1.Initiation 2.Elongatio Replication is a Semi-Conservative Process  Terminat ion Initiati Elongat on ion  Figure 9.8 Major steps and enzymes involved in 4. Before synthesis of the lagging can start, a primase adds an strand elongation 5. DNA polymerase I the RNA primers and fills in removes RNA primer to direct the DNA the correct complementary DNA nucleotides at the 6. Unjoined ends of polymerase nucleotides (a nick) open the III. Synthesis produces unlinked must 3. The template for the segments of lagging RNA primer and sites. 5 ‘to runs 3’ (opposite to the leading be connected by a strand new ligase. strand), 5 DNA called Okazaki fragments. so to make the new strand in the 3 ’3 5’ to 3’ ’ ’ orientation, synthesis must Nic proceed LAGGING STRAND SYNTHESIS k 3 backward, away from the ’ replication 5 5 ’ fork. ’ 2. The template for the leading strand (blue) is oriented 3’ to 5’. This allows the DNA polymerase III to add nucleotides in 1. The chromosome to the 5’ to 3’ direction toward the replication fork, so it can be bereplicated is unwound by a helicase, forming a synthesized as a continuous strand. Note that direction of replication fork with two synthesis refers to the order of the new strand (red). template strands. LEADING STRAND SYNTHESIS 3 5 5 Origin of a ’ ’ ’3 replication ’ Template Primas Replication strand New eDNA polymerase forks strand III RNA DNA primer polymerase I Helicas Ligas e e  Terminati on Initiati Elongati on on Transcripti 1.Initiation on 2.Elongatio n 3.Terminati on Transcription – Unique features in bacteria Where do these processes take place? Eukaryot Bacter es DN ia A Transcripti on RN Translati A on Prot ein Central Dogma – Unique features in Protein coding bacteria cont. genes Unique organization of Bacterial genes Unique organization of Bacterial Bacter ia genes DN A Transcripti on Cytopla RN sm Translati A on Prot ein No time for post-transcriptional  Transcripti 1.Initiation on 2.Elongatio n 3.Terminati on Transcription Initiation Transcription Initiation RNA P  Figure 9.13 1 Each gene contains a RNA polymerase binding specific promoter region site Leader Initiation Termination and a leader sequence for sequence codon sequences guiding the beginning of Promoter transcription. Next is the region ( ) region of the gene that T A C G A C T G A T G C G A C T G A T G codes for a polypeptide A T G C T G A C T A C G C T G A C T A C and ends with a series of ( ) terminal sequences that RNA Intervening sequence of variable stop translation. polymerase size Termination Template 2 DNA is unwound at strand 5 sequence Sigma 3 the promoter by factor ’ ’ Transcripti RNA polymerase. Only one strand of DNA, 5 3 called ’ Nontemplate on ’ Unwinding of the template strand, strand DNA supplies the codes to Direction 3 The RNA polymerase be transcribed by transcripti of Elongation moves along the DNA RNA polymerase. on strand, adding This strand runs in complementary the 3’ to 5’ nucleotides direction. as 3 dictated by the DNA ’ template. The mRNA Nucleotide strand reads in the 5’ 5 pool to 3’ direction. ’Early mRNA transcript Elongatio 4 The polymerase n continues transcribing until it reaches a 3 termination site, and the ’ mRNA transcript is released to be translated. Note that 5 Late mRNA the section of the transc-’ transcript  Transcripti on Terminatio n Other mechanisms but outcome is Central Dogma – Unique features in bacteria Replicati on DN A Transcripti on RN Translati A on Prot Each ein process: 1.Initiation 2.Elongatio  Translati on Nucleic acid language to amino acid language Genetic code -Unique to Bacteria? Nearly  Figure 9.16 DNA Nontemplat triplets e AT CT G strand G TA GA C C Template mRNA AU CU strand codons G G tRNA anticodo ns Protein (amino acids ine Leuc nine Threo nine Threo nine fMethio specified) Same amino acid; has a dierent codon and anticodon Transfer RNA  Location of Translation Ribosome = rRNA and proteins Ribosome is a ribozyme 30S + 50S = 70S Assemble during  Figure 9.15 Second Base U C Position A G UUU UCU UA UGU U Phenylalani Tyrosin Cystein UUC UCC UAC UGC C U ne e e Serin UU UCA UA UGA STOP* A Leucin e STOP* AUG U UCG A UAG UGG * Tryptopha G e * CUU CCU CAU CGU n U Histidin CUC CCC CAC CGC C C Leucin Prolin e Arginin CUA CCA e CA CGA e A e Third Base First Base Glutamin CUG CCG A CAG CGG G Position e AU ACU AA AGU Serin U Isoleucin Asparagin U AUC e ACC UAC A AGC e C A Threonin e AU ACA AA AGA A e Lysin Arginin A AUG START Methionin ACG A AA AGG G f e e * e G GUU GCU GAU GGU U Aspartic GUC GCC GAC GGC C G Valin Alanin acid Glycin GUA e GCA e GA GGA A AAG Glutamic e GUG GCG G GGG G acid * This codon initiates translation. **For these codons, which give the orders to stop translation, there are no corresponding tRNAs with amino acids.  Initiation of Protein Synthesis - Involves ribosome subunits 1 and numerous additional molecules N-formylmethionine-tRNA – bacterial initiator tRNA archaea and eukaryotes use methionine-tRNA Initiati on Elongati on Elongation Cont.