1 / 22

Prof. Dr. Samih Tamimi

Prof. Dr. Samih Tamimi. Chapter 16 and 17 Notes. Chapter 16 . People: 1. Griffith - studied bacteria - heat killed cells (bacteria) were able to take in material from living cells that were not harmful (bacteria) - mixture would kill the mice - bacteria cells were transformed

shel
Download Presentation

Prof. Dr. Samih Tamimi

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Prof. Dr. SamihTamimi Chapter 16 and 17 Notes Biology 1 Al-Ahlya Amman University

  2. Chapter 16 People: 1. Griffith - studied bacteria - heat killed cells (bacteria) were able to take in material from living cells that were not harmful (bacteria) - mixture would kill the mice - bacteria cells were transformed 2. Avery - announced transformation agent was DNA 4. Chargaff - identified 4 nitrogen bases: adenine, thymine, guanine, cytosine - base pairing rules: A-T, C-G - % of A = % of T, % of C = % of G 6. Watson and Crick – model for DNA molecule Biology 1 Al-Ahlya Amman University

  3. Nitrogenous bases Sugar–phosphate backbone 5 end Structure of the double helix one side of DNA with bases Thymine (T) 5’ carbon attached to phosphate group Adenine (A) 3’ carbon attached to hydroxyl group Cytosine (C) DNA nucleotide Phosphate Sugar (deoxyribose) 3 end Guanine (G) Biology 1 Al-Ahlya Amman University

  4. The double helix Monomer of nucleic acid: 3 parts to a nucleotide: 1. 2. 3. nucleotide phosphate sugar -DNA (deoxyribose) base - purines - pyrimidines Biology 1 Al-Ahlya Amman University

  5. Purines - - - Pyrimidines - - - Bonds that connect bases: double ringed bases adenine guanine single ringed bases cytosine thymine hydrogen bonds Biology 1 Al-Ahlya Amman University

  6. complementary base pairing A - T C - G A T A T A T A T C G C G C G C G A T A T A A T T T A T A T T A A C C G C G C G G (c) “Daughter” DNA molecules, each consisting of one parental strand and one new strand (b) Separation of strands (a) Parent molecule Biology 1 Al-Ahlya Amman University

  7. First replication Second replication Parent cell (a) Conservative model Semiconservative model: the old strand makes a new strand (b) Semiconserva- tive model (c) Dispersive model Biology 1 Al-Ahlya Amman University

  8. Origin of replication Parental (template) strand bacterial DNA Daughter (new) strand Replication fork Double- stranded DNA molecule Replication bubble 0.5 µm Two daughter DNA molecules (a) Origins of replication in E. coli Origin of replication Double-stranded DNA molecule Parental (template) strand Daughter (new) strand 0.25 µm Replication fork Bubble Two daughter DNA molecules (b) Origins of replication in eukaryotes Biology 1 Al-Ahlya Amman University

  9. Antiparallel - side chains of DNA run in DNA elongates only in the 5’ 3’ 3’ 5’ opposite directions 5’ 3’ direction New strand 5 end Template strand 3 end 5 end 3 end Sugar T A A T Base Phosphate C G C G G C G C DNA polymerase 3 end A A T T 3 end Pyrophosphate C C Nucleoside triphosphate 5 end 5 end Biology 1 Al-Ahlya Amman University

  10. ligase – covalently connects DNA nucleotides helicase - unwinds double helix ssbp’s – stabilize unwound DNA Overview primase – synthesizes RNA primer Origin of replication Lagging strand Leading strand Leading strand Lagging strand Single-strand binding protein Overall directions of replication Helicase Leading strand 5 DNA pol III 3 3 Primer Primase 5 3 Parental DNA Lagging strand DNA pol III 5 DNA pol I DNA ligase 4 3 5 3 2 1 3 5 DNA polymerase III – synthesizes new DNA on 3’ end DNA polymerase I – removes primers and brings in DNA nucleotides Biology 1 Al-Ahlya Amman University

  11. Biology 1 Al-Ahlya Amman University

  12. CHAPTER 17 DNA TRANSCRIPTION Transcription – synthesis of mRNA Ribosome RNA from DNA TRANSLATION Polypeptide Prokaryotic cell Nuclear envelope makes mRNA (messenger) • Compartmentalization of • transcription and • translation • provides an opportunity • to • *bacteria • - DNA TRANSCRIPTION Translation – synthesis of a polypeptide - - Pre-mRNA RNA PROCESSING from mRNA mRNA modify mRNA before it leaves the nucleus occurs on ribosome Ribosome do not have this TRANSLATION uses tRNA Polypeptide no nucleus Eukaryotic cell Biology 1 Al-Ahlya Amman University

  13. Gene 2 DNA molecule Gene 1 Gene 3 1 gene codes for one protein (polypeptide) ** - -codon- -start codon: 5¢ 3¢ DNA strand (template) gene/protein results in the organisms phenotype TRANSCRIPTION 3 consecutive bases on mRNA 5¢ 3¢ mRNA Codon TRANSLATION AUG (methaionine) Protein Amino acid 20 different amino acids Biology 1 Al-Ahlya Amman University

  14. Second mRNA base First mRNA base (5 end of codon) Third mRNA base (3 end of codon) Biology 1 Al-Ahlya Amman University

  15. Promotor region: a start point for RNA polymerase also determines which strand will be Promoter Transcription unit copied 5 3 3 5 DNA Start point RNA polymerase Initiation Nontemplate strand of DNA 1 Elongation RNA nucleotides 5 3 RNA polymerase 5 3 Template strand of DNA RNA transcript Unwound DNA 3 Elongation 2 3 end Rewound DNA 5 3 5 3 5 3 5 5 Direction of transcription (“downstream”) RNA transcript Template strand of DNA Termination 3 Newly made RNA 3 5 5 3 5 3 Completed RNA transcript Biology 1 Al-Ahlya Amman University

  16. 3 Amino acid attachment site tRNA – transfers amino acids from the cytoplasms pool to 5 a ribosome Hydrogen bonds anticodon – complementary to the codon on mRNA Anticodon (a) Two-dimensional structure Amino acid attachment site 5 3 Hydrogen bonds 3 5 Anticodon Anticodon (c) Symbol used in this book Biology 1 Al-Ahlya Amman University (b) Three-dimensional structure

  17. Aminoacyl-tRNA synthetase (enzyme) Amino acid P P P Adenosine ATP connecting an amino acid to tRNA P Adenosine tRNA P P i Aminoacyl-tRNA synthetase P i P i tRNA P Adenosine AMP Computer model Aminoacyl-tRNA (“charged tRNA”) Biology 1 Al-Ahlya Amman University

  18. Synthesis of proteins: A site – P site – E site – Amino acids incoming Polypeptide tRNA with amino acid attached growing polypeptide Ribosome exit site tRNA Anticodon Codons 5¢ 3¢ mRNA Biology 1 Al-Ahlya Amman University

  19. Growing polypeptide Exit tunnel tRNA molecules Ribosome - - Large subunit E P A 2 subunits Small subunit rRNA and protein 5 3 mRNA (a) Computer model of functioning ribosome Functional ribosome: - small - add - large P site (Peptidyl-tRNA binding site) ribosomal unit A site (Aminoacyl- tRNA binding site) E site (Exit site) E Large subunit A P mRNA binding site Small subunit mRNA and tRNA (b) Schematic model showing binding sites Growing polypeptide Amino end unit binds Next amino acid to be added to polypeptide chain -uses energy E tRNA mRNA 3 Codons 5 Biology 1 Al-Ahlya Amman University (c) Schematic model with mRNA and tRNA

  20. 3 stages for building a polypeptide: 1. Initiation Binding of mRNA to small subunit and initiator tRNA carrying met to P site with initiation codon (AUG) Then large subunit attaches Large ribosomal subunit 3 U 5 C A P site Met Met 5 3 A G U Initiator tRNA GDP GTP E A mRNA 5 5 3 3 Start codon Small ribosomal subunit Translation initiation complex mRNA binding site Biology 1 Al-Ahlya Amman University

  21. 2. Elongation Cycle Amino end of polypeptide peptide bonds are formed between amino acids Codon recognition E 3 mRNA P site A site Ribosome ready for next aminoacyl tRNA 5 GTP GDP E E P A A P Peptide bond formation GDP GTP Translocation E P A Biology 1 Al-Ahlya Amman University

  22. 3. Termination release factor attaches to stop codon, everything releases Release factor Free polypeptide 5 3 3 3 2 GTP 5 5 Stop codon (UAG, UAA, or UGA) 2 GDP Biology 1 Al-Ahlya Amman University

More Related