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Chapter 5

Chapter 5. Microbial Genetics. Terminology. Genetics: The study of what genes are, how they carry information, how information is expressed, and how genes are replicated. Gene: A segment of DNA that encodes a functional product, usually a protein. Terminology.

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Chapter 5

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  1. Chapter 5 Microbial Genetics

  2. Terminology • Genetics: The study of what genes are, how they carry information, how information is expressed, and how genes are replicated. • Gene: A segment of DNA that encodes a functional product, usually a protein.

  3. Terminology • Genome: All of the genetic material in a cell • Genomics: The molecular study of genomes • Genotype: The genes of an organism • Phenotype: Expression of the genes

  4. Q&A E. coli is found naturally in the human large intestine, and there it is beneficial. However, the strain designated E. coli O157:H7 produces Shiga toxin. How did E. coli acquire this gene from Shigella?

  5. Chromosome Map Figure 8.1b

  6. Determine Relatedness Clinical Focus, p. 223

  7. Determine Relatedness Which strain is more closely related to the Uganda strain?

  8. The Flow of Genetic Information Figure 8.2

  9. DNA • Polymer of nucleotides: Adenine, thymine, cytosine, and guanine • Double helix associated with proteins • "Backbone" is deoxyribose-phosphate • Strands are held together by hydrogen bonds between AT and CG. • Strands are antiparallel. Figure 8.3b

  10. DNA Figure 8.3a

  11. DNA Figure 8.4

  12. DNA • DNA is copied by DNA polymerase • In the 5' 3' direction • Initiated by an RNA primer • Leading strand is synthesized continuously • Lagging strand is synthesized discontinuously • Okazaki fragments • RNA primers are removed and Okazaki fragments joined by a DNA polymerase and DNA ligase

  13. Important Enzymes Table 8.1

  14. DNA Replication Figure 8.5

  15. DNA • DNA replication is semiconservative. Figure 8.6

  16. Transcription • DNA is transcribed to make RNA (mRNA, tRNA, and rRNA). • Transcription begins when RNA polymerase binds to the promotor sequence • Transcription proceeds in the 5' 3' direction • Transcription stops when it reaches theterminator sequence

  17. Transcription Figure 8.7 (1 of 2)

  18. Transcription Figure 8.7 (2 of 2)

  19. RNA processing in Eukaryotes Figure 8.11

  20. The Flow of Genetic Information Figure 8.2

  21. Translation • mRNA is translated in codons (three nucleotides) • Translation of mRNA begins at the start codon: AUG • Translation ends at a stop codon: UAA, UAG, UGA Figure 8.2

  22. Translation Figure 8.8

  23. Translation Figure 8.10

  24. Translation Figure 8.9, step 1

  25. Translation Figure 8.9, step 2

  26. Translation Figure 8.9, step 3

  27. Translation Figure 8.9, step 4

  28. Translation Figure 8.9, step 5

  29. Translation Figure 8.9, step 6

  30. Translation Figure 8.9, step 7

  31. Translation Figure 8.9, step 8

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