L45- intro to prokaryotic genetics

• Why do we study bacterial genetics?

  To understand molecular biology and human health
• What are the key milestones in the timeline of genetics?

  • 1850: Darwin's early work
  • 1866: Mendel's work on peas
  • 1941: Beadle and Tatum's one gene one enzyme
  • 1953: Hershey & Chase confirm DNA function
  • 2003: The Human Genome Project completion
• What is bacterial genetics?

  Study of heritable information in bacteria
• What techniques enable the study of bacterial genetics?

  Culture, mutagenesis, transformation, conjugation
• What percentage of DNA on Earth is estimated to be bacterial DNA?

  30%
• How many bacterial cells are estimated to be in the human body?

  Approximately equal to eukaryotic cells
• Why are bacteria considered good model organisms?

  They are haploid and reproduce asexually
• What is the structure of the bacterial genome?

  A single circular, double-stranded DNA chromosome
• What is unique about Borrelia burgdorferi's genome?

  It has a linear, single chromosome
• What are operons in bacterial genomes?

  Groups of functionally related genes
• How long is the E. coli genome?

  4.6 Mbp
• What is binary fission?

  Asexual reproduction in prokaryotes
• What happens during binary fission?

  Cell elongates, DNA replicates, divides
• What is the generation time of E. coli under optimal conditions?

  Approximately 20 minutes
• What are the growth requirements for E. coli?

  Simple inorganic nutrients and carbon source
• Who discovered Escherichia coli?

  Theodor Escherich
• What is a prototroph in E. coli?

  Wild type that does not require special nutrients
• What are auxotrophic mutants?

  Mutants impaired in metabolic capabilities
• What do biosynthetic auxotrophs require?

  Additional nutrients to grow
• What are catabolic auxotrophs?

  Mutants that cannot catabolize certain carbon sources
• What are housekeeping genes?

  Essential genes for E. coli survival
• What are conditional lethal mutants?

  Mutants lethal under specific conditions
• What are temperature-sensitive mutants?

  Mutants that grow only at permissive temperatures
• What is gene annotation?

  Indicates biochemical pathways and gene products
• How is protein nomenclature different from gene nomenclature?

  Proteins are capitalized, genes are not
• What does a superscript minus sign indicate in nomenclature?

  Mutant phenotype requiring specific nutrients
• What are the key components of bacterial nomenclature?

  • Three-letter codes for amino acids
  • Common carbon sources
  • Nucleotides and vitamins
  • Gene and protein distinctions
• What is the effect of losing anabolic pathways?

  Loss of ability to make specific molecules
• What happens when a catabolic pathway is lost?

  Loss of ability to break down specific molecules
• What do drug-resistance genes indicate?

  Resistance to specific antibiotics or phages
• What do superscripts and subscripts in nomenclature provide?

  Additional information about mutations
• What does the Δ symbol indicate in nomenclature?

  Deletion of a gene or sequence
• What is the significance of the + and - symbols in nomenclature?

  Indicates whether a gene requires specific nutrients
• What does the term "lysogenized" refer to?

  Incorporation of a phage into the bacterial genome