Bacterial Genetics 121

• Genotype


  Sum of all types of genes; genetic make up
• Phenotype


  Expression of genotype creates traits (structures and functions)
• Phenotype can change depending on which genes are expressed (turned on)
• DNA


  • General structure is universal
  • Composed of building blocks called deoxyribonucleotides
  • Two strands are complementary oriented in opposite directions (5' to 3')

  
• Deoxyribonucleotide


  • 5-carbon sugar (2-deoxyribose)
  • Phosphate group
  • Nitrogenous base
• Nitrogenous bases


  • Purine bases – guanine, adenine
  • Pyrimidine bases – cytosine, thymine
• DNA Replication


  1. Origin of replication

  2. Helicases break the H bonds

  3. Single-stranded binding proteins keep the strands apart

  4. DNA pol III; RNA primase added a short length of RNA

  
• RNA


  • Similar in structure to DNA but is single-stranded
  • Each ribonucleotide has 5-carbon sugar (ribose), phosphate group, and nitrogenous base
  • Three functionally different types: mRNA, rRNA, tRNA

  
• Nitrogenous bases in RNA

  • Purine bases – guanine, adenine
  • Pyrimidine bases – cytosine, uracil
• Lactose (lac) Operon

  • Regulator
  • Control locus
  • Structural locus
• Horizontal gene transfer in bacteria

  1. Conjugation

  2. Transformation

  3. Transduction
• Conjugation


  Exchanging genes
• Transformation


  Capturing DNA from solution
• Categories of mutations


  • Point mutations
  • Frameshift mutations
  • Insertion mutations
  • Deletion mutations
• Analysis of DNA


  Polymerase chain reaction
• Recombinant DNA Technology


  Technical aspects of recombinant DNA and gene cloning

  
• Genotype


  Sum of all types of genes; genetic make up
• Phenotype


  Expression of genotype creates traits (structures and functions)
• Phenotype can change depending on which genes are expressed (turned on)
• Central Dogma


  Genotype (genetic information) -> Phenotype (result of expressing the genetic information)
• DNA


  • General structure is universal
  • Composed of deoxyribonucleotides (5-carbon sugar, phosphate, nitrogenous base)
  • Two strands are complementary oriented in opposite directions (5' to 3')

  
• Nitrogenous bases


  Purines (guanine, adenine) and pyrimidines (cytosine, thymine)

  
• DNA Replication


  1. Origin of replication

  2. Helicases unwind DNA

  3. Single-stranded binding proteins keep strands apart

  4. DNA pol III and RNA primase add new nucleotides

  
• RNA


  • Similar in structure to DNA but is single-stranded
  • Three functionally different types: mRNA, rRNA, tRNA

  
• Nitrogenous bases in RNA

  Purines (guanine, adenine) and pyrimidines (cytosine, uracil)

  
• Lactose (lac) Operon


  • Regulator gene
  • Control locus (promoter, operator)
  • Structural locus (3 genes coding for enzymes)
• Phase Variation


  Reversible switching between two or more phenotypic states
• Horizontal gene transfer in bacteria

  1. Conjugation

  2. Transformation

  3. Transduction
• Conjugation


  Exchanging genes through direct cell-to-cell contact
• Transformation


  Capturing DNA from solution

  
• Transduction


  Transfer of genetic material from one bacterium to another by a bacteriophage
• Transposons


  Genetic elements that can move around and insert themselves into different locations within the genome
• Causes of mutations


  • Errors during DNA replication
  • Exposure to mutagens (chemicals, radiation)
• Categories of mutations


  • Substitution
  • Deletion
  • Insertion
  • Frameshift
• Repair of mutations


  DNA repair mechanisms
• Genetic Engineering


  • Recombinant DNA technology
  • Analysis of DNA (PCR, gene cloning)
• Polymerase Chain Reaction (PCR)

  1. Denaturation

  2. Annealing

  3. Extension
• Recombinant DNA Technology


  Combining DNA from different sources to create new genetic combinations
• Gene Cloning


  1. Inserting a gene of interest into a vector

  2. Transforming host cells

  3. Selecting and amplifying transformed cells
• Genetics – study of inheritance (heredity) of living things