Fast

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Fast Cheap Bacteria Sex
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Bacteria

• 2 Domains
• Archea Bacteria (eubacteria)
• Prokaryotes
• Cells with no true nucleus
• Successful diverse
• 3.5-3.6 BYo
• 1/3 of earths biomass
• Asexual reproduction
• How do they persist given low genetic diversity
  lack of mutation filtering system

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3 Domains
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Prokaryotes Who Are They??

• Germs, Bugs, Bacteria
• Disease
• The bad guys???

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Bubonic Plague
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Food Poisoning
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They Can Also
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Photosynthesis
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Fermentation
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Nutrient Cycling
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100,000 spp
Your body-1000 billion animal cells
10,000 billion bacteria cells
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Diverse Niches

• Everywhere!
• Extreme temperatures
• High salt concentrations
• Acidic/ alkali conditions

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Bacteria Live in Every Possible location on
Earth!
New Species of Ancient Bacteria Discovered 2
Miles Deep in Greenland Glacier
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Dominate Life on Earth
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Prokaryotes

• Earliest life on earth (3.5-3.6 byo)
• Building blocks of life
• Master Networkers Symbiosis
• Genetic engineering
• Origin of aerobic other respirations
• Origin of several types of photosynthesis
• Origin of cell wall

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How Do They Do It???
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Bacterial DNA is Dynamic

• 2 forces act on bacterial DNA
• Selection for shorter length
• Favors DNA loss
• i.e. keep it simple
• Selection for gene function
• Drives acquisition of exogenous DNA

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Bacteria DNA

• Genophore
• Single double strand
• ring
• Very dynamic
• Smaller less complex DNA
• Lower amounts of associated proteins
• Contains Information for essential functions

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Bacteria Structure
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Bacteria Accessory DNA

• Plasmid
• Smaller rings of DNA
• Contain fewer number of genes
• Codes for non vital functions
• Accessory DNA
• Specialized functions to accommodate
  environmental conditions
• Metabolism of unusual nutrients
• Adaptations to novel stimuli/ conditions
• Production of toxins
• Resistance to antibiotics
• Replicate independently

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Plasmid DNA Good in a Pinch!
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Bacteria Reproduction

• Binary fission
• Fast, cheap
• Some bacteria once every 20 min
• Bacteria introduce vast amts of variation
  extensively w/in a few years
• Eukaryotes via mutation MYS

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Binary Fission
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Bacteria Sexual Reproduction

• Sex is the Exchange genetic material from
  different individuals into a common cell
• Sex in bacteria occurs by uptake of exogenous DNA
• Horizontal gene transfer
• No gamete fusion or reproduction
• Alters existing genes

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Increased Diversity

• Bacteria sex introduces variation in 2 ways
• Introduces novel gene sequences
• Alters existing genetic material

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When do Bacteria Have Sex

• Response to environmental stress
• Nutrient shortage/ starvation
• Altered growing conditions
• Cell density (quorum sensing)

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How Do Bacteria Have Sex?

• Bacterial mechanisms for Introducing Variation
• Mutation
• Conjugation
• Transformation
• Transduction

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Mutation

• Error in DNA sequence
• Often occurs during replication of DNA
• Can be caused by a mutagen
• Ex. UV, Chemicals
• Can be deleterious or beneficial
• Rapid way to introduce diversity

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Mutations are Relatively Common
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Conjugation

• Process by which bacteria join to exchange
  genetic material
• Exchange plasmid DNA
• Uses conjugation pili
• Forms bridge between two bacterial cells

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Bacteria Conjugation
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Bacteria Conjugation
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Transduction

• Indirect exchange of DNA between individuals
• Utilizes a virus
• Bacteriophage
• Virus life cycle transfers bacteria DNA from one
  individual to another

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Virus
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How Does a Virus Work?
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Transformation

• Direct exchange of DNA fragments
• Replaces homologous chromosome sequences
• Restores genes lost or degraded in populations
• Adds diversity
• Aids in repair of deleterious mutations
• Can occur intraspecifically interspecifically
• Intraspecific transformation
• Increases changes in allele frequency more
  frequently than by mutation
• Bacteria analogue of Meiotic sex (recombination)

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Transformation
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Cost of Transformation

• Mechanics of DNA uptake requires energy
• Risk incorporating defective alleles
• What are the advantages.

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Bacteria Species are Metapopulations

• Bacteria form spatially distinct populations
  living under varied ecological conditions
• Ie distinct selection forces
• Can lose alleles that may be useful when
  conditions change
• Remember NS favors smaller genomes
• Transformation helps populations restore lost or
  degraded (mutated) alleles

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Superorganism

• Can exchange w/ virtually any other bacteria
• Essentially have access to a single gene pool
  hence to the adaptive mechanism of the entire
  bacteria kingdom