Introduction of topic I will use a dendogram

Introduction:

Antibiotic Resistance Explained

Variation and evolution

• Darwin, Alfred Russel WallaceLamark

  • the mechanism of inheritance was poorly understood

  • did not explain satisfactorily the nature of the variation in the population.

    1 variation occurs naturally within a species;

    2 some variants are better (or less well) suited to a specific environment;

    3 variants that are better suited to the environment will grow, multiply

    and survive better;

    4 if two populations of the same species are separated (e.g. geographically), they will diverge as they become better adapted to their different

    environments;

    5 eventually, the differences between the two populations will be sufficient for us to call them different species.

    EVOLUTION IS NOT NAMED AS THEORY BECAUSE IS SPECULATIVE, BUT CAUSE IT IS SYNTHESIS OF IDEAS

Mendel

• a combination of discrete units rather than a blend of the characteristics of the parent.
  • Bacterial Chromosome (genes as units)
• As for the nature of variation, although it subsequently became a central dogma that variation is essentially a random process that occurs without being influenced by the environment

Bacterial Growth and the probability of mutation

Short Generation time

Assexual reproduction

Genetic exchange (other lecture)

• Example: PZA resistance Happened before the introduction of PZA

• How mutation happens in tuberculosis polichemotherapy

The Evolution of Bacteria on a "Mega-Plate" Petri Dish (Kishony Lab)

At inhibitory/sub inhibitory concentration bacteria has the growth arrested, there is low killing rate, so this allow favorable mutations (which may include some form of DNA replication (e.g. connected with DNA repair).

• correct drug intake
• Early treatment of infection
• Exemplify again with mutations rates over different mycobacterial drugs

Mechanisms of mutation

The basic processof replication involves polymerizing, or linking the nucleotidesof DNA into longer chains or strands

• Spontaneous mutation

  • Experimental insight: how a parental and mutant strain behaves under a same conditioning?

  • toutomerism (mismatch)

  • proofreading mechanism of DAN polymerase

  • existence of proofreading and other repair mechanisms that keeps the mutation rate low.

  • mutator strains

    • Experimental insight: how each particular mechanism impact mutation rates for different selection agents

  • Chemical mutagens

    • Experimental insight: they enhance the frequency of mutation
    • ethyl methane sulphonate
    • 1-methyl-3-nitro-1-nitroso-guanidine (MNNG)
    • acridine orange and ethidium bromide

  • Ultraviolet irradiation

    • The principal effect of UV irradiation with which we are concerned is the

    production of pyrimidine dimers

    r

  Editing mechanism of DNA polymerase

SOS repair