Lectures 15-18 Flashcards
What are the three mechanisms of genetic exchange in prokaryotes
Transformation, transduction and conjugation
What is transformation
Transformation is the uptake of naked DNA where receptor molecule is required. Lab work is also required to make competent cells and identify transformants
What is transduction
Transduction is the transfer of DNA from one cell to another by a bacteriophage. Generalised transduction ia DNA derived from the host is packaged inside virion. Specialised transduction is specific DNA of host integrated directly into virus genome
What is conjugation
Conjugation is transfer of DNA by mating (cell to cell contact), donor cells contain plasmid and receptor cell doesn’t
What are transposable elements?
Discrete segment of DNA that move as a unit from one location to another within chromosomes, the two main types are transponsons and insertion sequences. They move by a process called transposition
What is CRISPR-Cas
CRISPR is a type of prokaryotic immune system, which is a region of bacterial chromosome DNA similar to foreign DNA (spacers), Cas proteins store these spacers and kill recognized foreign DNA
What are the advantages of microbio technology over chemical processes
Use of renewable sources Low energy consumption Less side products Low enviromental pollution Production of complex compounds
What are methods of genetic engineering
Restriction Enzymes - recognise specific DNA sequences and cleave those sites (protect against foreign DNA)
Cloning - Restriction enzyme plasmid insert transform
Hosts - E.coli major host for using hosts
What is mammalian protein expression
mammalian proteins genetically engineered like insulin
What is pathway engineering
The process of assembling a new or improved biochemical pathway using genes from one or more organisms
What are biofilms
Group of bacterial cells connected to surface and enclosed in a matrix excreted by the cells. Biofilms protect the cells from detachment and keep nutrients inside
Why are biofilms created
Self defence against physical factors (cant be detached) and toxins, allow cells to stay in favourable niche and allow cells to live in close proximity
Describe how biofilms are made by p.aeruginosa
Attachment - cells attach to surface
Colonization - intracellular communication (quorom sensing), growth and polysaccharide formation
Development - more growth and polysaccharide formation
Active dispersal - cells disperse by environmental factors like nutrient availability
Explain how generalised transduction is used to move resistance marker genes from a donor E.coli strain to a recipient strain
Firstly the phage is put inside E.coli strain where lytic cycle occurs (enters and takes over cell, replicates then explodes cell). The recipient strain is then infected with the stock made from before. Homologous recombination occurs and then select for antibiotic using replica plating.
Compare and contrast 3 main types of microbes used as cloning hosts for recombinant protein expression
E.Coli most commonly used as it is low costing and is best known bacteria. However, its pathogenic potential and its periplasmic traps proteins
Bacillus subtillis is easily transformed and non pathogenic but genetically unstable and less developed than E.coli
S.cerevissae is well developed, non pathogenic but plasmids unstable and will not replicate most bacterial plasmids
