2.7 Genetic Control of Metabolism Flashcards
Wild microbe strains are improved in order to what?
- Produce large quantities of target compound
- Improve genetic stability
- Improve their ability to grow on low cost nutrients
- Allow easy harvesting of target compound after fermentation is complete
What are the techniques used to improve microorganisms?
Mutagenesis and Recombinant DNA technology
What can scientists do with Recombinant DNA technology?
Transfer gene sequences from one organism to another and even from one species to another.
What is Mutagenesis?
The creation of mutants by inducing mutations.
How can the rate of mutagenesis be increased?
Exposing organisms to mutagenic agents such has UV light
What is done as a safety mechanism in Recombinant DNA tech?
Genes are often introduced that prevent the survival of the microorganism in an external environment.
What does the Restriction Endonuclease enzyme do?
- Cuts specific genes out of chromosomes of the donor organisms
- Cuts open the bacterial plasmids that are to receive the genetic information
How does the Endonuclease recognise which sequence to cut?
It recognises a specific short sequence of DNA bases called a restriction site and cuts the strand in such a way that it can leave sticky ends.
What are sticky ends?
They are produced when nucleotides are cut at different points, several nucleotides apart, and each fragment ends with a short single stranded segment.
The ends are complimentary to the new ends they will become sealed to
DNA ligase does what?
It is an enzyme which seals the gene into the plasmid to form a recombinant plasmid.
What is a Vector?
A vector is a DNA molecule used to carry foreign genetic information into another cell.
Both plasmids and artificial chromosomes are used as vectors during recombinant DNA tech.
To act as an effective vector, a plasmid must have:
- Restriction sites
- Selectable marker genes
- An origin of replication
- Regulatory sequences
What are Restriction Sites for?
To insert DNA.
It will contain target sequences f DNA where the specific restriction endonuclease cuts - same used to cut gene from chromosome. Will be complementary
What are Selectable Marker Genes for?
The are to allow identification of host cells which may have taken up the vector or not.
For example antibiotic resistant genes protect the micro-organism from a selective agent that would normally kill it or prevent it from growing.
Allows scientists to determine whether a host cell has successfully taken up the plasmid vector by ensuring the vector grows in the presence of the selective agent.
What is the Origin of Replication for?
Self - replication
The regulatory sequences control gene expression and origin of replication allows self- replication of the plasmid/artificial chromosome.
