Genetic Control of Metabolism Flashcards
What is strain improvement by mutagenesis?
Exposure to substances that increase the chance of random change to DNA bases.
Exposure to UV light and other forms of radiation or mutagenic chemicals results in mutations, some of which may produce an improved strain of micro-organisms.
What is a vector?
A vector is a DNA molecule used to carry foreign genetic information into another cell and both plasmids and artificial chromosomes are used as vectors during recombinant DNA technology.
Recombinant DNA technology
Restriction endonucleases cuts open plasmids and specific genes out of chromosomes leaving sticky ends.
Ligase seals the gene into plasmid.
Complimentary sticky ends are produced when the same restriction endonucleases is used to cut open the plasmid and the gene from the chromosome.
What are the parts of a vector?
Restriction site
Regulatory genes
Origin of replication
Marker genes
What are restriction sites?
Restriction sites contain target sequences of DNA where specific restriction endonucleases cut.
What are regulatory genes?
Allow for control of gene expression i.e. differentiation.
Turning genes on and off
What is the origin of replication?
Origin of replication allows self-replication of the plasmid/artificial chromosome.
What are marker genes?
Deliberately inserted to check whether gene of interest has been inserted correctly.
Often DNA not successfully inserted into the plasmid.
What are selectable marker genes?
Protects bacteria from normally lethal agent.
Only bacteria with successfully taken up agent can survive.
What are antibiotic resistance markers?
This is where bacteria is exposed to antibiotics and any successful recombinant vectors with marker gene can survive.
What are safety genes?
As a safety mechanism, genes are often introduced that prevent the survival of the micro-organism in an external environment.
Bacterial vs Yeast vectors
Recombinant yeast cells may be used as plant or animal recombinant DNA expressed in bacteria may result in polypeptides being incorrectly folded.
Use of recombinant yeast cells to produce active forms of protein which are inactive in bacteria.
