GENETIC CONTROL OF METABOLISM U2 Flashcards
State the 2 ways in which wild strains of micro-organisms can be improved
The two ways in which wild strains of micro-organisms can be improved are:
Mutagenesis
Recombinant DNA technology
Describe Mutagenesis
Mutagenesis is exposing micro-organisms to UV light and other forms of radiation or mutagenic chemicals resulting in mutations.
Some mutations may produce an improved strain of micro-organism.
Example
Using radiation or UV to induce mutations, most mutations will be harmful, however some will be beneficial that improves the micro-organism these then can be collected and analysed.
State what is involved in Recombinant DNA technology
Recombinant DNA technology involves the use of:
Recombinant Plasmids
Artificial chromosomes
Describe a vector
A vector is a DNA molecule used to carry foreign genetic information into another cell.
Artificial chromosomes and plasmids are examples of vectors used in recombinant DNA technology.
Artificial chromosomes are preferable to plasmids as vectors when larger fragments of foreign DNA are required to be inserted.
Describe the role of restriction endonucleases and ligases in recombinant DNA technology
Restriction endonucleases cut open plasmids and leave STICKY ENDS.
Complementary specific ends (sticky ends) are produced when the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome.
Ligase will seal the gene into the plasmid.
The four components that a plasmid or artificial chromosome must contain?
Restriction sites
Regulatory sequences
Origin of replication
Selectable markers.
Restriction Sites
contain target sequences of DNA where specific restriction endonucleases cut.
Regulatory sequences
control gene expression.
Origin of replication
allows for self-replication of the plasmid/artificial chromosome.
Selectable markers
such as antibiotic resistance genes protect the micro-organism from a selective agent (antibiotic) that would normally kill it or prevent it from growing. The selectable marker gene ensures that only the micro-organisms that have taken up the vector grow in the presence of the selective agent (antibiotic).
Describe the safety mechanism often used in recombinant DNA technology
Genes are often introduced that prevent the survival of the micro-organism in an external environment.
Example
the gene inserted into the micro-organism means it may not be able to produce a certain metabolite which is provided within the laboratory. This means the micro-organism will not be able to survive outside the laboratory because of the failure to produce this metabolite.
Explain the use of recombinant yeast cells in recombinant DNA technology
Recombinant yeast cells may be used, as plant or animal recombinant DNA expressed in bacteria may result in polypeptides being incorrectly folded.
Recombinant yeast cells will produce active forms of the protein which would have been inactive in bacteria.
(Remember, yeast cells contain plasmids but are eukaryotic cells and contain protein folding equipment that bacteria do not have).
