Genetic Control of Metabolism Flashcards
How can wild strains of micro-organisms be improved?
Wild strains of micro-organisms can be
improved by mutagenesis, or recombinant
DNA technology.
What factors contribute to mutation?
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-organism.
What does recombinant DNA technology involve?
Recombinant DNA technology involves the use of recombinant plasmids and artificial chromosomes as vectors.
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.
What is an artificial chromosome?
Artificial chromosomes are preferable to
plasmids as vectors when larger fragments of foreign DNA are required to be inserted.
Explain the role of enzyme restriction endonucleases and ligase in recombinant DNA technology?
- Restriction endonucleases cut open plasmids and specific genes out of chromosomes, leaving sticky ends.
- Complementary sticky ends are produced when the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome. Ligase seals the gene into the plasmid.
What do recombinant plasmids and artificial chromosomes contain?
- restriction sites
- regulatory sequences
- an origin of replication
- selectable markers
Describe what a ‘restriction site’ is?
Restriction sites contain target sequences of DNA where specific restriction endonucleases cut.
Describe ‘regulatory sequences’
Regulatory sequences control gene expression.
Describe the ‘origin of replication’
An origin of replication allows self replication of the plasmid/artificial chromosome.
Describe what a ‘selectable marker’ is?
Selectable markers such as antibiotic
resistance genes protect the microorganism from a selective agent (antibiotic) that would normally kill it or prevent it growing.
Describe a selectable marker present in a vector.
Selectable marker genes present in the
vector ensure that only micro-organisms
that have taken up the vector grow in the
presence of the selective agent (antibiotic).
Describe the safety mechanisms put in place regarding the micro-organism?
As a safety mechanism, genes are often
introduced that prevent the survival of the
micro-organism in an external environment.
