2.7 Genetic Control of Metabolism Flashcards
(16 cards)
How can wild strains of micro-organisms be improved?
By mutagenesis, or recombinant DNA technology
What results in mutations?
Exposure to UV light and other forms of radiation or mutagenic chemicals, some of these mutations may produce an improved strain of micro-organism
What is involved in recombinant DNA technology?
The use of recombinant plasmids and artificial chromosomes as vectors
What is a vector?
A DNA molecule used to carry foreign genetic information from one cell into another cell. Artificial chromosomes are used as vectors during recombinant DNA technology
When would artificial chromosomes be preferred as vectors to plasmids?
When larger fragments of foreign DNA are required to be inserted
What is the role of restriction endonuclease in recombinant DNA technology?
They cut open plasmids and specific genes out of chromosomes, leaving sticky ends
When are complementary sticky ends produced?
When the same restriction endonuclease is used to cut open the plasmid and the gene from the chromosome.
What seals the gene into the plasmid in recombinant DNA technology?
Ligase enzyme
What are recombinant plasmids and artificial chromosomes made up of?
Restriction sites, regulatory sequences, an origin of replication and selectable markers
What is the role of the restriction site?
Contains target sequences of DNA where specific restriction endonucleases cut
What is the role of the regulatory sequences?
Control gene expression
What is the role of the origin of replication?
Allows self-replication of the plasmid/artificial chromosome
What is the role of the selectable markers?
Protect the micro-organism from a selective agent that would normally kill it or prevent it growing
E.g. antibiotic resistance genes protect the micro-organism from antibiotics
What do selectable marker genes do when they are present in vectors?
Ensure that only micro-organisms that have taken up the vector grow in the presence of the selective agent
What safety mechanism is carried out in recombinant DNA technology?
Genes are often introduced that prevent the survival of the micro-organism in an external environment
Why might recombinant yeast cells be used in recombinant DNA technology?
To produce active forms of the protein which are inactive in bacteria. Plant or animal recombinant DNA expressed in bacteria may result in polypeptides being incorrectly folded
