Genetic control of metabolism Flashcards
How to improve the strain you are using?
mutagenesis;
recombinant DNA.
Mutagenesis?
The process of creating mutants by exposing microorganisms to mutagens, for example UV light, the rate of mutagenesis can be increased. These mutants can then be cultured and used in the lab.
Although this seems a relatively straightforward way to produce a desirable characteristic in a microorganism, mutant strains tend to be genetically unstable. This means they are likely to revert back to their wild type (normal) phenotype.
Selective breeding
Selective breeding involves sexual reproduction between two strains of microorganism, each with a desirable characteristic. The aim of selective breeding is to produce offspring which have a new genotype and that show both desirable characteristics. Selective breeding can take a long time to achieve the desired result as it is also likely that undesirable characteristics will combine and show up in the phenotype of the offspring.
Recombinant DNA technology?
Recombinant DNA technology refers to the ability of scientists to manipulate the genome of an organism by introducing new gene sequences. New gene sequences can be transferred between individuals of the same species or from one species to another. Using recombinant DNA technology, it is possible to artificially improve a strain of microorganism.
What is added a safety mechanism to recombinant dna?
As a safety mechanism, genes are often introduced that prevent the survival of the microorganism in an external environment.
How to introduce a gene into an organism?
In order to introduce a gene into an organism, scientists must use a vector.
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.
Difference between recombinant plasmids and artificial chromosomes?
Recombinant plasmids and artificial chromosomes share many features, but plasmids are only capable of carrying relatively small quantities of DNA whereas artificial chromosomes can carry longer DNA sequences.
Recombinant plasmids and artificial chromosomes contain the what features which allow them to operate effectively?
electable markers - such as antibiotic resistance genes protect the micro-organism from a selective agent (antibiotic) that would normally kill it or prevent it growing. 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);
restriction sites - contain target sequences of DNA where specific restriction endonucleases cut;
origin of replication - allows self-replication of the plasmid/artificial chromosome;
regulatory sequences - control expression of the inserted gene as well as other genes found on the vector.
The manipulation of DNA involves the use of what two types of enzyme?
restriction endonuclease and ligase
What are restriction endonuclease?
restriction endonucleases are enzymes that cut specific target sequences of DNA. There will be complementary sequences opposite on the other strand of DNA, which is also cut by the enzyme. These ends could re-join by base-pairing with each other or with similar sticky ends from another source.
Why can it be difficult to express animal or plant (eukaryotic) genes successfully in bacterial cells?
Bacterial proteins do not undergo the same post-transcriptional and post-translational modifications which eukaryotic proteins do. Expression of plant or animal genes in bacteria may result in polypeptides that are folded incorrectly and are therefore non-functional
