2.7 genetic control of metabolism Flashcards
How can wild strains of microorganisms be improved?
- mutagenesis
- recombinant DNA technology
Explain how mutagenesis works
- exposure to UV light and other forms of radiation or mutagenic chemicals result in random mutations
- some of which may produce an improved stain of microorganism with desirable qualities
What is recombinant DNA technology?
the use of recombinant plasmids and artificial chromosomes as vectors
What is a vector?
- a DNA molecules used to carry foreign genetic information into another cell
- both plasmids and artificial chromosomes are used as vectors
When are artificial chromosomes preferred to plasmids as vectors?
when larger fragments of foreign DNA are require to be inserted
What is the role of the enzyme restriction endonuclease?
-cut open plasmids and cut 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 cut the gene from the chromosome.
What is the role of Ligase in in recombinant DNA technology?
ligase seals the gene into the plasmid
- to seal complimentary DNA fragments into place
- complementary DNA fragments are required to insert them into a plasmid or chromosome
What are the five different sections to recombinant plasmids and artificial chromosomes?
- restriction sites
- regulatory sequences
- origin of replication
- selectable marker gene
- safety gene
What is a restriction site?
- contain target sequences of DNA where
- specific restriction endonuclease cut (the same one used to extract the gene from the chromosome)
- leaving sticky ends
What is a regulatory sequence?
DNA sequence which controls gene expression
What is the origin of replication?
allows self-replication of the plasmid/artificial chromosome
What are selectable marker genes?
- protect the microorganism from a selective agent that would normally kill it or prevent it growing
- ensures that only the micro-organisms which have taken up the vector grow in the presence of the selective agent
What safety mechanism is often used in recombinant DNA technology?
genes are introduced that prevent the survival of the microorganism in an external environment
Why are recombinant yeast cells used in recombinant DNA technology?
- plant or animal recombinant DNA expressed in bacteria may result in polypeptides being incorrectly folded
- recombinant yeast cells produce active forms of the protein which are inactive in bacteria
What is mutagenesis?
the process of inducing mutations
What could improved microorganisms refer to when being used in an industry setting?
- cultured in a low cost medium
- production of required product is increased
How can microorganisms be transformed?
by transferring plant or animal gene sequences to them
What is the definition of recombinant DNA technology?
the joining together of DNA molecules from two different species
What gene sequences can be transferred to microorganisms? and to produce what?
- plant or animal gene sequences
- produce plant or animal proteins
describe the process of genetic engineering?
-DNA is extracted and then the required gene is cut out using restriction endonuclease
- isolation of bacterial plasmid
- plasmid extracted and cut open using the same restriction endonuclease
- DNA ligase seals required gene into plasmid
- recombinant plasmid taken up by host cell
- host cell then replicates itself
What can plant or animal recombinant DNA expressed in bacteria result in?
the production of polypeptides that are folded incorrectly and are non-functional
