2.3 Environmental & Genetic code of metabolism Flashcards
three domains on micro-organism
bacteria, archae, eukaryotes
why micro organisms can be used to make an range of micro organisms
micro organisms use a wide variety of substrates for metabolism and can produce a range of products from their metabolic pathways.
state three reasons why micro organisms can be used to produce a range of products
- adaptability
- ease of cultivation (growth)
- speed of growth
energy sources needed for culture of micro organisms
complex chemical molecules for biosynthesis, sterile culture, temperature, oxygen, pH.
requirements for growth (energy source) complex chemical molecules for biosynthesis
some produce amino acids, fatty acids or vitamins for biosynthesis, others require these to be supplied in the growth media e.g agar plates.
sterile culture
temperature
there will be an optimum temperature range for the particular micro organism enzyme.
oxygen
some micro organisms require a supply of oxygen by aeration for respiration. others only survive in low or no oxygen
pH
pH kept constant using buffers/buffer solution
growth phases of micro organisms
lag, log/ exponential, stationary, Death.
lag
slow increase in numbers as cells adjust to conditions. Enzymes are induced to metabolise new substrates.
log/ exponential
cell growth at most rapid rate, due to plentiful supply of nutrients. No limiting factors on their growth.
stationary
no increase in numbers. Reproduce rate = death rate. Nutrients depleted and secondary metabolites such as antibiotics produced which inhibit growth.
During the stationary stage in wild populations, secondary metabolites (antibiotics) can confer as advantage by allowing the micro organisms which produce them to out compete other micro organisms.
death
lack of nutrients in culture & accumulation of toxic metabolites leads to cell deaths.
total cell count and viable cell count
viable cell count is the living mirco organisms only. The viable cell count will show a death phase where cell numbers are decreasing.
The total cell count id the count of both viable cells and dead cells.
mutagenesis
scientists can cause wild strains of mutation in micro organisms by exposing them to UV rights or X-rays or mutagenic chemicals. This may produce a improved strain of micro organism.
As many of these mutants are genetically instable they may revert back to their original wild type after several generations.
recombinant DNA technology & vector
recombinant DNA technology involves the use of recombinant plasmids and artificial chromosomes as vectors. A vector is a DNA molecule used to carry foreign genetic information into another cell.
preferred type of vector for use in recombinant DNA technology
artificial chromosomes are preferable to plasmids as vectors when larger fragments of DNA are required to be inserted into another cell.
Recombinant DNA technology stages
1) restriction endonuclease enzyme used to
- cut out specific gene from a chromosome
- cut open a plasmid vector from bacterium.
2) same restriction endonuclease enzyme used to cut out the gene and to cut open the plasmid. This produces produce complementary “sticky ends” in the opened plasmid and at either side of the gene.
3) gene sealed into plasmid vector at complementary “sticky ends” using enzyme DNA ligase.
4) Recombinant plasmid (vector) taken up by host bacterium which synthesises required polypeptide/ protein.
restriction endonuclease enzymes in DNA recombinant technology
restriction endonuclease enzyme used to
- cut open specific gene from a chromosome
- cut open a plasmid vector from bacterium.
complementary “sticky ends”
the sticky ends of the donor DNA are complementary to the opened ends of the vector plasmid. Without complementary sticky ends the ligase would not be able to seal the gene into plasmid.
ligase
ligase is an enzyme which joins together complementary DNA strands (plasmid & foreign gene) at sticky ends in recombinant DNA technology.
to be an effective vector, plasmid must posses certain structures
selectable markers, regulatory sequences, origin of replication, restriction site.
selectable marker
selectable markers (antibiotic resistance) protect the micro-organism from selective agent (antibiotic) that would normally prevent it from growing. selectable marker genes ensure that only micro organisms that have taken up the vector grow in the presence of selective agent (antibiotic).
