U2 Microorganisms Flashcards
Which of the 3 domains of life do microorganisms belong to?
All 3 domains
archaea
bacteria
eukaryotes
(around 50% of microbes are bacteria)
What do micro-organisms use and produce from their metabolic pathways?
use a wide variety of substrates for metabolism
produce a range of products from their metabolic pathways
Why are microorganisms widely used in research and industry?
They are easy to culture
They reproduce and grow quickly
Their metabolism can be controlled and manipulated relatively easily
What is growth media used for?
To supply microorganisms with raw materials (eg amino acids)
(many microorganisms produce all the complex molecules which they need (eg amino acids, vitamins and fatty acids) however, other microorganisms require these raw materials to be supplied via growth media.
As well as raw materials for making molecules, what else does growth media require?
An energy source
Where is an energy source for growth media , for making molecules, derived from?
either from chemical substrates (eg sugar) or from light in photosynthetic microorganisms
What is a fermenter used for?
To grow microbes on a large scale in order to get a useful product
Factors need to be controlled to ensure optimum yield of the product
Factors affecting growth of microbes?
sterility
temperature
oxygen levels
pH
Why are sterile conditions used in fermenters?
To reduce competition with desired microorganisms for nutrients and reduce the risk of spoilage of the product
How do we measure the growth in microbes?
by measuring the increase in cell numbers over a given period of time
phases of growth graph
x-time
y-number of cells (log)
lag phase (little/no growth-adjustment)
Log (exponential) phase-max rate of division
stationary phase-limiting factors and toxic builds up
death (decline) phase-death exceeds production
Lag phase
shows VERY LITTLE INCREASE IN CELL NUMBER as cells adjust to the conditions
microbes induce new enzymes to metabolise the substrate
Log phase
This is where the CELLS GROW AND MULTIPLY AT MAXIMUM RATE due to PLENTIFUL NUTRIENTS
Stationary phase
Takes place as the NUTRIENTS BEGIN TO RUN OUT (depleted) or toxic metabolites begin to accumulate
The NHMBER OF CELLS DYING IS EQUAL TO THE NUMBER OF NEW CELLS BEGING PRODUCED
Death phase
The final stage when the NUMBER OF CELLS DYING EXCEED THE NUMBER OF CELLS BEING PRODUCED
There is a LACK OF NUTRIENTS to support new cells or the accumulation of metabolites are so toxic that they can no longer survive
*stationary phase
What can be produced?
Secondary metabolites which are not needed for growth eg antibiotics
In the wild this gives the microbe an ecological advantage because it allows them to outcompete other microorganisms ie the antibiotic produced will kill other microbes
2 ways in which cell numbers can be counted
A TOTAL CELL COUNT involves all cells whether dead or alive
A VIABLE CELL COUNT involves counting only the cells which are alive
Which cell count shows a death phase where cell numbers are decreasing
viable cell counts
How can wild strains of microorganisms be improved?
By
-mutagenesis
-recombinant DNA technology
What is mutagenesis?
The creation of mutations.
Mutagens (eg exposure to UV light and other forms of radiation or mutagenic chemicals) results in mutations, some of which may produce an improved strain of microorganism
What does recombinant DNA technology enable genetic engineers to do?
To transfer gene sequences from one organism to another
What does recombinant DNA technology allow for?
The production of plant and animal protein by a microorganism that has been artificially transformed
Genetic engineers can find particular genes which code for desirable traits
This gene can then be inserted into a dna vector and then put into a bacterial cell
This bacterial cell then has the capabilities of the original gene
What is a vector?
A DNA molecule used to carry foreign genetic information into another cell
The bacterial plasmid which contains the desired gene is called a vector
contains the (desired gene), restriction site, origin of replication and marker gene
What are used as vectors?
Both plasmids and artificial chromosomes (are used as vectors during recombinant dna technology)
When are artificial chromosomes preferable to plasmids as vectors?
When larger fragments of foreign DNA are required to be inserted
What do restriction endonuclease enzymes do?
Cut target sequences of DNA
Different enzymes will target different seqences
Recombinant DNA technology-steps
1-A restriction enzyme is used to cut a target sequence of DNA
This will remove the required gene from the chromosome and will leave STICKY ENDS
2-The same restriction endonuclease enzymes cut open the restriction site on the plasmid leaving STICKY ENDS which are COMPLEMENTARY to those on the gene
3-LIGASE enzyme is used to SEAL PIECES OF DNA INTO PLASMIDS to make a recombinant plasmid with recombinant DNA. Altered plasmid can be inserted into host bacterial cell
Why are selective marker genes used for?
Allows cells with the plasmid to be easily identified
to protect the cells eg an antibiotic resistant gene
Cells subjected to the antibiotic and those with the vector will survive (while the others won’t survive)
As well as protection, what can another type of marker gene allow for?
Allows cells containing it to be easily identified eg a game which produces fluorescent proteins which show up under UV light
What does the origin of replication have!
genes responsible for the self-replication of the plasmid DNA (allows plasmid to make copies of itself)
It also has regulatory sequences allowing it to control the existing genes as well as the inserted genes (controls gene expression)
Recombinant DNA technology uses
insulin
human growth hormone
factor VIII
EPO
interferon
limitations of prokaryotes
eukaryotes like us contain lots of introns (non-coding regions of DNA)
Prokaryotes only contain exons
WHICH MEANS that a eukaryotic gene, when inserted into a prokaryote, may form an inactive protein as the POLYPEPTIDE MAY BE FOLDED INCORRECTLY
How do scientists overcome prokaryotes lack of introns?
They will often produce desired human proteins using genetically transformed yeast since yeast is a eukaryote
Next steps
To make sure the newly altered bacterium is safe to use in the environment, genes could be introduced that prevents its survival in the wild
