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Flashcards in B: Microorganisms in Industry Deck (37):

Who discovered penicillin. When did they discover it? How did they discover it? What is this called in biology?

- Alexander Flemming
- 1920s

by chance:
- Petri dish growing bacteria
- bacteria contaminated with Penicillium
- bacterial colonies near fungus died out
- Fleming realised chemical produced by fungus was acting as a biocide

chance discovery is called 'serendipity'


When was a method for mass-producing penicillin developed? What was the method called?

- 1940s
called deep-tank fermentation


What is an obligate aerobe?

an organism that requires oxygen to grow


Penicillium is an obligate aerobe. What is the significance of this when growing Penicillium?

oxygen must be bubbled through the fermenter, with paddles to distribute it evenly
(otherwise it will die)


What are the optimum conditions for Penicillium? What is the nutrient source for Penicillium?

- oxygen must be present
- 24°C
- slightly alkaline pH

- corn steep liquor


When is penicillin produced by Penicillium? What do we call this kind of production? What type of fermentation, therefore, is used to produce penicillin?

- only produced if nutrient concentrations are low
- secondary metabolite (organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism)
- batch culture


What can be said of initial nutrient concentrations when mass-producing penicillin? Why are they like this?

- nutrient concentrations are high
- to stimulate the fungus to grow


What has happened after about 30 hours since the start of the batch culture production of penicillin? What is the effect of this event? Why does this happen?

- nutrient concentrations have dropped
- penicillin production starts and continues for about 6 days
- penicillin is produced by Penicillium when nutrient concentrations are low


When is the batch culture production of penicillin fermenter drained? What happens after drainage?

- 6 days after the process began
- liquid from fermenter filtered and then solvents are used to precipitate the penicillin


What is citric acid? How is it used?

- it is a food additive
- used as a flavour enhancer and preservative


What does industrial production of citric acid rely on?

the fungus - Aspergillus niger


How is most citric acid industrially produced? Can it be produced any other way?

- mostly batch fermentation
- sometimes continuous fermentation


What are the optimal conditions for the industrial production of citric acid?

- high dissolved oxygen
- sugar concentrations
- acidic pH
- 30°C


Citric acid is produced in a cell cycle. What would we therefore call citric acid? Which cell cycle is citric acid produced in?

- primary metabolite
- Krebs cycle


Under what conditions does citric acid build up?

if culture is undersupplied with minerals such as iron


In continuous fermentation, how can citric acid be harvested?

by draining off fluid, filtering, then precipitating citric acid by adding calcium hydroxide


Define 'proteome'.

the complete set of proteins that it can produce


What does the proteome depend on?

the genes that are in the genome


How can the proteome be altered?

by genetic engineering - a new gene is added to the genome, which is expressed to produce a protein not previously in the proteome


When is an organism said to be 'transgenic'?

if it has been genetically modified with a gene from another organism


Through genetic engineering, a gene can be added to the genome, which is expressed to produce a protein not previously in the proteome. What is this new gene called?

the target gene


What must the target gene do if the transgenic organism is to be useful?

target gene must be expressed at an appropriate rate when required and not at other times


How is appropriate expression of the target gene achieved?

by linking it to other base sequences that control its expression


What are marker genes? Give an example.

- genes that are linked up to the target gene to indicate whether the target gene has been uptaken successfully by the intended transgenic organism
- marker gene example: gene for antibiotic resistance - cells that have not successfully uptaken target gene will be killed when treated with the antibiotic


What makes it relatively easy to find target genes in other species?



What is biogas?

the combustible gas produced in a fermenter by the anaerobic breakdown of organic matter


Name 3 sources of biogas.

manure, waste plant matter from crops and household organic waste


What is biogas mostly comprised of? What does this depend on?

- methane with some carbon dioxide
- the construction of the fermenter


Outline the series of processes carried out by the different bacteria in a biogas generator.

1) conversion of raw organic waste into organic acids, alcohol, hydrogen, and CO2
2) conversion of organic acids and alcohol to ethanoic acid, carbon dioxide and hydrogen
3) production of methane by reducing CO2 with hydrogen or splitting ethanoic acid


What are methanogens?

bacteria that produce methane


Draw a diagram of a simple biogas generator (p159)

1. mylar balloon (basically helium party balloons)
2. glass connector tubes
3. tube clamps
4. rubber tube
5. plastic feedstock bottle (not glass to minimise risk of explosion)


What is a reading frame?

a sequence of consecutive, non-overlapping codons in DNA or RNA


How many possible reading frames are there in any piece of DNA or RNA? What



What determines which reading frame should be used on a piece of DNA or RNA?

the start codon


What is an ORF?

open reading frame


What is an open reading frame?

a length of DNA from a start codon to a stop codon that is long enough to code for a polypeptide


How many triplets of nucleotides (codons) are usually expected in an ORF?

100+ triplets

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