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Specification
· (a) state that biotechnology is the industrial use of living organisms (or parts
of living organisms) to produce food, drugs or other products (HSW6a);
· (b) explain why microorganisms are often used in biotechnological
processes;
· (c) describe, with the aid of diagrams, and explain the standard growth
curve of a microorganism in a closed culture;
· (d) describe how enzymes can be immobilised;
· (e) explain why immobilised enzymes are used in large-scale production;
· (f) compare and contrast the processes of continuous culture and batch
culture;
· (g) describe the differences between primary and secondary metabolites;
· (h) explain the importance of manipulating the growing conditions in a
fermentation vessel in order to maximise the yield of product required;
· (i) explain the importance of asepsis in the manipulation of microorganisms.…read more

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Biotechnology
What is Why use biotechnology?
biotechnology? · Ideal growth conditions can be easily
created
The industrial use of
· They grow rapidly so products can be
living organisms to made quickly
produce food, drugs · Grow on a range of inexpensive (even
and other products. waste) materials
Microorganisms are · Can be grown at any time of the year
mainly used. Can · Isolated enzymes, that aren't
also use parts of contained in cells, can be immobilised
· Produce asexually so genetically
organisms (e.g., identical
enzymes) to make · Only a single copy of each gene so no
products. gene masking occurs (bacteria)…read more

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growth curve of a microorganism
in a closed culture
Lag phase= Pop'n size increases slowly
because the microorganisms
need to make enzymes and other
molecules before they can
reproduce
Log phase= pop'n size increases rapidly
because there are the most
favourable conditions (lots of food, not
much competition)
Stationary phase= pop'n size stays level
because reproduction rate=
death rate because not enough
food and build up of toxic waste
products
Death phase= pop'n size decreases
rapidly due to scarcity of food and
high levels of toxic waste…read more

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Immobilising enzymes
How?
1. Adsorption- enzymes are mixed with an immobilising support (e.g., porous carbon
and glass beads)and bind to it by hydrophobic interactions and ionic links. Gives
high reaction rates however, can leak due to weak bonding forces
2. Can be covalently bonded to cellulose or collagen fibred, very little leakage but only
binds a small amount of enzyme
3. Entrapment- enzymes can be trapped in a silica gel matrix. Reduced rate due to
substrate molecules needing to get through barrier
4. Mb separation- enzymes can be separated with a partially permeable mb.
W Advantages disadvantages
Enzymes aren't present with product so Requires additional time, equipment
H low purification costs and material so, expensive to set up
Y Enzymes immediately available for reuse- May be less active because don't
? allows a continuous process freely mix with substrate
More stable because immobilising matrix Any contamination is costly as
protects the enzyme molecules requires whole system to be stopped…read more

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cultures
Batch culture- microorganisms are grown in Continuous culture- microorganisms are
individual batches in a fermentation vessel, continually grown in a fermentation vessel
when one culture ends, it is removed and a without stopping
different batch is then grown
A fixed vol of growth medium is added to the Growth medium flows through vessel at a steady
vessel at the start of the culture, then no more is rate. It's an open system
added. It's a closed system
Each culture goes through lag, exponential and The culture goes through lag phase but is kept at
stationary growth phases the exponential growth phase
Product is harvested once, during stationary phase Product is continually harvested and
microorganisms are growing exponentially
Product yield is low- vessel needs to be steralised Product yield is high due to microrganisms
between fermentation so no product is harvested constantly growing at an exponential rate
at these times
If one batch is contaminated, it is easy to discard If the culture is contaminated it all needs to be
and start a new one discarded- this is expensive on an industrial scale
Used to produce secondary metabolites Used when you want primary metabolites or the
microorganism themselves…read more

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