Biotechnology and Genetic Engineering.

Biotechnology uses microorganisms such as bacteria and fungi. Also uses enzymes.

Immobilised Enzymes.

Can be immobilised in many ways:

Encapsulated in alginate beads.

Trapped in silica gel matrix.

*Covalently bonded to cellulose or collagen fibres.

Substrate solution is passed through a column of immobilised enzymes.

Advantages:

*Immobilised  enzymes can be reused.

*the product is not mixed with enzymes.

*Immobilised enzymes are more stable, less likely to denature.

Standard Growth Curve.

1. Lag Phase. A slow increase, enzymes etc. are made.

2. Exponential Phase. Faster increase, favourable conditions.

3. Stationary Phase. Death rate equals reproduction rate.

4. Decline Phase. Food becomes scarce and waste reaches toxic levels.

Fermentation Vessels.

*pH and temperature kept at optimum for efficiency.

*Sterilised between uses with steam, so microorganisms are not competing.

*Microorganisms kept in contact with fresh medium by circulation with paddles, so they can always access nutrients.

*Oxygen is kept at optimum for respiration.

Batch Culture.

Fixed volume of medium added at start.

Stops at stationary phase.

Harvested once at the end.

Low yield, period where nothing happens.

Contamination only affects one batch.

Secondary metabolites produced.

Continuous Culture.

Medium flows at steady rate.

Kept at exponential phase.

Continuously harvested.

Higher yield.

Contamination means all is discarded.

Primary metabolites or microorganisms themselves are produced.

Asepsis.

Preventing contamination, eg. sterilising equipment, and lids being suspended over containers rather than placed on surfaces.

Gene Technologies.

Polymerase Chain Reaction (PCR).

Used to make millions of copies of a fragment of DNA.

*Reaction mixture contains DNA sample, free nucelotides, primers (short pieces of DNA complementary to sample.) and DNA polymerase.

*Heated to 95 degrees to break hydrogen bonds in DNA. Cooled to 50 degrees where the primers bind.

*heated to 72 degrees so DNA polymerase lines up nucleotides and makes complementary strands.

*Two new copies formed. Starts again with 4 strands as templates.

Restriction Enzymes.

Recognise palindromic sequences and digest at them.

If…