Biotechnology
A cluster of practical activities for students to explore biotechnology involving viability of yeast, fruit juice production, milk products, fungal inhibition and microbial growth curves.
This cluster of practical activities was originally developed to support the Advanced Higher Biology specification from the Scottish Qualifications Authority.
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Converting Milk Products Using Lactase
The enzyme lactase is widely used in the dairy industry to convert the naturally occurring disaccharide sugar lactose into glucose and galactose. In this practical students investigate the treatment of milk with lactase. Following treatment they test the glucose content of the converted milk, and compare products of frozen converted…
Determining Doubling Time
As the number of cells in a microbial culture increases, turbidity increases. In this experiment students calculate doubling time and growth rate constant using absorbance as the measure of growth. Turbidity is caused by suspended cells in the growth medium scattering light, and may be measured using a colorimeter. Absorbance…
Determining Dry Weight
This experiment is a continuation of Determining Doubling Time. Students create a standard curve of absorbance against yeast concentration, and use this to determine the concentration of yeast produced over time. The standard curve (dry mass, grams per litre) is generated from known concentrations of dried yeast in sterile broth.…
Fruit Juice Production
Fruit juice companies use a variety of different treatments and enzymes to maximise their yield. In this experiment students will investigate the effectiveness of these different enzymes. The enzymes used are designed to break down cells walls and release the liquids and sugars which make up the fruit. Pectinases, amylases and…
Fungal Inhibition
In this experiment students grow yeast on agar plates and look at the effect on growth of some common anti-fungal treatments, which are available to treat conditions such athlete's foot and thrush. Antifungal products may be bought from a local pharmacist, for example, Canistan, Daktarin, Diflucan. Several different yeast…
Testing the Viability of Yeast
Several different treatments are used to autolyse yeast cells. The viability of the autolysed yeast is then tested by: plating out on agar; testing for dehydrogenase activity; microscopic examination with methylene blue. Background In the food industry, yeast is grown in huge fermenters and then given different treatments to…
Upgrading Whey
Whey is a waste product from the cheese industry. In this experiment students upgrade whey, by converting the lactose into glucose and galactose, or by growing the microorganism K.lactis on agar containing whey. Cheese companies are currently developing ways of upgrading the whey so that they can increase their profits and reduce…
Collection author
Resource by: Science & Plants for Schools (SAPS)
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