Repository of biology practicals

Students are not provided with a protocol, but instead work in groups to design their own set of experiments to investigate a classic clock reaction and to control the time when colour appears. They receive some marks for how close they can get to random times in observed trials. The students are guided in their design, but are not directly told how to achieve their aims, and in fact several different strategies are possible.

Material of tobacco seedlings grown aseptically is used to test to observe in vitro regeneration and to test to impact of concentrations of different hormones, including one which visualises the difference between transportable and untransportable auxin.

The huge diversity, yet essential commonality, of flowers is demonstrated by examining three very different monocot flowers, one of which can be easily cultivated, the other two obtained from florists. The genes underlying development, and therefore potential evolutionary change, is visualised through examination of Arabidopsis floral homeotic mutants, obtained from a stock centre.

These are three practicals which can be carried out together as one or independently. It focuses on chloroplast biology and uses Arabidopsis. It visualises (1) a genetic defect (arc6 mutant) in chloroplast division and (2) a change in a nuclear reporter gene expression (pLHCB::GUS) when chloroplast translation is inhibited. Lastly (3), a bioinformatic exercise asks students to explore the origin, from cyanobacteria, through endosymbiosis, of a higher plant chloroplast division gene, ARC6.

Polyphenol oxidase (PPO) enzyme is of great commercial interest because it is related to the browning of fruits. In this practical spanning two weeks, we will use classical biochemical techniques to extract a PPO enzyme from a banana or apple, perform an assay for PPO activity and protein content, and assess data to discuss reproducibility in science.

We will discuss the roles that environmental sensors, such as the phytochromes and cryptochromes, play in the onset of flowering. We will use molecular genetic techniques to detect mutations and discuss how this approach can assist in unravelling biological problems.