From Water to Land – Algae, Mosses and Ferns
In this practical in particular students make observations of a variety of different algae from the three main phyla – reds, browns and greens – as well as mosses and ferns. With mosses and ferns the focus is on a comparison of the lifecycles and dispersal mechanisms as well as overall morphology. The prac aims to reinforce concept presented in lectures (the evolution of land plants from green alga) by direct observation of features of the lower land plants that support this hypothesis.
Oxygen Consumption in Molluscs
This experiment is designed determine the influence of environmental temperature on the oxygen consumption of the Australian dog whelk, Dicathais orbita. Dicathais orbits is an intertidal mollusc found along most of the Australian coastline. Recently, it has been discovered that the ink released as a defence mechanism by this species contains a protein which functions as anticancer agent, causing apoptosis of cancerous cells. This finding has increased the medical and commercial interest of the species, and thus a desire to identify optimal conditions to facilitate the aquaculture of the species. Molluscs are ectothermic and conform the environment in which they live, therefore knowledge of the optimal temperature for growth and reproduction will be essential for successful commercial production of this species. The overall aim of the experiment is determine the temperature at which the rate of oxygen consumption is highest for Dicathais orbita, to ultimately apply this value to further development of aquaculture conditions for the species.
PCR amplification from student’s own DNA
The technique of Polymerase Chain Reaction (PCR) has revolutionised biology and biomedical science research and medical diagnosis and testing. PCR is applied in forensics to allow identification of individuals. This involves regions of the human genome that are highly variable, such as minisatellite loci. This experiment involves students purifying a sample of their own genomic DNA, and using PCR to amplify a specific minisatellite loci, D1S80. The PCR products are viewed by gel electrophoresis, and different alleles at minisatellite loci produce different length PCR products. Students analyse their own genotype and the results of some of their classmates, within the limitations of agarose gel electrophoresis.
Separating and Quantifying proteins
This experiment illustrates that molecules can be separated on the basis of their size (or hydrodynamic diameter) using the technique of column chromatography. The sample used, a mixture of bovine serum albumin (Mr 68,000) and a cobalt salt (Mr ~370) is passed through an inert solid matrix (Sephadex G25) through which flows a liquid phase (0.1M NaCl). Fractions of the eluate are collected as they flow out of the column and quantitatively analysed for protein using the Biuret method. This experiment is designed to be an effective learning tool to illustrate all the aims above. However anecdotal evidence from undergraduate students over the years suggests it may be too complicated for some level 2 students.
DNA Extraction from Strawberries
Ordinary household ingredients are used to extract DNA from strawberries. This experiment enables students to use their knowledge of cellular structure to explain concepts behind DNA extraction. This is a very crude extraction but an effective way to illustrate how DNA extraction works. This experiment can be taught at multiple levels from junior to senior high school or first year university. At the junior levels, students are able to see the DNA, by senior high or first year university they are expected to understand how the extraction is occurring. At the senior levels students can see how this crude extraction compares to how scientists extract DNA.
Proteins and Enzymes
Proteins are extremely important biological molecules, both structurally (e.g. your fingernails are made of the protein keratin, whilst collagen is a very important protein in connective tissue) and functionally as enzymes catalysing biological reactions. In part A of this prac, students determine the amount of protein in a sample, by effectively measuring the peptide bonds (as each amino acid has a peptide bond connecting it with the next) using a Biuret spectrophotometric assay. Students generate a standard curve, an extremely important tool in biochemistry.
Amylase Activity in Germinating Barley
In this experiment, students investigate and compare amylase activity in different life stages of barley. The experiment allows students to make connections between concepts and processes previously covered in lectures and reading materials and is relevant to learning and skills development in the scientific method and related areas such report writing and the interpretation of results. With regard to theoretical and conceptual knowledge, the practical investigates the function of an enzyme in a living organism and explores concepts around the ontogenic regulation of metabolism in an organism as it develops. Development of skills in the scientific method and the communication of science are also important components of this exercise.