Background

Changes in proteins can reflect changes in the gene pool of organisms. Muscle consists mainly of actin and myosin proteins, which are essential for movement and survival in animals. These proteins have remained relatively unchanged in animals over time, however there are other muscle proteins that show considerable variation even between closely related species. The variations between organisms’ protein profiles reflect physiological adaptations to different environments, which have originated as random DNA mutations. If favorable, these mutations will persist through the natural selection process and contribute to the evolution of the species.

Evolutionary or phylogenetic trees can be based on many different types of data. Some are constructed using a single type of data and others use multiple types of data. Today, similarities and differences in protein and DNA sequences are being used and may include the morphology of both living organisms and fossils. Not all methods used to construct evolutionary trees will always agree as some shared characteristics between organisms may be similar in structure and function but have evolved independently.

A family tree, or cladogram, can be constructed based on protein bands that the animals have in common formed on polyacrylamide gels. The analysis of the protein bands assumes that when two organisms share a common characteristic, they also share a common ancestor with that same characteristic.

Prior Knowledge

No prior knowledge required.

Learning Intentions

In this program student’s will:

• learn how to compare protein profiles of different animals
• set up and run polyacrylamide gel electrophoresis
• discover how proteomics is one method for determining evolutionary relatedness

Activities

• Predict evolutionary relatedness of several marine animals given species data
• Extract protein from muscle tissue
• Run polyacrylamide gel electrophoresis
• Analyse gels
• Construct a cladogram showing evolutionary relatedness of marine animals

VCE links

• Outcome 1 SAC - Analyse evidence for evolutionary change, explain how relatedness between species is determined, and elaborate on the consequences of biological change in human evolution.