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

Knowledge of protein structure is preferred.

Learning Intentions

In this program student’s will:

• Learn how to compare protein profiles of different animals
• Experience setting up and running polyacrylamide gel electrophoresis
• Discover how proteomics is one method for determining evolutionary relatedness

Activities

Students will:

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

VCE links

• Evidence of relatedness between species: structural morphology – homologous and vestigial structures; and molecular homology – DNA and amino acid sequences
• The use and interpretation of phylogenetic trees as evidence for the relatedness between species

Learning Continuum

The following Learning Continuum is a guide for teachers to show the links between the programs Ecolinc offers onsite, online and through outreach. The Learning Continuum can be used to access Ecolinc resources to support the development of units of work.

Ecolinc Learn Online is an online learning management system offering interactive online courses for students and teachers. These courses can be undertaken either as a pre-visit, post-visit or stand-alone. Students are encouraged to do the pre-learning course before coming to Ecolinc for the onsite program.