Download Relationships and Biodiversity

Relationships and Biodiversity
This laboratory activity is a simulation that introduces the use of structural and molecular evidence for the
developing hypotheses about evolutionary relationships between several hypothetical plant species.
Students collect and analyze the data to determine which species is most closely related to a valuable but
endangered species (Botana curis).
What Did We Do and Why?
This lab sets up a hypothetical situation where scientists are looking for plants that may have an important
cancer fighting drug called Curol. The plant that produces Curol is small and endangered. So, your job
was to find possible alternative plants that may have the drug.
How can we do this, that is, to find a likely candidate?
Well, if you were to look for someone related to yourself you would more than likely look for someone
with similar physical characteristics. Likewise, if you wish to find a relative of the plant with Curol it
might be a good idea to find a plant with similar physical characteristics.
Part I
 You began by examining the leaves, stems, and seeds of each plant using a microscope. This data
was collected on a table chart.
Part II
 The second half of the experiment involves getting evidence for molecular similarities. You
examined the extract that was produced from the leaves by placing a drop on chromatography
paper. When the pigments separated as they went up the paper you could see which plants had the
same colors (protein pigments) as Botana curis. The plant(s) with the same pigments are more
likely to be related.
 The second molecular test involved searching for an enzyme called M. In this part you placed a
drop of the extract into a little dish and added an indicator that would cause bubbling if enzyme M
was present. Of course you know that enzymes are made of protein and therefore if two plants
have the same enzymes they are more closely related.
 The next phase of molecular testing involves examining the DNA of each plant. In this part of the
testing you were given different colored strips of paper with a genetic code in the form of a linear
sequence (ATCG…). At his time you were asked to cut each sequence at a particular location - on
each of the colored strands. This produces different sized fragments for each color. The scissors
represent Restriction Enzymes in real life. Remember restriction enzymes are used to cut DNA
sequences at specific locations. At his time you were asked to place the different size fragments on
the sheet of paper with boxes, which simulates Gel Electrophoresis. Please take a look at that page
in your lab now. (see the picture of the simulated electrophoresis on the next page.
(If you are not sure what it is you should take a moment to look it up on the net. You might wish
to find a simple video).

The next step in the lab is the comparison of the amino acid sequence. In this step you compared a
protein from each species of plant, looking for any differences in the amino acid sequence. The
more differences in the sequence the less related two species are. Why? The DNA holds the
instructions for building all protein parts of the organism
Relationships & Biodiversity
Testable Skills and Concepts

Use of structural (flowers, stems, seeds, etc.) and molecular (DNA, protein pigments, etc..)
similarities to determine evolutionary relationships.

Understanding of evolutionary trees and similarities due to common ancestry

The importance and maintenance of biodiversity

Construction of data tables incorporating qualitative and quantitative data

Use of a universal genetic code table

Use of a microscope to observe tissue organization

Use of chemical indicators

Use of chromatography to separate molecules

Use of gel electrophoresis for DNA fragments analysis

Use of safe laboratory practices when using chemicals