Wednesday, December 29, 2010
Comparing Amino Acids & DNA
A quick review...
DNA provides instructions for the assembly of amino acids into protein.
Similar proteins have a similar amino acid sequence. And if the amino acid sequence is similar, the DNA is similar.
Scientists believe that similar DNA sequences indicate a common origin.
Hemoglobin (a protein in red blood cells) is one protein that has been studied in humans, gorillas, and horses.
Each group will be given 10 different colors of beads (each one representing a different amino acid - see list below).
Students use the beads to create the partial amino acid sequence for human, gorilla and horse hemoglobin (see below).
For assembly purposes, I give the students an index card with three pipe cleaners attached. It keeps it all in one place, and it makes it easy for the students to compare the sequences at the end.
After students have completed the amino acid sequences, I use my keys to quickly check their work.
From there, you can discuss...
--what determines the order of amino acids?
--where do we get our DNA from?
--where did our parents get their DNA from?
--random chnages in DNA occur over time, the mroe time passes, the more changes there will be.
At the end of the activity, students remove thier beads and return them to their appropriate bag.
The Amino Acid Sequences:
Human: gly lys val asp val asp glu val gly gly glu lys leu his val asp pro glu asp phe arg leu
Gorilla: gly lys val asp val asp glu val gly gly glu lys leu his val asp pro glu asp phe leu leu
Horse: asp lys val asp glu glu glu val gly gly glu lys leu his val asp pro glu asp phe arg leu
This activity comes from a wonderfully creative and talented teacher who presented it in a workshop at the New Jersey Science Teachers Association Convention. Unfortunately, I don't have her name written down. If you know her, or are her, please contact me and I will give her all the credit in the world for this great activity!