Mutations:

Mutations are changes in the sequence of DNA. These changes could be a single base change or an insertion/deletion of a entire segment of the DNA. Mutations, if occurring within the coding regions of genes, can change the structure of the gene and thus affect the structure of the protein produced by the gene.

A good description of mutations can be found at: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mutations.html.

Activity:

We are going to examine the effects of mutations on protein sequence by using the beta-globin gene. This gene codes for the beta subunit of hemoglobin. Hemoglobin is responsible for binding oxygen in the blood. One type of mutation that can occur in bets-globin is demonstrated by the two sequences below. 
 

Sickle cells Anemia Genetics:

http://imiloa.wcc.hawaii.edu/krupp/BIOL101/present/lcture17/img022.jpg

NORMAL mvhltpeeks avtalwgkvn vdevggealg rllvvypwtq 
SICKLE mvhltpveks avtaxwgkvn vdevggealg rllvvypwtq
 
 
rffesfgdls tpdavmgnpk vkahgkkvlg afsdglahld 
rffesfgdls tpdavmgnpk vkahgkkvlg afsdglahld
 
 
nlkgtfatls elhcdklhvd penfrllgnv lvcvlahhfg
nlkgtfatls elhcdklhvd penfrllgnv lvcvlahhfg
 
 
 
keftppvqaa yqkvvagvan alahkyh
keftppvqaa yqkvvagvan alahkyh
 

As you can see, these two sequences are identical except for the 7^th amino acid; a change from glutamic acid (e) to valine (v) occurs. When this change occurs, it affects the structure of the beta-globin protein and the function of the hemoglobin protein. In fact, the shape of the red blood cell is also changed.

http://www.blc.arizona.edu/courses/181gh/rick/human_genetics/jpegs/cells.jpg

A good description of the sickle cell disease and the effect of the mutations can be found at:

How Does Sickle Cell Cause Disease?

I have devised a game that can be played to reinforce the concept of mutational changes and their effect on protein structure. This game is based upon the sickle cell model.

Material:

o Poster board

o Construction paper to print out amino acids

o Template for amino acids-

o Self-adhesive Velcro strips

Game details:

There are thirteen amino acids for each molecule. Divide the students into two research teams; the team working with the normal beta-globin protein and the team working with the abnormal beta-globin protein. Hand out one amino acid to each student on the teams. The team studying the normal protein, who get the green amino acids, have the sequence for the normal protein. These students will place their amino acid in the correct order (the number printed in red on the back of the cards give the order). This research team has sequenced the normal protein.

The research team studying the abnormal beta-globin will then reveal their sequence by aligning the sequences. All but one amino acid will line up! The objective is for this team to determine which one is different and thus where the mutation has occurred.