Name _______________________________________
Section 8.7: Mutations
Date __________________
Main Ideas:
 Some mutations affect a single gene, while others affect an entire chromosome
 Mutations may or may not affect phenotype
 Mutations can be caused by several factors
Vocabulary:
 Mutation
 Point mutation


Frameshift mutation
Mutagen
1. Define the term mutation.
2. During what process involving DNA would a single gene mutation occur? ______________________
3. When would a mutation involving many genes or the entire chromosome occur? _________________
Look at the following sentence. Consider it a gene on DNA. THE FAT CAT ATE THE RAT. Remember
that we always read DNA and mRNA in words of three. Always keep your codons in words of three.
4. I would like you know to change the C on CAT to a B. THE FAT _____ ATE THE RAT. Has the rat
still been eaten by a fat animal? Did it drastically change the meaning of the sentence? _______.
5. Now change the C to a K. THE FAT ___ ATE THE RAT. Did it drastically change the meaning? __
6. Try this one. Take out the F in FAT. THE _____ ______ _____ _____ ____. Did this deletion of the
F drastically change the meaning of the sentence? ________________. Does it make sense? ________
You have looked at three examples of gene mutations, one more serious than the other.
7. #4 and # 5 were point mutations. Explain what a point mutation is.
Example #5 is a silent point mutation because it doesn’t change the meaning of the sentence/gene at all. No one
would ever know that there was a change.
8. #7 was a frameshift mutation. Explain what a frameshift mutation is.
Example #7 is a nonsense frameshift mutation because the statement/protein has totally been change.
9. Look at Figure 8.2. Explain which mutation would have the greatest effect and why.
10. The diagram below is showing you a portion of the normal red blood cell hemoglobin gene and then the
mutated sickled red blood cell hemoglobin gene and what the cells will look like for each. What do you
see is the difference between the normal red blood cell DNA and the sickled red blood cell DNA?
11. Would the person with this mutation pass it on to their offspring (if they lived long enough to
reproduce)?_______________________________
12. Example the diagram below showing you how chromosomal mutations occur. During what process
do chromosomal mutations occur? _________________ What happened to the number of chromosomes
in the gametes during this process (remember that meiosis reduces the number of chromosomes in our
gametes/sex cells in half so in this diagram, the normal number of chromosomes following meiosis in
each gamete should be 2). ___________________________________________________________.
Examine the karyotype to the right. Notice that there are 3 #21 chromosomes. What is this called?
________________________.
13. What is a mutagen?
14. Please name three known mutagens. ______________ ________________ _______________