Name
March 22, 2012
Class: C1
C2
Mutations Worksheet
During replication, transcription and translation there can be a mistake made in the bonding of complementary
bases. These mistakes will lead to mutations. There are three main types of mutations: point mutations,
insertion, and deletion mutations (the latter two are both frameshift mutations). In each of the following DNA
sequences, you will use the mRNA and amino acid sequences to identify the mutation that occurred. Amino
acid chains will become proteins. Remember back to the function of enzymes, which are proteins, and how a
change in the shape of proteins will change their ability to work. Now add to this thought, changing the
sequence of amino acids in a chain can change how the protein is folded and shaped, therefore changing its
function. Use these sections of DNA to see what impact on the amino acid sequence is achieved by the
different mutations! 10 points
Original DNA Sequence:
T A C A C C T T G G C G A C G A C T
mRNA Sequence:
Amino Acid Sequence:
Mutated DNA Sequence #1: T A C A T C T T G G C G A C G A C T
What’s the mRNA sequence?
(Circle the change)
What will be the amino acid sequence?
How many amino acids are different? ________ What kind of mutation is this?
Mutated DNA Sequence #2: T A C G A C C T T G G C G A C G A C T
What’s the mRNA sequence?
(Circle the change)
What will be the amino acid sequence?
How many amino acids are different? ________
What kind of mutation is this?
Mutated DNA Sequence #3: T A C A C C T T A G C G A C G A C T
What’s the mRNA sequence?
(Circle the change)
What will be the amino acid sequence?
How many amino acids are different? ________
What kind of mutation is this?
Mutated DNA Sequence #4: T A C A C C T T G G C G A C T A C T
What’s the mRNA sequence?
(Circle the change)
What will be the amino acid sequence?
How many amino acids are different? ________
What kind of mutation is this?
Mutated DNA Sequence #5: T A C A C C T T G G G A C G A C T
What will be the corresponding mRNA sequence?
What will be the amino acid sequence?
How many amino acids are different? ________
What kind of mutation is this?
Discussion Questions: (you may use your table partners)
1. If mutated DNA Sequence #1 occurred in a single cell on the membrane of a fish, how might it impact
the organism?
2. If mutated DNA Sequence #1 occurred in a single reproductive cell of a fish that was later fertilized to
become an offspring, how might it impact the organism?
3. If mutated DNA Sequence #2 occurred in a reproductive cell of a fish that was later fertilized to become
an organism. And the mutation occurred in a gene that coded for a hormone needed for growth, how
might it impact the organism?
4. If mutated DNA Sequence #1 occurred in a reproductive cell of a fish that was later fertilized to become
an organism. And the mutation occurred in a gene that coded for a pigment that normally appears blue
and as a result of the mutation appears red, how might it impact the organism?
5. DNA replication, transcription, and translation all have enzymes whose job it is to attach the
complementary nucleotides to an existing strand. Nonetheless, these enzymes do make mistakes at a
rate of about 1 per every 100,000 nucleotides. That might not seem like much, until you consider how
much DNA a cell has. In humans, with our 6 billion base pairs in each diploid cell, that would amount to
how many mistakes?
6. In order to reduce the number of mutations drastically organisms have enzymes that proofread new
strands of DNA and RNA and fix mutations. Mutation rates vary depending on species from mutation
rates as low as 1 mistake per 100 million to 1 billion nucleotides, mostly in bacteria, and as high as 1
mistake per 100 to 1,000 nucleotides, the latter in a group of error-prone polymerase genes in humans.
Even low mutation rates can accumulate over time. What might be an positive effect of mutations (think
about question 4)?