Download Mutations Worksheet

Name: __________________________________________ Date: ________________________ Period: ______
MUTATIONS PRACTICE SHEET
There are several types of mutation:
DELETION (a base is lost)
INSERTION (an extra base is inserted)
Deletion and insertion may cause what’s called a FRAMESHIFT, meaning the reading “frame”
changes, changing the amino acid sequence.
SUBSTITUTION (one base is substituted for another)
If a substitution changes the amino acid, it’s called a MISSENSE mutation.
If a substitution does not change the amino acid, it’s called a SILENT mutation.
If a substitution changes the amino acid to a “stop,” it’s called a NONSENSE mutation.
Complete the boxes below. Classify each as either Deletion, Insertion, or Substitution AND as either
frameshift, missense, silent or nonsense (hint: deletion or insertion will always be frameshift).
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?
Will there likely be effects?
Mutated DNA Sequence #2:
What kind of mutation is this?
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?
Will there likely be effects?
Mutated DNA Sequence #3:
What kind of mutation is this?
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?
Will there likely be effects?
Mutated DNA Sequence #4:
What kind of mutation is this?
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?
Will there likely be effects?
What kind of mutation is this?
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 #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?
Will there likely be effects?
What kind of mutation is this?
1. Which type of mutation is responsible for new variations of a trait?
2. Which type of mutation results in abnormal amino acid sequence?
3. Which type of mutation stops the translation of the mRNA? ______________________________________________
Sickle Cell Anemia
Sickel cell anemia is the result of a type of mutation in the gene that codes for part of the hemoglobin molecule. Recall
that hemoglobin carries oxygen in your red bloods cells. The mutation causes the red blood cells to become stiff and
sickle-shaped when they release their oxygen. The sickled cells tend to get stuck in blood vessels, causing pain and
increased risk of stroke, blindness, damage to the heart and lungs, and other conditions.
Analyze the DNA strands below to determine what amino acid is changed and what type of mutation occurred.
Normal hemoglobin DNA
CACGTGGACTGAGGACTCCTC
Normal hemoglobin mRNA
Normal hemoglobin AA sequence
--------------------------------------------------------------------------------------------------------------------------------
Sickle cell hemoglobin DNA
Sickle cell hemoglobin mRNA
Sickle cell hemoglobin
CACGTGGACTGAGGACACCTC
CONCLUSIONS
1. Which type of mutation is responsible for new variations (alleles) of a trait?
2. Which type of mutation results in abnormal amino acid sequence?
3. Which type of mutation stops the translation of the mRNA?
2. A geneticist found that a particular mutation had no effect on the protein coded by a gene. What do you
think is the most likely type of mutation in this gene? Why?
4. Examine your genetic code chart. Name one amino acid that has more than one codon. Name an amino acid
that has only one codon.
5. Look at the following sequence: THE FAT CAT ATE THE RAT. Delete the first H and regroup the letters in
groups of three- write out the new groups of three. Does the sentence still make sense? What type of
mutation is this an example of?
6. Given the following three mRNA sequences, determine which two code for the same protein. Circle them.
Transcript
mRNA #1
mRNA #2
mRNA #3
AGU UUA GCA ACG AGA UCA
UCG CUA GCG ACC AGU UCA
AGC CUC GCC ACU CGU AGU
Translate
BONUS: You have a DNA sequence that codes for a protein and is 105 nucleotides long. A frameshift mutation
occurs at the 85th base - how many amino acids will be correct in this protein? SHOW YOUR WORK.
A Little Review…
Label the following diagram. Be sure to use each of the words listed
Transcription, translation, tRNA, mRNA, DNA, Amino Acid, polypeptide chain, codon, anticodon, ribosome,
nucleus, cytoplasm
9.
11.
10.
12.
Diagnostic Question:
The statement “DNA goes to RNA goes to protein” is used as a shorthand description of the flow of information
in the cell. a) “DNA goes to RNA” is meant to describe the process of _______________________. For this
process to occur, we need an enzyme called _____________________ that uses DNA as a template to make
_________________________. b) “RNA goes to protein” is meant to describe the process of
_______________________. Three different types of RNA are used in this process. _________________ RNA
is used as the template to make a _____________________. ___________RNA is part of the complex called a
______________ required for protein synthesis. __________RNA is a small RNA molecule that acts as an
adapter between RNA and protein.
Critical Writing:
In the space provided describe the process of protein synthesis in GREAT detail following the Central Dogma of life:
DNA – RNA – Protein. Some things to think about when writing:
1. How is DNA opened and copied by RNA? How does mRNA make the copy?
2. How does mRNA get to the cytoplasm?
3. Where do the nucleotides come from? Where do the amino acids come from?
4. What is the codon/anticodon?
5. Role of the ribosome? Etc…….