Name: ________________________

BIO300/CMPSC300

Mutation - Spring 2016

As you know from lecture, 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.

POINT MUTATION (one base is substituted for another)

If a point mutation changes the amino acid, it’s called a MISSENSE mutation.

If a point mutation does not change the amino acid, it’s called a SILENT mutation.

If a point mutation 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: A U G U G G A A C C G C U G C U G A

Amino Acid Sequence: MET -TRP- ASN - ARG- CYS - (STOP)

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? A U G U A G A A C C G C U G C U G A

What will be the amino acid sequence? MET -(STOP)

Will there likely be effects? YES What kind of mutation is this? POINT MUTATION- NONSENSE

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? A U G C U G G A A C C G C U G C U G A

What will be the amino acid sequence? MET - LEU -GLU– PRO-LEU-LEU

Will there likely be effects? YES What kind of mutation is this? INSERTION - FRAME SHIFT

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? A U G U G G A A U C G C U G C U G A

What will be the amino acid sequence? MET-TRP-ASN- ARG- CYS (STOP)

Will there likely be effects? NO What kind of mutation is this? POINT MUTATION– SILENT

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? A U G U G G A A C C G C U G A U G A (Circle the change)

What will be the amino acid sequence? MET-TRP- ASN- ARG- (STOP)

Will there likely be effects? YES What kind of mutation is this? POINT MUTATION – NONSENSE

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Name: ________________________ BIO300/CMPSC Mutation - Spring 2016 As you know from lecture, 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. POINT MUTATION (one base is substituted for another) If a point mutation changes the amino acid, it’s called a MISSENSE mutation. If a point mutation does not change the amino acid, it’s called a SILENT mutation. If a point mutation 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: A U G U G G A A C C G C U G C U G A Amino Acid Sequence: MET - TRP- ASN - ARG- CYS - (STOP) 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? A U G U A G A A C C G C U G C U G A What will be the amino acid sequence? MET - (STOP) Will there likely be effects? YES What kind of mutation is this? POINT MUTATION- NONSENSE 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? A U G C U G G A A C C G C U G C U G A What will be the amino acid sequence? MET - LEU - GLU– PRO-LEU-LEU Will there likely be effects? YES What kind of mutation is this? INSERTION - FRAME SHIFT 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? A U G U G G A A U C G C U G C U G A What will be the amino acid sequence? MET-TRP-ASN- ARG- CYS (STOP) Will there likely be effects? NO What kind of mutation is this? POINT MUTATION– SILENT 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? A U G U G G A A C C G C U G A U G A (Circle the change) What will be the amino acid sequence? MET-TRP- ASN- ARG- (STOP) Will there likely be effects? YES What kind of mutation is this? POINT MUTATION – NONSENSE

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? A U G U G G A A C C C U G C U G A What will be the amino acid sequence? METHIONINE-TRYPTOPHAN-ASPARAGINE- PROLINE - ALANINE Will there likely be effects? YES What kind of mutation is this? DELETION – FRAME SHIFT

Which type of mutation can cause new variations of a protein? FRAME SHIFT AND MISSENSE
Which type of mutation results in abnormal amino acid sequence? FRAME SHIFT, NONSENSE, AND MISSENSE
Which type of mutation stops the translation of the mRNA? NONSENSE Review Questions
A genetics found that a particular mutation had no effect on the protein coded for by the gene What do you think the is the most likely type of mutation in this gene? Why?
Name one amino acid that has more than one codon. Name one amino acid that has only one codon.
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?
Two of the following three RNA sequences code for the same protein – which two? #1 AGU UUA GCA ACG AGA UCA #2 UCG CUA GCG ACC AGU UCA #3 AGC CUC GCC ACU CGU AGU How many point mutations are there between the two sequences?

DNA Mutation Worksheet Key - Bioinformatics, Exercises of Bioinformatics

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A U G U G G A A C C G C U G C U G A

METHIONINE-TRYPTOPHAN-ASPARAGINE-ARGININE-CYSTEINE- (STOP)

Point mutation – silent mutation.

If there was no effect on the protein coded by the gene, then the amino acid sequence must have

been the same as the original sequence. Therefore the mutation must have been a point mutation

resulting in a codon that encoded the same amino acid as the original amino acid.

Methionine and Tryptophan have only one codon. All other amino acids have more than one codon.

TEF ATC ATE TET HER AT

This sentence no longer makes sense. This is an example of a deletion resulting in a frame shift.

# 1 and # 3 have the same amino

acid sequence, therefore they code

for the same protein

10 point mutations