Download Biology Honors Mutations Worksheet Key and more Exercises Biology in PDF only on Docsity!
Delahunty/Biology Honors Mutations Worksheet Name KEY
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: A U G U G G A A C C G C U G C U G A
Amino Acid Sequence: METHIONINE -TRYPTOPHAN - ASPARAGINE - ARGININE- CYSTEINE - (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 (Circle the change)
What will be the amino acid sequence? METHIONINE -(STOP)
Will there likely be effects? YES What kind of mutation is this? SUBSTITUTION
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 (Circle the change)
What will be the amino acid sequence? METHIONINE - LEUCINE -GLUTAMIC ACID – PROLINE
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 (Circle the change)
What will be the amino acid sequence? METHIONINE-TRYPTOPHAN-ASPARAGINE- ARGININE- (STOP)
Will there likely be effects? NO What kind of mutation is this? SUBSTITUTION
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? METHIONINE-TRYPTOPHAN-ASPARAGINE- (STOP)
Will there likely be effects? YES What kind of mutation is this? SUBSITUTION - NONSENSE
Analyze the DNA strands below to determine what amino acid is changed and what type of mutation occurred.
Normal hemoglobin DNA C A C G T G G A C T G A G G A C T C C T C
Normal hemoglobin
mRNA g u g c a c c u g a c u c c u g a g g a g
Normal hemoglobin A.A. sequence VALINE-HISTIDINE-LEUCINE-THREONINE-PROLINE- GLUTAMIC ACID-GLUTAMIC ACID
Sickle cell hemoglobin DNA C A C G T G G A C T G A G G A C A C C T C
Sickle cell hemoglobin mRNA G U G C A C C U G A C U C C U G U G G A G
Sickle cell hemoglobin A.A. sequence VALINE-HISTIDINE-LEUCINE-THREONINE-PROLINE- VALINE-GLUTAMIC ACID
http://staff.fcps.net/einman/biology/MutationsWS.doc
TEF ATC ATE TET HER AT
This sentence no longer makes sense. This is an example of a deletion resulting in a frame shift.
Methionine and Tryptophan have only one codon. All other amino acids have more than one codon.
Substitution – 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 substitution resulting in a codon that encoded the same amino acid as the original amino acid.
Chromosomal mutations change the structure of a chromosome
o deletions – part of chromosome is lost o duplication – part of chromosome is copied o inversion – part of chromosome in reverse order
translocation – part of chromosome is moved to a new location
o o - triplet repeat expansion mutations involve a sequence of 3 DNA nucleotides that are repeated many times
Point mutations - alter a single base
o base substitution mutations – substitute one base for another o nonsense mutations – create stop codon o frameshift mutations – caused by insertion or deletion of a single base
A frame shift mutation results from an insertion or a deletion, alters the sequence of bases in codons at the mutation and after the mutation. This changes the amino acid sequence and the resulting protein.
A point mutation could be a silent mutation, maintaining the original amino acid sequence and the resulting protein.
A frameshift mutation is more likely to result in a nonfunctional protein.
1 and # 3 have the same amino acid sequence, therefore they code for the same protein
