Name: ____________________________________ Period: _____ Date: ___________
Mutation Notes
MUTATIONS:
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A source of variation
A change in the nucleotide base sequence of the DNA or a change in the
structure or number of chromosomes
May occur in somatic cells (aren’t passed to offspring)
May occur in gametes (eggs & sperm) and be passed to offspring
Mutagens cause mutations which are mistakes in the base sequence of the
DNA. (If you change the recipe, you change the product)
There are two types:
Point mutations (changing a single nucleotide base)
1. Substitution: mutations involve replacing one base with another.
2. Deletion mutations remove or delete a base
FRAMESHIFT MUTATIONS
3. Insertion mutations add an extra base
Chromosomal mutations (Having an extra chromosome or one too few)
1. Deletion (of more than just one nucleotide/base)
2. Inversion
3. Translocation
4. Nondisjunction (Sometimes, chromosomes fail to separate during 1st
or 2nd stages of meiosis)
5. Duplication
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Mutations happen regularly and almost all mutations are neutral
Chemicals & UV radiation cause mutations
Many mutations are repaired by enzymes
Some type of skin cancers and leukemia result from somatic mutations
Some mutations may improve an organism’s survival (beneficial)
Karyotype: Pictures of chromosomes pairs
Name: ____________________________________ Period: _____ Date: ___________
Mutation Notes
In each of the following DNA sequences, you will use the mRNA and amino acid
sequences to identify the mutation that occurred and the effects of each. Look
and analyze carefully!
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? (Circle the change)
Will there likely be effects?
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? (Circle the change)
Will there likely be effects?
What kind of mutation is this?
Mutated DNA Sequence #3:
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?
T A C A C C T T A G C G A C G A C T