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MUTATIONS
p. 345
A mutation is a change in the DNA sequence. The mutation may be classified as: ______________________ or _____________
mutations. Most mutations are harmful, but a few can be beneficial or silent.
A. Chromosomal Mutation
1. Chromosomal mutations involve the______________________ or __________________ of the entire chromosome. It affects
all genes on that chromosome!
2. These errors generally occur during meiosis or mitosis.
3. May result in a number disorder (extra chromosome or deleted chromosome) insertion, deletion, or translocation of a piece of
chromosome and the corresponding genetic information.
B. Gene Mutation
Gene mutations affect only one gene on an individual chromosome. This may result in a change to only one nucleotide or
_______________ nucleotides. There are two types.
1. Point Mutation: a change at one point in the DNA sequence. This might have no effect or change on an amino acid
sequence. Therefore, the resulting protein may or may not be altered. The incidence of these mutations is relatively low
due to the action of _______________________ that proofread the DNA sequence after ________________________.
a. substitution
2. Frameshift mutations involve the insertion or deletion of a _________________. An insertion or deletion of a nucleotide
causes a shift in the reading of the remainder of the codons; therefore translation of the remainder of the mRNA is altered. This
will usually result in tremendous changes in the polypeptide chain and completed protein.
a. insertion
b. deletion
Chromosomal Mutations:
Gene Mutations
Substitution
Insertion
Deletion