Download 12-4 Mutations

Chapter 12: DNA and RNA (12-4)
Sometimes mistakes are made—these mistakes are
called mutations (latin for mutare, “to change”)
 Mutations are changes in the DNA sequence that
affect genetic information
 Gene mutations result from changes in a single
gene. Chromosomal mutations involve changes in
whole or part of chromosomes.
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Point mutations
Affect only ONE nucleotide
One amino acid in the chain is wrong
Substitution of a nitrogen base (A instead of G, etc)
Framshift Mutations
Involve a deletion or substitution of a nitrogen base
Causes a much bigger problem, because the code is
read in 3s
This shifts the “reading frame” of the genetic
message.
Every amino acid is affected after the mutation.
Severely affect the function/shape of the protein.
Chapter 12: DNA and RNA (12-4)
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Change in the number or structure of chromosomes
Deletion—loss of part or all of the chromosome
Duplication—segment of the chromosome is repeated
Inversion—the chromosome is oriented in reverse
Translocation—when part of one chromosome breaks
off and attaches to another non-homologous
chromosome.