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MUTATIONS
No this can’t happen with just mutations
Mutations are:
• Changes in the DNA code
• Mutations that affect your body cells can
generate changes in your body – things as
serious as cancer, or as simple as moles.
• Mutations that affect your sex cells can be
passed on to your offspring.
• Mutations can happen naturally, but things
called mutagens (like UV radiation) can
make it happen more frequently.
Types of Mutations
• Chromosomal
– Large scale addition, deletion, or change of a
gene or many genes
• Point
– An addition, deletion, or substitution of one (1)
base in a gene.
Types of Point Mutations
Missense Mutation
• Substitution of a base that changes an amino
acid.
• THE CAT ATE THE RAT
• THE CAR ATE THE RAT
– Real life Example: Tay-Sachs Disease
Nonsense Mutation
• Substitution of a base that changes a codon
to a STOP codon.
– Examples: UAC (codes for Tyr)  UAG (a
stop codon)
Frameshift Mutation
• Addition or deletion of a base that causes
the reading frame to shift.
• Example
– THE CAT ATE THE RAT
– (delete the “T” in CAT), shift the frame
– THE CAA TET HER AT
Effects of Mutations
• Silent Mutations: Substitution of a base that
does NOT change the amino acid
– Caused by CODE DEGENERACY: the fact
that most amino acids are coded for by more
than one codon.
• Change of function or Loss of Function
Mutations: will create a new trait.