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DNA
Mutations
Mutations Occur 1 of 2 ways
 1.
DNA damage from
environmental agents such as UV
light (sunshine)
 2. Mistakes when copying DNA
DNA Damage from
Environmental agents

EXAMPLES
 Skin
Cells with sun exposure
 Lung cells with cigarette smoke
 Radiation
Cells have the ability to repair damages, but as
an organism ages, DNA repair does not work as
effectively; thus changes occur in the DNA
Original Strand of Nucleotide
Bases
Damage from environmental
agents
Mutation: modifying nucleotide base

When DNA strands are separated and
copied, the altered base will pair with an
incorrect base and cause a MUTATION!
 Environmental
factors
G now pairs with T, instead of forming a normal
pair with ___.
Mutation: breaking phosphate backbone
TRANSLOCATION

Breaking the phosphate backbone of DNA within
a gene creates a mutated form of the gene.
Caused by environmental agents such as
nuclear radiation which can break the bonds
between oxygens and phosphate groups

What might happen if the phosphate
backbone is broken?
Mistakes created during DNA
duplication:
Mutations occur when DNA polymerase
makes a mistake.
 ODDS


1 in 100,000,000 bases
 DNA repair proteins fix many of these
mistakes
What kind of mutations are there?
Point mutation
 Frame-shift mutation

 Deletion
 Insertion
Inversion
 DNA expression mutation

Point Mutations

A simple change in one base of the gene
sequence.
 Original:
Point
The fat cat ate the wee rat.
mutation: The fat hat ate the wee rat.
Changed the ‘c’ in cat to a ‘h’
Frame Shift Mutation

One or more bases are inserted or deleted
but keeps the original spacing.
 Original:
Frame
The fat cat ate the wee rat.
Shift:
The fat caa tet hew eer at.
The ‘t’ from cat was removed, but kept the original
letter spacing.
Deletion

Mutations that occur when DNA is missing.
 Original:
The fat cat ate the wee rat.
Deletion:
The fat ate the wee rat.
Deletion of the word ‘cat’
Insertion

Mutations that occur when extra DNA is
added to the strand, insertions can also
cause frame shift mutations.
 Original:
The fat cat ate the wee rat.
Insertion:
The fat cat cat ate the wee rat.
Extra ‘cat’ added to the sequence
Inversion

An entire section of DNA is reversed.
 Original:
Inversion:
The fat cat ate the wee rat.
The fat tar eew eht eta tac.
cat ate the wee rat is inverted
tar eew eht eta tac


American botanist Barbara
McClintock won the Nobel
Prize for discovering that
corn genes were moving
from one location to another
in the chromosome.
Jumping genes
Studies of
prematurely old
mice hint that
DNA mutations
underlie aging
Darwin’s Finches
Mutations can occur within a gene preventing the
synthesis of the correct protein
“GFP Bunny” comprises the creation of a green fluorescent
rabbit; the use of genetic engineering to transfer natural or
synthetic genes to an organism to create unique living beings.
Mutations Can Be……
Harmful / Lethal
 Beneficial / Adaptive
 Neutral: most common / Variations

Genetic Variations within a
Species