Transcript Ch. 10 - Mutations

Mutations
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Mutations are changes in DNA
These can occur in:
• Somatic cells – can cause
tumours/cancers
• Germ-line cells – can cause genetically
inherited disorder
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Spontaneous mutations – have no
known cause
Induced mutations – have a known
cause
Agents that cause mutations are
called ‘mutagenic agents’
Mutagenic Agents
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Some known
mutagenic
agents include:
• Radiation (x-ray,
UV, nuclear)
• Some chemical
substances
(formaldehyde,
mustard gas,
peanut oil)
Types of Mutations
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Substitution – one nucleotide
replaces another
Addition – one or more nucleotide
is inserted into the code without
one being removed
Deletion – removal of one or more
nucleotides without replacement
Substitution mutation
This is called a point mutation because the error only occurs at
the site of mutation it is not carried on afterwards
Addition and Deletion mutation
Addition and
deletion
mutations
usually
result in an
error at the
point where
the mutation
occurs as
well as
every triplet
that occurs
afterwards
This is called
a frameshift
mutation
Some mutations cause more
severe effects than others
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Somatic cell mutations – only
affect the individual not the next
generation
Germ-line mutations are able to
be passed on to the following
generations
Some mutations cause more
severe effects than others
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Mutations only cause problems
when they alter the genetic code
Results in production of:
• Abnormal protein
• Incomplete protein
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Some mutations can affect
promoter regions causing:
• Reduced protein production
• No protein production
What do
you notice
about the
number of
codons
per amino
acid?
Is it possible for a mutation to occur
without affecting protein production?
What
type(s) of
mutation
are likely
to cause
the most
severe
effects?
Why?
DNA repair
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There are a number of enzymes that are
capable of repairing damage to DNA
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In addition, NK T cells are able to
destroy cells that appear to contain
genetic mutations, preventing them
from being replicated