Mutations and gene regulation

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Transcript Mutations and gene regulation

Mutations and gene regulation
lecture 12-4, 12-5
What are Mutations? Changes in the
genetic material.
12-4 Mutations
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Kinds of Mutations
• Substitutions
usually affect no
more than a
single amino
acid.
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Insertion
• An extra base is
inserted into a base
sequence.
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Deletion
• A single base is deleted and the reading frame
is shifted.
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Chromosome Mutations: changes to
the whole chromosome
• Deletions
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• Inversions reverse the direction of parts of
chromosomes.
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• Translocations : part of one chromosome breaks off
and attaches to another.
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Significance
• Many mutations are
neutral.
• Some can cause genetic
diseases.
• Some can be helpful,
like resistance to HIV, or
polyploidy in plants.
How does DNA make different cells?
• All cells have a full
set of DNA
• Not all the DNA is
expressed in each
one
• Promoters and
repressors allow
only certain genes
to be expressed
(make protein)
Nerve, cardiac, muscle, white blood cells
Gene expression
• Cells turn their genes on and off as needed.
• Repressor proteins stop expression of a gene.
• The gene is activated when the repressor is
removed.
The gene that breaks down lactose is repressed
• When lactose is added, it binds to the repressor
protein.
When lactose binds to the repressor, it moves
away, allowing the protein to be made.
Hox genes
• Hox genes control the
basic structure of many
animals.
• They are inherited from
the genes of our
common ancestors.