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Gene Mutation

Gene mutations are changes in the DNA code that result in changes to genes. Mutations occur at a frequency of about one in every billion base pairs. While everyone has around six mutations in each cell of their body, mutations are not always harmful - they may have no effect, be beneficial, or be harmful. Point mutations such as substitutions, insertions, and deletions can change the amino acid sequence of proteins. Deletion and insertion mutations are more likely to significantly affect an organism since they disrupt the coding frame, while substitution mutations may or may not affect the resulting protein. Mutagens like radiation and chemicals can induce mutations by damaging DNA.

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محمد رعد
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125 views19 pages

Gene Mutation

Gene mutations are changes in the DNA code that result in changes to genes. Mutations occur at a frequency of about one in every billion base pairs. While everyone has around six mutations in each cell of their body, mutations are not always harmful - they may have no effect, be beneficial, or be harmful. Point mutations such as substitutions, insertions, and deletions can change the amino acid sequence of proteins. Deletion and insertion mutations are more likely to significantly affect an organism since they disrupt the coding frame, while substitution mutations may or may not affect the resulting protein. Mutagens like radiation and chemicals can induce mutations by damaging DNA.

Uploaded by

محمد رعد
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We take content rights seriously. If you suspect this is your content, claim it here.
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GENE

MUTATION BY

DR.AMIR SALEH DR.YOUSIF DEAA DR.TAHR


What is a gene mutation?

mutations are changes in


genetic material – change in
DNA code thus a change
in a gene

In gene mutations, the DNA


code will have a base (or
more)
Missing, added,or
exchanged in a code
How common are mutations

Mutations occurs at a frequency of


about 1 in every 1 billion base pairs

Everybody has about 6 mutations in


each cell their body!
If I have that many mutations,why
do not I look weird?
Mutations are not always seen.
The afected gene may still funaction.
mutations may be

no efect benefcial
harmful on organism
How do mutations efect a population?

Mutations are a major source of


genetic variations in a population
.increasing biodiversity

Some variations may help them to


.survive better
How are mutations in inherited?

Only mutations in gametes (egg &


sperm) are passed onto ofspring.

Mutations in body cells only afect


the organism in which they occur
and are not passed onto ofspring.
Types of gene mutations

Point mutation: occurs when the base


sequence of a codon is changed.
(ex.GCA is changed to GAA)
there are 3 types
1. Substitution
2. Deletion also called
3. Insertin frameshift
mutations
Substitution mutations

Normal DNA: CGA- TGC- ATC


Alannine-threonine-stop

Mutated DNA: CGA- TGC- TTC


Alanine-threonine-lysine

What has happened to the DNA?


Substitution Mutations

A single nitrogen base is substituted


for another in a codon.

It may or may not afect the amino


acid or protien.
Insertion Mutations

Normal DNA: CGA- TGC- ATC


Alanine-threonine-stop

Mutated DNA: CGA- TAG- CAT- C


Alanine- Isoleucine-
valine

What has happened to the DNA?


Insertion mutations

A nitrogen base is inserted/added to


the sequence.

It causes the triplet frames to shift.

It always afects the amino acids


and, consequently, the protein
Deletion Mutations

Normal DNA: CGA- TGC- ATC


Alanine- threonine- stop

Mutated DNA: CGA- TCA- TC


Alanine- serine

What has happened to the DNA?


Deletion Mutation

A nitrogen base is deleted/removed


from the sequence.

It causes the triplet frames to shoft.

It always afect the amino acids and,


consequently, the protein.
Gene Mutation

Which mutation would have the least afect on an


organism?
Normal DNA: CGA- TGC- ATC
Alanine- threonine- stop
Mutated DNA: CGA- TGC- ATT
Alanine- threonine- stop
Muated DNA: CGA- TGC- ATG
Alanine- threonine- tyrosine
Substitution: has the least afect because it
change only one amino acid or it may change no
amino acid.
Gene Mutations

An example of a substitution
mutation is sickle cell anemia.
Only one amino acid changes in the
hemoglobin.
The hemoglobin still functions but it
folds diferently changing the shape
of the rbc.
Gene Mutations
Which mutation would have the most
afect on an organism?
Insertion and deletion mutations have
the most efect on an organism because
they afect many amino acids and
consequently the whole protein
Normal DNA: CGA- TGC- ATC
Alanine- threonine-stop
Mutated DNA: CGA- TCA-TC
Alanine- serine
Mutated DNA: CGA- TAG- CAT- C
Alanine-leucine-valine
Gene Mutations

Huntington’s Disease is caused by


an insertion mutation.
The gene mutation have the greater
afect on an organism in the gamete
(egg or sperm) or early in embryonic
development(in stem cells or frst
few days).
mutagens

What causes mutations?


A natural errors or an environmental
event

What is mutagens?
Something that causes the DNA
code to change(mutate)- x-ray,
chemicals, UV light, radiation,etc
THE END

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