Mutations
Mutations
Hollywood’s images of
mutation
Mutations
Ectrodactyly
Progeria
Hypertrichosis
Severe Combined
Immunodeficiency Disorder
(SCID)
Sickle Cell Anemia
Heterochromia iridium
What is a mutation?
@A mutation is any change in a cell’s
DNA@
A mutation can occur in an individual
gene
- results in a single changed protein
- bacterial resistance to antibiotics is
an example of a beneficial gene
mutation
What is a mutation
continued
A mutation can occur in a chromosome
- a chromosome contains many genes
- chromosomal mutations affect many
proteins
Examples: Down Syndrome
Edward’s Syndrome
Cri-du-Chat
What Causes Mutations?
Can be caused by
mutagens
- a physical or
chemical cause of mutation. Examples: UV
light, radiation, drugs, and benzene.
Mutagens are often also
carcinogens
–
anything that causes cancer
Can be natural, random events.
- mutations occur in 1/100,000 DNA
replications
Mutations do not have to be bad (evolution)
Point Mutations
Substitution
@A single nucleotide is altered@. Can
change one amino acid in a protein
Milk – Mil
e
GGAC
A
ATCA GGAC
C
ATCA
proline -
valine
-serine
proline-
glycine
-serine
Frameshift Mutations
@A nucleotide is either inserted or
deleted from a gene.@
-all of the triplets from the point of
mutation onward will be changed
Frameshift Mutations
Insertion
An insertion occurs when a nucleotide is
added to a gene
Example: A nucleotide is inserted
The fat cat ate the rat
The f
a
a tca tat eth era t
-the extra nucleotide
shifts
all of the
triplets that follow
Frameshift Mutations
Deletions
A deletion occurs when a nucleotide is
removed from a gene.
Example: A nucleotide is removed
Th
e
fat cat ate the rat
Thf atc ata tet her at
Insertion
GGACAATCA G
C
GACAATCA
proline -valine-serine
arginine
-
cysteine
-
stop
Deletion
GGA
C
AATCA GGAAATCA
proline -valine-serine
proline-
leucine
C
h
r
o
m
o
s
o
m
a
l
M
u
t
a
t
i
o
n
s
Chromosomal mutations involve changes in the
number or structure of chromosomes.
C
h
r
o
m
o
s
o
m
a
l
M
u
t
a
t
i
o
n
s
Deletion involves the loss of all or part of a
chromosome.
C
h
r
o
m
o
s
o
m
a
l
M
u
t
a
t
i
o
n
s
Duplication produces an extra copy of all or
part of a chromosome.
C
h
r
o
m
o
s
o
m
a
l
M
u
t
a
t
i
o
n
s
Inversion reverses the direction of parts of
a chromosome.
C
h
r
o
m
o
s
o
m
a
l
M
u
t
a
t
i
o
n
s
Translocation occurs when part of one
chromosome breaks off and attaches to
another.
H
a
r
m
f
u
l
a
n
d
H
e
l
p
f
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l
M
u
t
a
t
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o
n
s
The effects of mutations on genes vary
widely. Some have little or no effect; and
some produce beneficial variations. Some
negatively disrupt gene function.
@However, without mutations, organisms
cannot evolve@
Mutations are the source of genetic
variability in a species.
H
a
r
m
f
u
l
E
f
f
e
c
t
s
Some of the most harmful mutations are
those that dramatically change protein
structure or gene activity causing genetic
disorders.
Some cancers, for example, are the
product of mutations that cause the
uncontrolled growth of cells.
http://www.pbs.org/wgbh/nova/cancer/grow_
flash.html
H
a
r
m
f
u
l
E
f
f
e
c
t
s
Sickle cell disease is a disorder
associated with changes in the
shape of red blood cells. Normal red
blood cells are round. Sickle cells
appear long and pointed.
@Sickle cell disease is caused by
a point mutation in one of the
polypeptides found in hemoglobin@.
(the blood’s principal oxygen-
carrying protein)
B
e
n
e
f
i
c
i
a
l
E
f
f
e
c
t
s
Mutations often produce proteins with new or
altered functions that can be useful to organisms in
different or changing environments.
For example, mutations have helped many insects
resist chemical pesticides.
B
e
n
e
f
i
c
i
a
l
E
f
f
e
c
t
s
Plant and animal breeders often make use
of “good” mutations.
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.
Mutations can occur in genes or chromosomes, leading to various conditions like SCID, ectrodactyly, sickle cell anemia, and more. Understand the causes of mutations like mutagens and natural events. Explore different types of gene mutations like point mutations and frameshift mutations, including examples of substitution and insertion.
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Presentation Transcript
Mutations Hollywood s images of mutation
Severe Combined Immunodeficiency Disorder (SCID) Mutations Ectrodactyly Sickle Cell Anemia Heterochromia iridium Progeria Hypertrichosis
What is a mutation? @A mutation is any change in a cell s DNA@ A mutation can occur in an individual gene - results in a single changed protein - bacterial resistance to antibiotics is an example of a beneficial gene mutation
What is a mutation continued A mutation can occur in a chromosome - a chromosome contains many genes - chromosomal mutations affect many proteins Examples: Down Syndrome Edward s Syndrome Cri-du-Chat
What Causes Mutations? Can be caused by mutagens- a physical or chemical cause of mutation. Examples: UV light, radiation, drugs, and benzene. Mutagens are often also carcinogens anything that causes cancer Can be natural, random events. - mutations occur in 1/100,000 DNA replications Mutations do not have to be bad (evolution)
Gene Mutations 1. Point Mutations 2. Frameshift Mutations
Point Mutations Substitution @A single nucleotide is altered@. Can change one amino acid in a protein Milk Mile GGACAATCA GGACCATCA proline -valine-serine proline-glycine-serine
Frameshift Mutations @A nucleotide is either inserted or deleted from a gene.@ -all of the triplets from the point of mutation onward will be changed
Frameshift Mutations Insertion An insertion occurs when a nucleotide is added to a gene Example: A nucleotide is inserted The fat cat ate the rat The faa tca tat eth era t -the extra nucleotide shifts all of the triplets that follow
Frameshift Mutations Deletions A deletion occurs when a nucleotide is removed from a gene. Example: A nucleotide is removed The fat cat ate the rat Thf atc ata tet her at
Insertion GGACAATCA GCGACAATCA proline -valine-serine arginine-cysteine-stop Deletion GGACAATCA GGAAATCA proline -valine-serine proline-leucine
Chromosomal Mutations Chromosomal mutations involve changes in the number or structure of chromosomes.
Chromosomal Mutations Deletion involves the loss of all or part of a chromosome.
Chromosomal Mutations Duplication produces an extra copy of all or part of a chromosome.
Chromosomal Mutations Inversion reverses the direction of parts of a chromosome.
Chromosomal Mutations Translocation occurs when part of one chromosome breaks off and attaches to another.
Harmful and Helpful Mutations The effects of mutations on genes vary widely. Some have little or no effect; and some produce beneficial variations. Some negatively disrupt gene function. @However, without mutations, organisms cannot evolve@ Mutations are the source of genetic variability in a species.
Harmful Effects Some of the most harmful mutations are those that dramatically change protein structure or gene activity causing genetic disorders. Some cancers, for example, are the product of mutations that cause the uncontrolled growth of cells. http://www.pbs.org/wgbh/nova/cancer/grow_ flash.html
Harmful Effects Sickle cell disease is a disorder associated with changes in the shape of red blood cells. Normal red blood cells are round. Sickle cells appear long and pointed. @Sickle cell disease is caused by a point mutation in one of the polypeptides found in hemoglobin@. (the blood s principal oxygen- carrying protein)
Beneficial Effects altered functions that can be useful to organisms in different or changing environments. Mutations often produce proteins with new or resist chemical pesticides. For example, mutations have helped many insects
Beneficial Effects Plant and animal breeders often make use of good mutations. The condition in which an organism has extra sets of chromosomes is called polyploidy.
