Transcript Mutations - Peoria Public Schools

MUTATION
A permanent change in a cell’s DNA.
• Cells have checkpoints to repair damage
missed earlier in DNA replication.
• Sometimes the cell doesn’t repair the
damage.
• If the damage goes unrepaired it can
result in mutation.
CAUSES OF MUTATIONS
•Radiation
(X rays)
•UV light
•Mutagens
• A mutagen is a
substance, such
as a chemical,
that causes
mutations
MAIN CATEGORIES OF MUTATIONS
• Substitution: Involves a chemical change in one base
pair.
• Missense
• Nonsense
• Frameshift: The addition or loss of a nucleotide that
results in a change of the “frame” of the amino acid
sequence
• Insertion
• Deletion
• Duplication: The copying of a nucleotide or amino acid
sequence
MISSENSE MUTATION
A single base
is changed to
cause
substitution of
an amino
acid.
DNA = TAC GAG AGC CCA ATT
RNA = AUG CUC UCG GGU UAA
A.A. = Start leucine serine glycine stop
DNA = TAC
GAG CGC CCA
RNA = AUG CUC GCG
GGU
ATT
UAA
A.A. = Start leucine alanine glycine stop
ACHONDROPLASIA
• Characterized
by the improper
development of
the cartilage in
legs and bones
resulting in
dwarfism
NONSENSE MUTATION
A point
mutation that
results in a
premature
stop codon.
DNA = TAC
GAG
AGC CCA ATT
RNA = AUG CUC
UCG GGU UAA
A.A. = Start leucine serine glycine stop
DNA = TAC
GAG
ATC CCA ATT
RNA = AUG
CUC
UAG GGU UAA
A.A. = Start leucine stop
MUSCULAR DYSTROPHY
Characterized by
the progressive
weakening of
many muscles in
the body
INSERTION MUTATIONS
A mutation in
which bases
are added to
the DNA
sequence
DNA = TAC GAG
AGC
CCA ATT
RNA = AUG CUC
UCG
GGU UAA
A.A. = Start leucine serine glycine stop
DNA = TAC
TGA
GAG
CCC
AAT
RNA = AUG
ACU
CUC
GGG
UUA
A.A. = Start threonine leucine glycine leucine
CROHNS DISEASE
Characterized by
chronic
inflammation of the
intestinal tract
causing diarrhea,
abdominal pain,
nausea, fever
DELETION MUTATIONS
A mutation
in which
part of the
DNA is
missing.
DNA = TAC GAG
AGC CCA ATT
RNA = AUG CUC UCG GGU UAA
A.A. = Start leucine serine glycine stop
DNA = TAC AGA GCC CAA
TTT
RNA = AUG UCU CGG GUU AAA
A.A. = Start serine arginine valine lysine
CRI DU CHAT
• Characterized by a high
pitched cry, similar to a
cat, during infancy
• Symptoms are lowered
intellectual disability,
delayed development,
small head and weak
muscle tone
DUPLICATION
A type of mutation in
which a portion of a
genetic material or a
chromosome is
duplicated or
replicated, resulting
in multiple copies of
that region.
DNA = TAC
GAG
AGC ATT
RNA = AUG CUC
UCG UAA
A.A. = Start leucine serine stop
DNA = TAC
GAG
RNA = AUG CUC
GAG
AGC ATT
CUC UCG UAA
A.A. = Start leucine leucine serine stop
CHARCOT-MARIE TOOTH DISEASE
Characterized by
damage to nerves
leading to atrophy
of muscles in
hands and lower
legs
GENE TRANSLOCATION
• The movement of
a gene fragment
from one
chromosomal
location to another,
which can alter or
abolish expression
SOMATIC VS. GERM CELL MUTATION
Somatic
Germ
• Alters mutated cell and
future daughter cells
• Mutation is passed
on to offspring and
will be present in
every cell of the
offspring
• May cause no result in
a cell if the particular
sequence is not
needed.
• Cell death may occur
• May lead to cancer
• It’s estimated that mutations occur at the
rate of 1 in every 50 million nucleotides.
• This means that each new cell contains
some 120 new mutations. Should we
be worried?
• NO – As much as 97% of our DNA does
not encode anything. “junk DNA”
MUTATION…GOOD?
• Can mutations be
beneficial to us?
• Evolution – The
changes seen in the
inherited traits of a
population from one
generation to the next.