Transcript Mutations - Duplin County Schools

Mutations
• A mutation is a permanent change in the
DNA sequence of a gene.
• Mutations in a gene's DNA sequence can alter
the amino acid sequence of the protein
encoded by the gene.
GOOD
BAD
NEUTRAL
What base was mutated in DNA?
The substitution was a T but it is
suppose to be _____.
Gene Mutations on DNA
Examples of Gene Mutations
Each word represents
an amino acid in a
PROTEIN (SENTENCE)
THE FAT CAT ATE THE RAT
Normal protein or sentence
THE HAT CAT ATE THE RAT
Substitution causes
Point mutation
Sentence or Protein is still readable.
THE ATC ATA TET HER AT
Sentence makes No sense due to Frame Shift
Deletion causes
Frame shift
THE FFA TCA TAT ETH ERA T
Sentence makes NO sense due to Frame Shift
Duplication or
Insertion causes
Frame shift
Chromosome Mutations
(point, deletion, translocation, )
Definitions
• Somatic cell mutation- mutation in body cell
*Not passed to offspring
ex. Lung cancer
Q. If a mother has lung cancer or skin cancer and gets pregnant
will her child be born with lung or skin cancer?
• Germline mutation – mutation in the sex cells,
the egg and sperm or gametes.
ex. BRCA1 and BRCA2 (breast cancer and ovarian cance
genes)
*Can be passed to offspring generation after generation,
less common.
EOC Question
• Which would most likely produce a mutation
that is passed on to offspring?
a. Radiation changing the DNA sequence in
skin cells
b. A gamete with an extra chromosome forming
c. Tobacco smoke altering the genes in lung cells
d. Exposure to chemicals altering nerve cell
function
Effects of germ line mutations
1. No change occurs in phenotype.
No noticeable effect of the phenotype.
2. Small change occurs in phenotype.
ex. Can cause cat's ears to curl backwards
slightly.
3. Big change occurs in phenotype.
Really important phenotypic changes.
ex. DDT resistance in insects or are lethal (causing
death)
Evolution and Mutation
• Mutations are the raw materials of
evolution.
• Evolution absolutely depends on mutations
because this is the only way that new
alleles and new regulatory regions are’
created.
Pepper Moths
EOC Question
• Which will most likely cause variations to
occur within a species?
a. Competition
b. Mutation
c. Mutualism
d. Predation
Random or Spontaneous Mutations
Spontaneous Mutation of MSTN Gene
• MSTN is the myostatin gene
• The MSTN gene provides instructions for
making a protein called myostatin which is
active in muscles used for movement.
• This protein normally restrains muscle growth,
ensuring that muscles do not grow too large.
• Mutations lead to an overgrowth of muscle
tissue.
Spontaneous Mutation
Myostatin protein is not working
to maintain normal muscle size.
Question:
1. The reason the myostatin protein
is not working correctly is due to a
____________________.
2. What does the MSTN gene instruct
the ribosome to make?_________
______________
Other Conditions due to Mutations
Tree Man
Condition caused by a
Mutation in the EVER1
Or EVER2 gene on
Chromosome 17.
Wolf Man
Wolf Man Syndrome
is caused by a mutation
on chromosome 17 which
causes abnormal hair
growth all over the body.
Strange Sighting
in Asheboro, N.C.
It is believed that this is the same animal several folks spotted in
their backyards. The picture on the left was taken in the day
time when the animal would be seen. The picture on the right
was taken by a hunting camera mounted on a tree at night.
Q. What is this animal? Is a combination of animals?
2013
Desirable Mutations in Animals
Scottish Fold
The name of the mystery animal –
SAMPSON FOX
A Sampson fox is an abnormal
Red Fox who has a MUTATION
that prevents the animals
guard hairs from growing.
Normal Red Fox
with guard
hairs.
Sampson fox are very
rare and usually die
due to environmental
conditions.
Desirable Mutation for future
U
Causes of
Induced Mutations
Radiation
Chemicals
Smoking
Ultra-violet Rays
SKIN CANCER
• Skin cancer occurs when errors (mutations)
occur in the DNA of skin cells.
• The mutations cause the cells to grow out of
control forming cancer cells.
Melanoma (BRAF mutation)
Mutations caused possibly by parasites
Mutations Caused by Radiation
Fallout
Mutations Caused by Chemicals
Mercury in the environment
Lesson for Drug Safety-Thalidomide
Other Mutations in Animals
EOC Question
• A large population of cockroaches was sprayed with an
insectide. A few of the cockroaches survived and produced a
population of cockroasches that was resistant
to this spray. What can best be inferred from
this example?
a. A species will adapt no matter what the environment
B. The environment has no effect on the survival of an
organism
c. Insecticides cause mutations that are passed on to the
next generation.
d. Individuals with favorable variations survive and
reproduce
EOC (tricky one!)
• The use of pesticides on crops has been a common farming
practice for decades. What has been the greatest effect of
natural selection through the use of pesticides on certain insect
population?
a. Natural selection has been altered because
the insects and their predators are killed.
b. The rate of selection is increased because
the pesticides do not kill the insects that
are naturally resistant to it.
c. The rate of selection has decreased because the pesticides
kill only young insects.
d. The pesticides have altered natural selection by causing the
insect DNA to spontaneously mutate.
Hemophilia
• Hemophilia is caused by mutation in the X sex
chromosome.
• Hemophilia can be inherited, or it may be caused
by a spontaneous mutation of the factor gene.
• Approximately 30% of cases of hemophilia are
caused by a spontaneous mutation of the gene.
In these cases, the mother is not a carrier of
hemophilia and the child affected is the first in
the family to have hemophilia and to carry the
defective factor gene.
Hemophilia
Do you recognize any genes that can
cause a disorder on this sex
chromosome?
Sickle Cell Anemia
Is this mutation a point or frame shift mutation?
Sickle cell disease, hereditary blood disorders, occurs almost
exclusively among black Americans and black Africans..
Sickle Cell causes a great deal of pain
fatigue and an enlarged spleen
Cystic Fibrosis
Caused by mutation in
Protein in plasma
Membrane.
CF Mutation causes over production of
mucus which clogs lungs and intestines
(breeding ground for bacteria)
Cystic fibrosis (CF) is the most common inherited fatal disease of
children and young adults in the United States. CF occurs in about 1 out of
3,200 whites, 1 out of 15,000 African-Americans, and 1 out of 31,000 AsianAmericans.
Alzheimer's disease
• Is not a normal consequence of growing
older, and scientists are continuing to seek its
cause.
• Mutations in four genes, situated on
chromosomes 1, 14, 19, and 21, are thought
to be involved in the disease, and the best
described are PS1 (or AD3) on chromosome
14 and PS2 (or AD4) on chromosome 1.
Notice the plaques
On neurons in
Alzheimer’s brain.
Kidney Mutations
HUNTINGTON'S DISEASE
• Huntington's disease (HD) is an inherited,
progressive brain disorder.
• It causes the degeneration of cells in the basal
ganglia, a pair of nerve clusters deep in the
brain that affect both the body and the mind.
• HD is caused by a single dominant gene that
affects men and women of all races and ethnic
groups
Huntington’s is
a lethal mutation.
Huntington’s causes a wasting
Away of both mind and body.
HUNTINGTON’S Mutation gene
• The gene mutation that produces HD was mapped to
chromosome 4 in 1983.
• The mutation involves a triplet of nucleotides, cytosine (C),
adenine (A), and guanine (G), known as CAG.
• The mutation is an expansion of a nucleotide triplet repeat
in the DNA that codes for the protein huntingtin.
• In unaffected people the gene has thirty or fewer of these
triplets, but HD patients have forty or more. These
increased multiples either destroy the gene's ability to
make the necessary protein or cause it to produce a
misshapen and malfunctioning protein.
• Either way, the defect results in the death of brain cells.
Huntington’s
HD does not usually strike until mid-adulthood,
between the ages thirty and fifty,
• HD affects 3 to 7 per 100,000 people of European
ancestry. HD appears to be less common in other
populations, including people of Japanese,
Chinese, and African descent.
PHENYLKETONURIA (PKU)
• (PKU) is caused by a gene-environment
interaction.
• The affected individual is unable to convert
phenylalanine into tyrosine.
• Phenylalanine accumulates in the blood and
can reach toxic levels.
• Toxicity levels may impair brain and nerve
development and result in mental retardation,
organ damage, and unusual posture.
Testing for PKU
PKU
• Recognition of dietary phenylalanine as a
critical environmental trigger has enabled
children born with PKU to lead normal lives
when they are placed on low-phenylalanine
diets.
• Mothers with the disease can bear healthy
children.
Retinoblastoma (cancer of the eye)
• Mutated gene increases susceptibility for
retinoblastoma (cancer of the eye that affects
approximately 300 children in the United
States each year).
Retinoblastoma
Tay-Sachs
• Tay-Sachs allele (gene variant) among
Ashkenazi Jews is due to a four base-pair
insertion causing a frame shift mutation
Lethal Mutation
Polydactyly among the Amish
Polydactyly in animals
Breast Cancer Gene
• Actress Angelina Jolie has revealed
that she had a double mastectomy
after she learned that she carries a
mutated version of the gene
BRCA1.
• She had a very high risk of breast
cancer.
• She explained her decision in a
New York Times article. Here are
some questions her story may
raise for other women.
Q: What is the BRCA1 gene?
A: BRCA1 (pronounced brak-uh) stands for
“breast cancer one.”
First mutated gene that scientists discovered
among families whose histories revealed many
cases of breast cancer.
Ovarian cancers also are common in such
families. A second such gene is known as BRCA2.
• Q: How high is the cancer risk in women who
carry the mutations?
• A: Women with the BRCA1 or BRCA2
mutations have an average breast cancer risk
of 60 percent.
• Men with the mutations have higher breast
cancer risks than other men do.
• Jolie’s mother died of ovarian cancer at age
56, says her personal risk was estimated at 87
percent.
• Q: Should all women be tested for these
mutations?
• A: No. Jolie says the tests can be expensive.
DOWN SYNDROME
Karyotype showing a TRISOMY
on chromosomal pair 21. This
mutation is due to a non-disjunction
of chromosomes.
Other Mutations
Mermaid Syndrome
Congenital mutation
Apert Syndrome
Caused by a mutation of the
FGFR2 gene which makes a
Protein called fibroblast growth
Factor receptor 2
Albino Organisms
-Albinism is caused by mutations is 6 known
genes.
-An organism with this mutation cannot produce
the Melanin pigment protein which gives skin,
eyes, and hair color.
Purposely Mutating Genes
(New Technology)
• A new, fast and inexpensive way to mutate
genes and large, non-gene pieces of DNA has
been developed by University of Utah
geneticists.
• WHY? The new method promises to speed
efforts to learn more about how non-gene
portions of DNA control genes to cause
human defects and diseases.
They tested the method by mutating a gene involved
in bone formation, resulting in short, malformed tail
and limbs in the mutant mouse on the left, compared
with the skeleton of a normal mouse on the right.
Plant Mutation
Summary of mutations
• Sources of genetic variation in sexually
reproducing organisms includes:
*crossing over in meiosis
*gene mutations
*nondisjunction (chromosomal mutation)
*fertilization
*random assortment of chromosomes
Summary continued
• Mutations are changes in DNA coding
• Mutations can be deletions, additions, or
substitutions ex. hemophilia caused by all 3
• Mutations can be RAMDOM and spontaneous
ex. ear lobe phenotype
• Mutations can be caused by radiation ex.
melanoma (skin cancer)
• Mutations can be caused by chemicals
• Mutations change the amino acid sequence
which in turn changes the protein and protein
function ex. sickle cell anemia
Summary continued
• Mutations can change the phenotype
(outward appearance) of an organism.
Ex. mutation in hemoglobin pigment enzyme
caused the blue color of Marvin Fugate
• ONLY mutations in sex cells (egg and sperm),
also called gametes, can result in heritable
change. (mutations in sex cells can be passed
to offspring)
Ex. BRCA1 breast cancer gene is passed from
mother to offspring.
Mutation needed in Evolution
• One process of Natural Selection in a
population for genetically variability is
due to mutations and genetic recombination.