Mutations A mutation is a - PowerPoint Presentation

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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.

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GOOD BAD NEUTRAL

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What base was mutated in DNA?The substitution was a T but it is suppose to be _____.

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Gene Mutations on DNA

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Examples of Gene Mutations

THE

F

AT CAT ATE THE RAT

THE

H

AT CAT ATE THE RAT

THE

ATC ATA TET HER AT

THE

FFA TCA TAT ETH ERA T

Each word represents

an amino acid in a PROTEIN (SENTENCE)

Substitution causesPoint mutation

Sentence or Protein is still readable.

Normal protein or sentence

Deletion causesFrame shift

Duplication orInsertion causesFrame shift

Sentence makes No sense due to Frame Shift

Sentence makes NO sense due to Frame Shift

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Chromosome Mutations

(point, deletion, translocation, )

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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.

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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

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Effects of germ line mutations

No

change occurs in phenotype.

No noticeable

effect

of the phenotype.

Small

change occurs in phenotype

.

ex.

Can cause cat's ears to curl backwards slightly.

Big change occurs in phenotype. Really important phenotypic changes.

ex. DDT resistance in insects or are lethal (causing death)

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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.

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Pepper Moths

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EOC Question

Which will most likely cause variations to occur within a species?

a. Competition

b. Mutation c. Mutualism d.

P

redation

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Random or Spontaneous Mutations

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Spontaneous Mutation of MSTN Gene

MSTN is the

myostatin

geneThe

 

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.

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Spontaneous Mutation

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Myostatin

protein

is not working

t

o maintain normal muscle size.

Question:

The reason the

myostatin

protein

is not working correctly is due to a

____________________.

What does the MSTN gene instruct

the ribosome to make?_________ ______________

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Other Conditions due to Mutations

Tree Man

Wolf Man

Condition caused by a

Mutation in the EVER1

Or EVER2 gene on

Chromosome 17.

Wolf Man Syndrome

i

s caused by a mutation

o

n chromosome 17 which

c

auses abnormal hair growth all over the body.

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Strange Sighting in Asheboro, N.C.

It is believed that this is the same animal several folks spotted in

t

heir backyards. The picture on the left was taken in the day

t

ime 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

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Desirable Mutations in Animals

Scottish Fold

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The name of the mystery animal –SAMPSON FOX

A Sampson fox is an abnormal

Red Fox

who has a MUTATION

t

hat prevents the animals

g

uard hairs from growing.

Normal Red Fox

with guard

hairs.

Sampson fox are very

r

are and usually die

d

ue to environmentalconditions.

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Desirable Mutation for future

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U

Causes

of

Induced

Mutations

Radiation

Chemicals

Smoking Ultra-violet Rays

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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.

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Melanoma (BRAF mutation)

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Mutations caused possibly by parasites

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Mutations Caused by Radiation

Fallout

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Mutations Caused by Chemicals

Mercury in the environment

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Lesson for Drug Safety-Thalidomide

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Other Mutations in Animals

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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

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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.

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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.

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Hemophilia

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Do you recognize any genes that can cause a disorder on this sex chromosome?

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Sickle Cell Anemia

Is this mutation a point or frame shift mutation?

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Sickle cell

disease, hereditary

blood

disorders, occurs almost

exclusively among black Americans and black Africans..

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Sickle Cell causes a great deal of pain fatigue and an enlarged spleen

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Cystic Fibrosis

Caused by mutation in

Protein in plasma

Membrane.

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CF Mutation causes over production of mucus which clogs lungs and intestines (breeding ground for bacteria)

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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 Asian-Americans.

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Alzheimer's disease

I

s 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.

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Notice the plaques

On neurons in

Alzheimer’s brain.

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Kidney Mutations

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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

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Huntington’s causes a wasting

Away of both mind and body.

Huntington’s is

a

lethal mutation.

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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.

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Huntington’s

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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.

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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.

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Testing for PKU

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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.

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Retinoblastoma (cancer of the eye)

M

utated

gene increases susceptibility for retinoblastoma (cancer of the eye that affects approximately 300 children in the United States each year).

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Retinoblastoma

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Tay-Sachs

Lethal Mutation

Tay

-Sachs

allele (gene variant) among Ashkenazi Jews is due to a four base-pair insertion causing a frame shift mutation

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Polydactyly

among the

Amish

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Polydactyly in animals

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Breast Cancer Gene

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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.

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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.

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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.  

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DOWN SYNDROME

Karyotype showing a

TRISOMY

o

n chromosomal pair 21. This

m

utation is due to a

non-disjunction

of chromosomes.

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Other Mutations

Mermaid Syndrome

Apert

Syndrome

Caused by a mutation of the

FGFR2 gene which makes a

Protein called fibroblast growth

Factor receptor 2

Congenital mutation

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Albino Organisms

-Albinism is caused by mutations is 6 known

g

enes.

-An organism with this mutation cannot produce the Melanin pigment protein which gives skin, eyes, and hair color.

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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.

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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.

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Plant Mutation

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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

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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 chemicalsMutations change the amino acid sequence which in turn changes the protein and protein function

ex. sickle cell anemia

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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.

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Mutation needed in Evolution

One process of Natural Selection in a population for genetically variability is

due to mutations and genetic recombination.