Sci 30 Chapter 2.4 Mutations and Genetic Diseases

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Topic 2.4 Mutations and

Genetic Diseases

Science 30

Chapter 2 page 116

10/7/20

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Mutations and Genetic Diseases



Change in the sequence of bases along

DNA molecule



These changes are carried forward in

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Mutations and Genetic Diseases



Relationship between a DNA mutation

and a protein:

 _{Change in bases means change in codons}

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Mechanisms of Mutation:



Point Mutation:

 _{Substitution of one nucleotide base for}

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Point Mutation Example

Sickle cell anemia is caused by a point mutation in the DNA that codes for

hemoglobin.

The mutation involves

changing one DNA base that changes one amino acid in the hemoglobin protein.

AS A RESULT THE MUTATED

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Mechanisms of Mutation:

 Frameshift mutation:

 _{DELETION or ADDITION of a nucleotide during}

DNA replication.

 _{Causes the three letter codons or frames in DNA to}

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Passing on Mutations (page 119-120)



Mutation in Body (Somatic)

Cells:



little effect on body, if cell doesn’t

work it will just die



Mutation in Gametes (Sex) Cells:



mutated gene present in every cell

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Passing on Mutations (page 119-120)



Genetic Disease:



A disease caused by a mutation of

one or more genes that can be

inherited by future generations



Carrier:



An individual who has the

allele

for

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Using page 120 of your textbook fill in the following chart

Genetic Disease

_{Cystic fibrosis (CF)}

Location

of Gene

7

Mechanism of

Inheritance

Autosomal recessive

Possible genotypes

_{f f}

Symptoms

_{Sticky mucous}

produced in lungs and

digestive tract

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CF

 The median

survival age in Canada has

increased from 24 in 1982 to 47.7 in 2007, based on data compiled by the Canadian Cystic Fibrosis Foundation.

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Genetic Disease Huntingtons Disease

Location of Gene

₄

Mechanism of

Inheritance

Autosomal dominant

_Hh

HH

Symptoms

_{Brain cell death (late}

onset)

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Huntington’s Disease

 neurodegenerative genetic

disorder that affects muscle coordination and leads

to COGNITIVE DECLINE AND DEMENTIA

 It typically becomes noticeable

in middle age

 Autosomal dominant mutation

Affected if you are homozygous

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Genetic Disease Hemophilia

Location of Gene

_X

Mechanism of

Inheritance

Sex-linked

_X

h

Y

X

h

X

h

Symptoms

_{Do not clot}

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Hemophilia



Bleeding disorder



Blood

DOES NOT CLOT

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 1. A couple discovers that they both have a family history

of cystic fibrosis. They are thinking of having a child, and they ask for a genetic test to be done. Both the man and the woman discover that they are carriers of the recessive cystic fibrosis allele. Build a Punnett square to describe this cross.

a) What is the percentage probability that their child will develop

cystic fibrosis?

b) What is the percentage probability that their child will be a

carrier of the cystic fibrosis allele?

c) What is the percentage probability that their child will not

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Cystic Fibrosis

F

f

F

F F

F f

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 A man is heterozygous for the dominant

Huntington allele, and he has a child with a

woman who does not have a Huntington allele. Build a Punnett square to describe this cross.

a) Write the possible offspring genotypes from this

cross.

b) What is the percentage probability that their child

will not develop Huntington disease?

c) What is the percentage probability that their child

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Huntington’s

h

H

H h

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 A woman carries one of the defective recessive

alleles on her X chromosome that causes

hemophilia. She has a child with a man who does not possess the hemophilia allele. Build a Punnett square to describe this cross.

a) What is the percentage probability that she will have

a child with hemophilia?

b) What percentage of females born from this cross are

likely to have hemophilia?

c) What percentage of males born from this cross are

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hemophilia

X

H

Y

X

H

X

H

X

H

X

H

Y

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Factors That Increase Mutations



Mutagen:



an agent that causes the likelihood of

mutations to increase



Cancer:



out of control growth of cells with no

function



Carcinogenic:

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A.POINT MUTATION

B.TYROSINE

C.STOP

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A.FRAMESHIFT

B.GLYCINE-LEUCINE-GLUTAMATE

C.GLYCINE-ISOLEUCINE-ARGININE

D.AMINO ACID CHAIN IS

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Topic 2.4 - Pedigree

Charts

Page 123 Science 30

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Tracing Genetic Disease: Pedigree Charts



Pedigree:

a tool with

symbols used to trace

a particular trait



Pedigree charts are

used in

genetic

counseling

to predict

the probability of a

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Types of pedigrees

:



Autosomal vs sex-linked:



Autosomal -

Both sexes affected equally



_{Sex-linked –}

_{males more affected than}

females



Dominant vs Recessive



Males and Females equally have disorder



_{Dominant is seen in}

_{every generation}

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X-Linked Recessive

 Males are almost exclusively affected.

 No father to son transmission occurs but all

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X-Linked Recessive

 Carrier females have a 50% or 1 in 2 chance of

having an affected son and a 50% or 1 in 2 chance of having a carrier daughter.

X

R

Y

X

R

X

R

X

R

X

R

Y

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Y-Linked

 Male pass the trait to their

sons.

 EVERY son will be

affected

 Daughters are NEVER

affected = no Y chromosome

 Y chromosome is very

small and does not contain many genes

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Practice – Answer questions 42 to 44 on page 124 AND Q# 4 on page 128 in the space below

42. a.

The number of people with the albino

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Practice – Answer questions 42 to 44 on page 124 AND Q# 4 on page 128 in the space below

42. b.

Individual III-1 has albinism, but both

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Beneficial Mutations Affect

Populations-Evolution



Mutations can be

BENEFICIAL

as well

as harmful



In evolution and Darwin’s theory of

survival of the fittest through natural

selection,

organism best able to SURVIVE

in an environment reproduce and pass

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Beneficial Mutations Affect

Populations-Evolution



Mutation plays a key role in

EVOLUTION



Mutation is a source of

VARIATION

in a

population by producing new alleles.

 If these new alleles result in advantageous

traits, organisms with the traits have a better chance of survival in the environment.



Organisms that survive can pass other

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Resistance in Bacteria (page 126)



Describe how bacteria (or viruses)

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Resistance in Bacteria

 In addition to mutations … bacteria also develop

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Resistance in Bacteria

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Genetic Technologies

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Genetic Technologies in Hollywood

Jurassic Park (1993)

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1. DNA Fingerprinting

 Although long stretches of the DNA molecule are

similar from one person to another, particular

segments contain unique arrangements of nitrogen bases.

 Only identical twins or triplets share the same

nitrogen base arrangements in these segments.

 DNA fingerprinting techniques separate an

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DNA Fingerprinting

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1. DNA Fingerprinting



Purposes of producing

DNA fingerprints

:



Paternity Test,

Criminal

Investigation



DNA sources:



Hair, saliva, blood,

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Gel Electrophoresis

 _{Gel electrophoresis is a method that separates large molecules (including} DNA and proteins) on the basis of size, electric charge and other physical properties. Such molecules possess a slight electric charge. DNA is

negatively charged because the phosphates that form the backbone of a DNA molecule have a negative charge. To prepare DNA for gel

electrophoresis the DNA is cut up into smaller pieces by mixing it with restriction enzymes. This produces a range of DNA fragments of

different lengths. During electrophoresis, molecules are forced to move through the pores of a gel (jelly-like material) when an electrical current is applied. The electrical current from an electrode at one end of the electrophoresis change repels the molecules while the electrode at the other end attracts the molecules. The migration of the DNA fragments through the gel is determined by their size. Smaller fragments move

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Question!

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Example from your notes booklet:

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Genetic engineering

https://www.youtube.com/watch?v=6cQLGKH2ojY

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2. Transgenics

a)

Define genetic

engineering:



_Direct

manipulation of an

organisms genome

using

biotechnology



Insert new DNA in

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One type of genetic engineering is transgenics:



Define the process of

transgenics:



_{Inserting a gene into a}

living organism so that

the organism will

exhibit and transmit

this trait onto its

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Results of transgenics



Define GMO

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GMO examples



Corn



Soy beans



Sugar beets



Potato



Tomatos

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The debate …

PROs

 Grow more food  Higher level of

nutrients

 Fast growing

 Prevent spread of

diseases in a crop if they are resistant

CONs

 Don’t know long

term effects of eating GMO foods

 Expensive

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3. Applying Transgenics-Medicines and Gene Therapy

 Define recombinant DNA:

DNA containing genes spliced from two

different organisms

Structure Function

Restriction

Enzyme

DNA scissors

Ligase Enzyme

_{DNA glue}

Bacterium

Plasmid

Small circle of DNA in

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Describe how human insulin (or other drugs) can be produced by recombinant DNA

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Recombinant DNA Technology



https://

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Define Gene Therapy



Technique of using a vector (virus) to

repair or replace a defective gene in the

treatment and cure of genetic diseases

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