topic 3.4 - inheritance2018/08/03 · inheritance with experiments in which large numbers of pea...

TOPIC 3.4 - INHERITANCE

3.4 – A – Inheritance & Alleles

Understandings

U1: Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

Key Terms

Gregor Mendel

IB BIO – 3.4 3Gregor Mendel was an Austrian

monk who is known as the

father of genetics.

He noted that pea plants in his

garden had characteristics that

were sometime passed on to

offspring.

http://res.cloudinary.com/dk-find-out/image/upload/q_80,w_1440/A-Alamy-DG0PF5_bnhdua.jpg

Understandings


Key Terms

Gregor Mendel

IB BIO – 3.4 4

http://archive.cnx.org/resources/fa6f545cec588d620656d63cefaa1ad4c528df03/Figure_08_01_03.jpg

To study how pea plants pass on traits, he bred plants for that were

pure for seven traits. Those traits included:

Understandings


Key Terms

Gregor Mendel

IB BIO – 3.4 5

http://www.grossmont.edu/people/bonnie-yoshida-levine/images/images/Genetics/MendelPeas.jpg

Then, he crossed large numbers

of plants with different

characteristics to determine

which traits would appear in

offspring.

His observations allowed him to

discover the principles of

inheritance which are discussed

in this topic.

*See the video at the end of this

Topic for further explanation

Understandings

U2: Gametes are haploid so contain only one allele of each gene.

U3: The two alleles of each gene separate into different haploid daughter nuclei during meiosis.

Key Terms

Haploid / Diploid

IB BIO – 3.4 6

A zygote results when two gametes fuse

together. It is able to grow and develop

into an adult organism.

http://www.mun.ca/biology/desmid/brian/BIOL2060/BIOL2060-20/20_14.jpg

As discussed in Topic 3.3, meiosis results in haploid gametes, which

only contain half the chromsomes and one allele of each gene.

Understandings

U2: Gametes are haploid so contain only one allele of each gene.

U3: The two alleles of each gene separate into different haploid daughter nuclei during meiosis.

Key Terms

IB BIO – 3.4 7

http://www.mun.ca/biology/desmid/brian/BIOL2060/BIOL2060-20/20_14.jpg

During gamete production, the two alleles for a gene segregate into

different daugher nuclei. The overall combination of alleles in the

resulting cells is random, promoting variation.

Understandings

U4: Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.

Key Terms

IB BIO – 3.4 8When gametes fuse, the resulting diploid zygote has two alleles for

every gene. These alleles may be the same or different.

• Heterozygous – the two alleles for a gene are different

• Homozygous – the two alleles for a gene are the same

https://www.genome.gov/dmd/previews/85182_large.jpg

Understandings

U4: Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.

Key Terms

IB BIO – 3.4 9

Determine whether the following are Heterozygous or Homozygous

http://ysalazar.weebly.com/uploads/4/2/0/8/42086445/beginning_genotype_phenotypes.png

Practice

Understandings

U5: Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.

Key Terms

Genotype

Phenotype

IB BIO – 3.4 10When discussing inherited traits, two important terms are used:

• Genotype – the combination of alleles an organism has, typically

shown using pairs of letters.

• Phenotype – the observable physical characteristics

http://2.bp.blogspot.com/--L23zo3HS1Q/UDe7eJfgGBI/AAAAAAAAAL4/4iPO3ncnC8Y/s1600/25_environmental_variation.gif

Understandings


Key Terms

Dominant Allele

Recessive Allele

IB BIO – 3.4 11Some alleles are able to mask the effects of others when they are

present. These are called dominant alleles and are represented

using upper case letters (A = purple).

Recessive alleles are those that are masked by dominant alleles.

They are represented using lower case letters (a = white).

http://www.cubocube.com/files/images/opengenetics/chapter3/image3.png

Understandings


Key Terms

IB BIO – 3.4 12

Determine the phenotype in the following examples

http://ysalazar.weebly.com/uploads/4/2/0/8/42086445/beginning_genotype_phenotypes.png

Practice

Understandings


Key Terms

Co-dominant Allele

IB BIO – 3.4 13Co-dominance occurs when co-dominant alleles are present. These

have joint effects and so are both seen in the phenotype. In the

example here, red and white alleles mix to form a pink flower.


VID

EO

SIB BIO – 3.4 14

• TedEd – How Mendel’s Pea Plants Helped Us

Understand Genetics

• CrashCourse - Heredity

https://www.youtube.com/watch?v=Mehz7tCxjSE

https://www.youtube.com/watch?v=CBezq1fFUEA

REVIE

WIB BIO – 3.4 15

1. Outline Mendel’s use of peas in discovering

principles of genetics.

2. Describe the segregation of alleles during meiosis.

3. Define the following:

- Genotype - Phenotype

- Heterozygous - Homozygous

4. Compare the effects of dominant and recessive

alleles.

5. Describe co-dominance using an example.

3.4 – B – Monohybrid Crosses

Skills

S1: Construction of Punnett grids for predicting the outcomes of monohybrid genetic crosses.

Key Terms

Punnett Grid

Monohybrid Cross

IB BIO – 3.4 17

http://1.bp.blogspot.com/-vX7FvvV9e6o/VkbmOhmc8tI/AAAAAAAAAus/-PivO6ldyF8/s1600/monohybrid-cross-punnett-square.png

Punnett grids are a tool that can

be used to predict the outcomes

of monohybrid crosses. These

are crosses that involve the

study of a single trait.

Skills


Key Terms

Punnett Grid

Monohybrid Cross

IB BIO – 3.4 18

https://www.biologycorner.com/resources/punnett_1_answers.gif

Using Punnett Grids

1. Determine the genotype of the parents and write them as a cross

(i.e. Rr x Rr).

_______ X _________

2. Write the genotypes

of the parents on the

top and left side of

the Punnett grid.

There should be one

allele per box on each

side.

Skills


Key Terms

Punnett Grid

Monohybrid Cross

IB BIO – 3.4 19

https://www.biologycorner.com/resources/punnett_1_answers.gif

Using Punnett Grids

3. Use the genotypes on the outside of the grid to fill in the squares

with completed genotypes.

4. Determine the number of each type of genotype and phenotype.

This can be used to predict ratios of offspring.

Skills


Key Terms

Punnett Grid

Monohybrid Cross

IB BIO – 3.4 20

https://d2gne97vdumgn3.cloudfront.net/api/file/iOA8caDKSK2Th0aVHRNg

Punnett Grid Example 1

A heterozygous yellow pea plant is crossed with a homozygous

green pea plant. What percentage of offspring will be yellow?

Y = yellow (dominant)

y = green (recessive)

Yy x yy

Genotype:

- 50% yy

- 50% Yy

Phenotype:

- 50% green

- 50% yellow

Skills


Key Terms

Punnett Grid

Monohybrid Cross

IB BIO – 3.4 21

https://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Punnett_homobrown_x_hetero.svg

Punnett Grid Example 2

A heterozygous brown-eyed man reproduces with a homozygous

brown-eyed woman. What portion of offspring will be blue-eyed?

B = brown (dominant)

b = blue (recessive)

BB x Bb

Genotype:

- 50% Bb

- 50% BB

Phenotype:

- 100% brown

- 0% blue

Applications

A1: Inheritance of ABO blood groups.

Key Terms

Blood Type

IB BIO – 3.4 22

https://upload.wikimedia.org/wikipedia/commons/thumb/3/32/ABO_blood_type.svg/2000px-ABO_blood_type.svg.png

Human blood types are determined by the presence of proteins on

the surface of red blood cells. The blood types of parents’ offspring

can be predicted using monohybrid Punnett squares.

Applications


Key Terms

Blood Type

IB BIO – 3.4 23

http://yellowbicyclestudio.com/Table%207-2.jpg

Blood Type Genotypes

There are four blood types in humans: A, B, AB and O. The

genotype for each is shown in the table below. Each allele is

represented as an I with a superscript or i (absence of protein).

Applications


Key Terms

Blood Type

IB BIO – 3.4 24Determining Blood Type – Example 1

Punnett grids for blood types are used the same way as other

monohybrid crosses. For example, this grid shows the results of

crossing two AB individuals:

IAIB x IAIB

IA IB

IA

IB

Applications


Key Terms

Blood Type


Punnett grids for blood types are used the same way as other

monohybrid crosses. For example, this grid shows the results of

crossing two AB individuals:

IAIB x IAIB

Genotypes:

- 50% IAIB

- 25% IAIA

- 25% IBIB

Phenotypes:

- 50% AB

- 25% A

- 25% B

IA IB

IA IAIA IAIB

IB IAIB IBIB

Applications


Key Terms

Blood Type


If a heterozygous Type A male mates with a heterozygous Type B

female, what percentage of the offspring will have Type O blood?

IAi x IBi

IB i

IA

i

Applications


Key Terms

Blood Type


If a heterozygous Type A male mates with a heterozygous Type B

female, what percentage of the offspring will have Type O blood?

IAi x IBi

Genotypes:

- 25% IAIB

- 25% IAi

- 25% IBi

- 25% ii

Phenotypes:

- 25% AB

- 25% A

- 25% B

- 25% O

IB i

IA IAIB IAi

i IBi ii

VID

EO

SIB BIO – 3.4 28

• Learn Biology: How to Set Up a Punnett Square

• SciShow: What are Blood Types

• TedEd: Why Do Blood Types Matter

https://www.youtube.com/watch?v=prkHKjfUmMs

https://www.youtube.com/watch?v=ttjn1jVACk8

https://www.youtube.com/watch?v=xfZhb6lmxjk

REVIE

WIB BIO – 3.4 29

1. Outline the use of Punnett Squares in predicting

the outcomes of monohybrid crosses.

2. If wrinkled pea plant (Ww) is crossed with a

smooth pea plant (ww), what percentage of the

offspring would be smooth.

3. If a Type O woman mated with a Type AB male,

what percentage of their offspring would have:

- Type O Blood?

- Type AB Blood?

- Type A Blood?

3.4 – C –Diseases & Sex-Linkage

Understandings

U6: Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some diseases are due to dominant or co-dominant alleles.

U8: Many genetic diseases have been identified in humans but most are very rare.

IB BIO – 3.4 31

http://www.institut-biotherapies.fr/wp-content/uploads/2013/01/Exp_transmission_ang.jpg

Genetic diseases are disorders that are caused by errors in

the genome. Most result from recessive alleles on the autosomal

chromosomes (1-22), though some are the result of dominance.

Many diseases have been found in humans, but most are very rare.

Improving genetic techniques are allowing scientistics to identify and

study more.

Applications

A3: Inheritance of cystic fibrosisand Huntington’s disease.

Key Terms

Cystic Fibrosis

IB BIO – 3.4 32

http://learn.genetics.utah.edu/content/disorders/singlegene/cf/images/cf-channel.jpg

Cystic fibrosis is a genetic

diseases that results from

recessive allele on

chromosome #7.

The allele produces Cl- ion

channels that increases

chloride levels in sweat and

decreases levels in mucus.

This interferes with osmosis,

which causes a buildup of

thick mucus outside of the cell

membranes.

Applications


Key Terms

Cystic Fibrosis

IB BIO – 3.4 33

http://learn.genetics.utah.edu/content/disorders/singlegene/cf/images/cf-channel.jpg

Sticky mucus builds up in

the lungs, which causes:

• Frequent infections

• Trouble Breathing

The pancreatic duct is also

blocked, which causes:

• Trouble digesting food

• Abnormal pancreas

activity/function

Applications


Key Terms

Cystic Fibrosis

IB BIO – 3.4 34

http://i0.wp.com/beatingpancreatitis.com/wp-content/uploads/2015/08/cystic-fibrosis-chronic-pancreas-inflammation.jpg

Applications


Key Terms

Cystic Fibrosis

IB BIO – 3.4 35

https://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Autorecessive.svg

Since cystic fibrosis is an

autosomal recessive disease,

Punnett grids can be used to

determine how the trait will pass

from parent to offspring.

Chances of inheriting the

disease are not related to sex.

Applications

A3: Inheritance of cystic fibrosis and Huntington’s disease.

Key Terms

Huntington’s Disease

IB BIO – 3.4 36

http://hdsa.org/wp-content/themes/hdsa/images/img_HD2.png

Huntington’s disease (HD) is a genetic disease caused by a

dominant allele on chromosome #4. Because the allele is dominant,

any individual who has even one copy of it will be affected.

Applications


Key Terms


IB BIO – 3.4 37

http://healthlifemedia.com/healthy/wp-content/uploads/2016/09/HD-n-Normal-Brain.jpg

The HD allele causes degenerative changes in the brain, which

typically starts between ages 30-50. Eventually, affected individuals

require nursing care and succumb to infectious diseases.

Punnett grids like the one here can be used to predict the likelihood

of parents passing on Huntington’s disease. Like cystic fibrosis,

inheritance of the condition is independent of sex.Applications


Key Terms


IB BIO – 3.4 38

http://www.passmyexams.co.uk/GCSE/biology/images/inheritance-chart-huntingtons.jpg

Understandings

U7: Some genetic diseases are sex-linked. The pattern of inheritance is different with sex-linked genes due to their location on sex chromosomes.

Key Terms

Sex-linked

IB BIO – 3.4 39

https://amasianv.files.wordpress.com/2012/08/sex-chromosomes1.jpg

Other genetic diseases can be

linked to sex, which means the

associated alleles are located on

the sex chromosomes (23).

As a result, the sex of offspring

can determine the likelihood of

inheriting these disease.

Two common examples include:

• Red-Green Color

Blindness

• Hemophilia

Understandings

U7: Some genetic diseases are sex-linked. The pattern of inheritance is different with sex-linked genes due to their location on sex chromosomes.

Key Terms

Sex-linked

IB BIO – 3.4 40

https://amasianv.files.wordpress.com/2012/08/sex-chromosomes1.jpg

Punnett grids can be used to determine the inheritance of sex-

linked traits. The sex chromosomes of the parents are used instead

of autosomal alleles (male = XX, female = XY). The general setup

is shown here:

X X

X XX XX

Y XY XY

Applications

A2: Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Key Terms

Red-Green Colour Blindness

IB BIO – 3.4 41

https://upload.wikimedia.org/wikipedia/commons/thumb/c/c7/X-linked_recessive.svg/

Red-green color blindness is a

sex-linked condition caused by a

recessive allele on the X

chromosome.

Since males have only one X,

they are more likely to be

affected than women, who have

two alleles for each X-linked

gene.

Applications

A2: Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Key Terms


IB BIO – 3.4 42


Those with the disease have mutated genes for red or green color

receptors in the retina. As a result, they are unable to properly

distinguish the two colors.

Applications

A2: Red-green colour blindnessand hemophilia as examples of sex-linked inheritance.

Key Terms


IB BIO – 3.4 43


Sex-Linked Inheritance Example 1

If a male with color blindness mates with a carrier female, what

percentation of their sons will have the trait?

B = normal

b = color blind

XBXb x XbY

Sons:

- 50% XBY (normal)

- 50% XbY (color blind)

Daughters:

- 50% XBXb (carrier)

- 50% XbXb (color blind)

Xb Y

XB XBXb XBY

Xb XbXb XbY

Applications

A2: Red-green colour blindness and hemophiliaas examples of sex-linked inheritance.

Key Terms

Hemophilia

IB BIO – 3.4 44

https://ghr.nlm.nih.gov/art/large/impaired-blood-clotting-in-hemophilia.jpeg

Hemophilia is another genetic disease caused by a recessive allele

on the X-chromosome. The disease prevents the ability to form

Factor VIII, which is vital for blood clotting. It is life-threatening.

Applications


Key Terms

Hemophilia

IB BIO – 3.4 45

http://www.koate-dviusa.com/filebin/images/patient/replacement-therapy.jpg

Individuals with this disorder typically have a life expectancy of

about 10 years if left untreated. Treatment involves infusing Factor

VIII isolated from donor blood sources.

Applications


Key Terms

Hemophilia

IB BIO – 3.4 46



If a female with a hemophilia mates with a normal male, what

percentage of their daughters will have the trait?

H = normal

h = hemophilia

XhXh x XHY

Sons:

- 100% XhY (hemophiliac)

Daughters:

- 100% XHXh (carrier)

- 0% XhXh (hemophiliac)

XH Y

Xh XHXh XhY

Xh XHXh XhY

Applications


Key Terms

Hemophilia

IB BIO – 3.4 47



If a famale carrier for hemophilia mates with an affected male, what

percentage of their daughters will have the trait?

H = normal

h = hemophilia

XHXh x XhY

Sons:

- 50% XHY (normal)

- 50% XhY (hemophiliac)

Daughters:

- 50% XHXh (carrier)

- 50% XhXh (hemophiliac)

Xh Y

XH XHXh XHY

Xh XhXh XhY

REVIE

WIB BIO – 3.4 48

1. Define genetic disease.

2. Outline the inheritance of Huntington’s disease

and cystic fibrosis.

3. Define sex-linked disease.

4. Compare autosomal and sex-linked traits.

5. Outline the inheritance of hemophilia and red-green

colorblindness.

3.4 – D – Pedigrees

Skills

S3: Analysis of pedigree charts to deduce the pattern of inheritance of genetic diseases.

Key Terms

Pedigree

IB BIO – 3.4

= male = affected male I, II, III = generation

= female = affected female = mating

50

https://www.mun.ca/biology/scarr/PTC_tasting_2.gif

Pedigrees are charts that show the passing of traits through a

family. The typical conventions for constructing them are:

Skills


Key Terms

Pedigree

IB BIO – 3.4 51

https://www.mun.ca/biology/scarr/PTC_tasting_2.gif

Patterns observed in pedigrees can be used to determine the type

of disease/trait that is being studied. The typical possibilities are:

- Autosomal recessive - Autosomal dominant

- X-linked recessive - X-linked dominant

Autosomal Recessive

• Traits can skip generations

and appear later

• Males and females are

affected equally

Skills


Key Terms

Pedigree

IB BIO – 3.4 52

https://sites.google.com/site/pedigreesforpredictingtraits/_/rsrc/1353457584042/volunteer-information/Recessive_Pedigree_Cyc_Fib_Blank.PNG

Autosomal Recessive

aa

aa

Aa or AA

AaAaAaAaAa

Determine the genotypes of as many members in this pedigree as

possible. The genotypes of some members cannot be determined.

Skills


Key Terms

Pedigree

IB BIO – 3.4 53

http://moodle2.rockyview.ab.ca/pluginfile.php/64202/mod_book/chapter/25853/biology_30/images/m6/b30_m6_042_l.jpg

Autosomal Dominant

• Traits do not normally skip

generations

• Unaffected members are

homozygous recessive

• Traits affect males and

females equally

Aa aa

Aa Aa

aa

Aa

Aaaa aa

aa aa

Skills


Key Terms

Pedigree

IB BIO – 3.4 54

https://migrc.org/library/X-linkedRecessive.gif

X-linked Recessive

• Traits tend to affect males

more than females

• Unaffected males have the

normal X allele

XbXb XBY

XbYXBXb XbY XbXb

XbXbXbY XbYXbY XBXb

XBY

XBY

XBXb

Skills


Key Terms

Pedigree

IB BIO – 3.4 55

https://migrc.org/Library/X-linkedDominant.gif

X-linked Dominant

• Traits affect all individuals

that have the dominant allele

• Homozygous affected females

pass trait on to all offpsring

XbYXBXb XbY

XBY XBYXBXb XbY XbXb

XbYXbYXBXb XBXb

REVIE

WIB BIO – 3.4 56

1. Determine the type of characteristic and the

genotypes in the following pedigree:

https://migrc.org/Library/AutosomalDominant.gif

REVIE

WIB BIO – 3.4 57

2. Determine the type of characteristic and the

genotypes in the following pedigree:


3.4 – E – Genetic Mutations

Understandings

U9: Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer.

Key Terms

IB BIO – 3.4 59

http://www.yourgenome.org/sites/default/files/illustrations/diagram/dna_mutations_point_mutation_yourgenome.png

As discussed in Topic 3.1, mutations are changes in DNA that can

result in new alleles. The rate of mutation can be affected by two

types of factors: radiation & mutagenic chemicals.

Understandings


Key Terms

Radiation

IB BIO – 3.4 60

https://upload.wikimedia.org/wikipedia/commons/thumb/f/fd/DNA_UV_mutation.svg

Radiation increases the rate of mutation by adding enough energy

to cause chemical changes in DNA molecules. This includes

ultraviolet radiation, X-rays and radioactive materials.

Understandings


Key Terms

Mutagenic Chemicals

IB BIO – 3.4 61

https://upload.wikimedia.org/wikipedia/commons/thumb/f/fd/DNA_UV_mutation.svg

Mutagenic chemicals are those

that cause chemical changes to

the DNA sequence.

Where as radiation is energy,

mutagenic chemicals are made

of matter.

Such chemicales include those

found in:

• Tobacco

• Mustard gas

• Nitrous Acid

Understandings


Key Terms

IB BIO – 3.4 62

http://biology-forums.com/gallery/33_25_06_11_10_06_06.jpeg

Mutations that occur

in adult cells can

causes diseases such

as cancer, but are not

passed on to offspring.

However, mutations in

cells that develop into

gametes can be

inherited by offspring.

So, mutations in

gametes are the origin

of genetic diseases.

Applications

A4: Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl.

Key Terms

Hiroshima

IB BIO – 3.4 63

http://cbsnews1.cbsistatic.com/hub/i/2016/05/25/b4c5ee68-36a2-493b-8da9-949cce03d7a2/rtsf5h2cr.jpg

Hiroshima was one of two Japanese cities hit with a number bomb

during World War II. The explosion released radioactive isotopes

into the environment which the people were then exposed to.

Applications


Key Terms

Hiroshima

IB BIO – 3.4 64

http://hiroshima.australiandoctor.com.au/wp-content/uploads/2015/07/1950s-3318250_Getty.jpg

Most who survived the blast

died within a few months due to

the radiation exposure.

The health of survivors were

tracked for over 50 years. They

showed a higher occurrence of

tumors compared to control

populations

In the following years, there

was also an increase in

mutations, causing:

• Stillbirths

• Malformations

• Deaths

Applications


Key Terms

Chernobyl

IB BIO – 3.4 65In 1986, a nuclear power plant in Chernobyl, Ukraine released

radioactive isotopes after an explosion in its nuclear core.

https://cdn.theatlantic.com/assets/media/img/photo/2011/03/the-chernobyl-disaster-25-years-ago/c02_05010183/main_1200.jpg

Applications


Key Terms

Chernobyl

IB BIO – 3.4 66Over 6 tonnes of radioactive material was released in the

atmosphere, which had widespread and severe effects:

https://upload.wikimedia.org/wikipedia/commons/thumb/2/23/Chernobyl_radiation_map_1996.svg

• 4 km2 of downwind forest

browned and died

• Local cattle died from

damaged thyroids

• After humans left the

area, local wildlife thrived

nearby

• Bioaccumulation of

radioactive materials was

seen across Europe

• More than 6,000 cases of

thyroid cancer were

reported

VID

EO

SIB BIO – 3.4 67

• PBS News: Health Effects of Hiroshima and

Nagasaki Atomic Bombings Still Carefully Tracked

• Veritasium: A Walk Around Chernobyl

• Euronews: Chernobyl – 30 Years on, Health Issues

Remain

• NYT: The Animals of Chernobyl

https://www.youtube.com/watch?v=b293Ok7FLV4

https://www.youtube.com/watch?v=9DWnjcSo9J0

https://www.youtube.com/watch?v=mylDl5_jWKw

https://www.youtube.com/watch?v=TG-nwQBBfmc

REVIE

WIB BIO – 3.4 68

1. List two examples of the following:

- Mutation-causing radiation

- Mutagenic chemicals

2. Outline consequences of the following events:

- Nuclear bombing of Hiroshima

- Chernobyl Power Plant Accident

topic 3.4 - inheritance2018/08/03 · inheritance with experiments in which large numbers of pea...

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