Genetics in Harry Potter’s World

• Phenotypes & Genotypes• Dominant & Recessive Traits• Punnett Square

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Genetics in Harry Potter?

• What types of inherited genetic traits are described in the Harry Potter series?

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Inherited Physical Traitsin Harry Potter

"All the Weasleys have red hair, freckles, and more children than they can afford." -- Draco Malfoy (Sorcerers Stone, Ch.6)

He was almost twice as tall as a normal man and at least five times as wide. (Sorcerer’s Stone, Ch.1)

Harry had a thin face, knobby knees, black hair, and bright green eyes. (Sorcerer’s Stone, Ch.1)

A pale boy with a pointed face and white-blond hair, Draco greatly resembled his father. His mother was blonde too... (Goblet of Fire, Ch.8)

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Applying Genetics to the Harry Potter Characters

• What are some phenotypes (observable traits) described in the four excerpts from the Harry Potter books?

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Applying Genetics to the Harry Potter Characters

• What are some phenotypes (observable traits) described in the four excerpts from the Harry Potter books? – Freckles– Hair color– Eye color– Height

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Applying Genetics to the Harry Potter Characters

• A genetic trait can be described in two ways:– Phenotypes are observable traits resulting

from how one’s genes are expressed. Ex., hair color, a talent, sickle cell disease, etc.

– A Genotype consists of two letters that represent a gene’s allele pair that results in a phenotype.

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Example: Freckles• Two possible phenotypes for freckles are:

– Has Freckles (observable)– No freckles (observable)

• A genotype for freckles is indicated by two alleles in the freckle gene. The possible alleles using the first letter of the trait “f” are:– F (dominant) = Has Freckles – f (recessive) = No freckles

Question: Using F and f, what are possible genotypes of the allele pair for freckles?

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Freckles: Genotypes & Phenotypes

Question: Using F and f, what are possible genotypes of the allele pair for freckles?

Genotype Phenotype (alleles inherited from parents) (physical appearance)

F F ====== has frecklesF f ====== has frecklesf f ====== no freckles

One dominant allele (F) is sufficient for its trait (has freckles) to be observable, but both alleles have to be recessive (f) for the recessive trait (no freckles) to be observable. 8

Freckles: Genotypes & Phenotypes

Question: Which genotypes are heterozygous and homozygous?

Genotype purebred or hybrid?

F F ====== homozygous F f ====== heterozygousf f ====== homozygous

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Example: Red Hair• Red hair color is recessive to brown color. One

way to describe the hair color alleles are: – Red hair = b (recessive)– Brown hair = B (dominant)

Question: Using b (red hair) and B (brown hair) alleles, what possible genotypes of the allele pair are there? Genotype (allele pair) Phenotype

(appearance)

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Example: Red HairQuestion: Using B (brown hair) and b (red hair) alleles, what possible genotypes of the allele pair are there? Genotype (allele pair) Phenotype

(appearance)

BB ====== brown hairBb ====== brown hairbb ====== red hair

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Example: Red HairQuestion: Which genotypes are homozygous(purebred) and which ones are heterozygous(hybrid)? Genotype (allele pair) Purebred or

Hybrid?BB ======Bb ======bb ======

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Example: Red HairQuestion: Which genotypes are homozygous(purebred) and which ones are heterozygous(hybrid)? Genotype (allele pair) Purebred or

Hybrid?BB ====== PurebredBb ====== Hybridbb ====== Purebred

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Harry Potter and the

Recessive AlleleHow Are Wizards

Made?

How Are Wizards Made?

• Being a wizard or a muggle is all decided by genetics

• All humans including wizards receive one allele from each parent

How Are Wizards Made?

• The allele for wizarding ability is m

• Wizards have the alleles mm

How Are Wizards Made?

• The allele for muggleness is M

• Muggles have the alleles Mm or MM

• M is dominant to m so you can only be a wizard if you have no M allele

The Malfoys

Lucius Malfoy (mm)

Narcissa Malfoy (mm)

Draco Malfoy( )

The Malfoys are a ‘pure blood’ familyAll their ancestors are wizards so they must have the alleles mm

mm

Lily Potter (mm)

James Potter (mm)

Harry Potter (WW)

Both Harry’s parents had magical ability so they must both have been mmThey passed these alleles on to Harry

The Potters

mm

The Weasleys are pure blood wizards so they all have the alleles mm

Hermione is a powerful witch so she must be mm

Both her parents are muggles so they must be Mm so they can give her a m allele each

Mm Mm

mm

Tom Riddle is a ‘half blood’. His mother was a witch (mm) and his father was a muggleHis father must have had the alleles Mm so he could give him the other m allele

mm Mm

mm

Filch is a ‘squib’

Both his parents are mm so he should be too because he can’t get an M allele from either parent but he can’t do any magic

This means he has a mutation so his wizarding powers don’t work or the man he thinks is his father isn’t really and his mother had an affair with a muggle!

What wizarding alleles would Ron and Hermione’s children have?

Ron (mm)

Hermione (mm)

Children

( )mm

Ron

m m

Hermione

m

m

Their children could only get the m allele from both parents so they would all be wizards.

mm mm

mm mm

What wizarding alleles would Ginny and Dudley’s children have?

If Dudley is Mm

Ginny mm

Dudley Mm

Children

WW or mMMm m m

Dudley

m M

Ginny

m

m

Half of their children would be likely to get the m allele from both parents so they would be wizards.The other half would be likely to get an M allele from Dudley and would be muggles.

m m

m m

M m

M m

What wizarding alleles would Ginny and Dudley’s children have?

If Dudley is MM

Ginny mm

Dudley MM

Children

WMm M

Dudley

M M

Ginnym WM WM

m WM WM

Their children would get the m allele from Ginny and the M allele from Dudley so they would all be muggles.

m M m M

m M m M

What wizarding alleles would you

expect Hermione’s brothers and sisters to have?

Mr Granger

m M

Mrs Granger

m WW WM

M WM MM

The Granger’s children have a one in four chance of getting m alleles from both parents and having magical ability.They also have a one in four chance of getting M alleles from both parents and being a muggle. They could also get only one m from their mother or father and still be a Muggle.

m M

m M

m m

M M