Let’s Review- Harry Potter Genetics

Let’s Review- Harry Potter Genetics

http://www.youtube.com/watch?v=hakhExBwiR0&feature=related&safety_mode=true&persist_safety_mode=1&safe=active

Question 1

• Harry has dark brown hair like his father, but his mom had red hair. Using the genotypes of B and b, what possible genotypes does each of the Potters have?

• The phenotypes of the Potters are:

– James Potter-

– Lily Potter-

– Harry Potter-

Using the genotypes of BB, Bb, bb, what are possible genotypes for Harry’s parents?

Mom could be (she has red hair)

Dad could be (he has dark brown hair)

Mom could be bbDad could be BB or Bb

Given the punnet squares for the parents, the only possible genotype for Harry is Bb

Question 2: Harry marries Ginny who has red hair. What are the possible Genotypes of their children’s hair?

First: what are the genotypes for Harry and Ginny’s hair color?

Harry is: BbGinny is: bb

Given the genotypes of Bb and bb, we can fill in the Punnet Square

• Bb Bb

• bb bb

Their children have a 50% chance of having red hair or brown hair

How can Harry help us learn about Dihybrid Squares?

Dihybrid squares are punnet squares that look to compare 2 traits and see

how they could be inherited

Keep in mind that the traits do not have to be inherited together Remember the Law of Independent Assortment

Just because Harry has brown hair does not mean he will have magic

Just because Ginny has red hair doesn’t mean that she will magic

So let’s look at the possible genes for their children!

They have 3: Lily Luna, James Sirius and Albus Severus

Let’s review the genes for Muggles , Magic, Brown hair and Red hair

M= mugglenessm= magic abilityB = brown hair

b= red hair

We have already determined the phenotypes for Harry and Ginny

Harry is mm for magic and Bb for brown hair… or mmBb

Ginny is mm for magic and bb for red hair….or mmbb

To figure out what their kids could look like, we must do a dihybrid cross

• Harry is mmBb• Factor out the possibilities

• mmBb

mB

Harry can give off the following traits:1. Take the little m and put it with the B (this is one possibility)



• mmBb

mB mb

Harry can give off the following traits:1. Take the little m and put it with

the B (this is one possibility)2. Take the little m and put it with

the little b



• mmBb

mB mb mB

Harry can give off the following traits:1. Take the little m and put it with

the B (this is one possibility)2. Take the little m and put it with

the little b3. Go to the second little m and put

it with B



• mmBb

mB mb mB mb

Harry can give off the following traits:1. Take the little m and

put it with the B (this is one possibility)

2. Take the little m and put it with the little b

3. Go to the second little m and put it with B

4. Finally take the m and put it with the b

We do this because we must “factor” all the possibilities


• Ginny is mmbb• Factor out the possibilities

• mmbb

mb

Ginny can give off the following traits:1. Take the little m and put it with the b (this is one possibility)


• Ginny is mmbb• Factor out the possibilities

• mmbb

mb mb mb mb

Ginny can give off the following traits:1. Take the little m and

put it with the b (this is one possibility)

2. Take the little m and put it with the little b

3. Go to the second little m and put it with b

4. Finally take the m and put it with the b.

Ginny can only give recessive genes

Now let’s add a Punnet square! This one must be 16 squares to account for every possibility

If Harry had mB, mb, mB, mb to give we must place it at the top to account for his genes

• mB mb mB mb

If Ginny had mb, mb, mb, mb to give we must place it on the sides to account for her genes

• mB mb mB mb

mbmb

mbmb

Now let’s factor all these together!

• mB mb mB mb

mb mmBb mmbb mmBb mmbbmb mmBb mmbb mmBb mmbb


m

Now we need to determine the % of phenotypes

Go back to the squares and count all the possible phenotypes:We know that the following possibilities could occur:

No magic, brown hair No magic, red hair Magic, brown hair

Magic, red hair

To have no magic, there must be at least ONE big M!Are there any here?

• mB mb mB mb



m

NOPE!!!!!!

• mB mb mB mb



m

So our only possibilities are magic and brown hair and magic and red hair

• mB mb mB mb



m

To have Brown hair, there must be at least one B! How many are here?

• mB mb mB mb



m

There are 8 Magic and Brown hair

• mB mb mB mb



m

To have red hair, there must be 2 little b’s! How many are here?

• mB mb mB mb



m

There are 8 magic and red hair

• mB mb mB mb



m

So phenotypically Harry and Ginny would have possibilites of :8 magic and brown haired kidsAnd8 magic and red haired kids

Or we could say a 50% chance of each

Now we need to determine the % of genotypes

Go back to the squares and count all the possible genotypes:

Start with the first box: the genotype is mmBb. How many do you see in the whole square?

• mB mb mB mb



m

8 of them are mmBb!!

• mB mb mB mb



m

How many of them are mmbb?

• mB mb mB mb



m

There are 8 mmbb

• mB mb mB mb



m

So genotypically Harry and Ginny would have possibilities of :8 mmBbAnd8 mmbb

Or we could say a 50% chance of each

Now let’s Practice!!!!

With Harry Potter of course!!!!

Question 1: Hermione and Ron marry and have 2 kids (Rose and Hugo). What are the chances that their kids have magic and red

hair?

As determined before, what are Ron’s and Hermione’s phenotypes?

Ron is magic and red hairHermione is magic and red hair

Ron and Hermione are pure recessive, so they have the same genotype: mmbb

• mb mb mb mb

mbmb

mbmb

Now let’s factor all these together!

• mb mb mb mb

mb mmbb mmbb mmbb mmbbmb mmbb mmbb mmbb mmbb

mb mmbb mmbb mmbb mmbbmb mmbb mmbb mmbb mmbb

m

So Ron and Hermione kids, based on the Punnet square

100% will have magic and be red haired!

Question 2: Hermione gets put under a spell and marries Dudley. What are the chances their kids will have magic and red hair?

We already know the following about Hermione:

She has red hair so she must be bb

She can do magic so she must be mm

Now Dudley is a different story:

We know that he has Brown hair so he could be BB or Bb

We know that he can not do magic so he is either MM or Mm

So let’s use MMBB first for Dudley and Hermione is mmbb

• MB MB MB MB

mb MmBb MmBb MmBb MmBbmb MmBb MmBb MmBb MmBb

mb MmBb MmBb MmBb MmBbmb MmBb MmBb MmBb MmBb

m

So 100% of their kids would be

Muggles with Brown hairOr MmBb

Now let’s use MmBb for Dudley and Hermione is mmbb

• MB Mb mB mb

mb MmBb Mmbb mmBb mmbbmb MmBb Mmbb mmBb mmbb

mb MmBb Mmbb mmBb mmbbmb MmBb Mmbb mmBb mmbb

m

In this case, the kids would be

25% Muggle with brown hair (MmBb)25% Muggle with red hair

25% Magic with brown hair25% Magic with red hair (mmbb)

Documents

Let’s Review- Harry Potter Genetics