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Odd one out...
Fertilisation
• Lesson Learning Outcomes:
Increasing Difficulty
What is independent assortment of chromosomes?
Define the term
random fertilisation
Describe how sexual
reproduction leads to
variation.
Explain why different offspring
from the same parents look different.
Harry Potter and the
Recessive Allele
How 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’ family
All their ancestors are wizards so they must have the alleles mm
mmWhat alleles will Draco have inherited?
Lily Potter (mm)
James Potter (mm)
Harry Potter (WW)
Both Harry’s parents had magical ability so they must both have been mm
They 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 how can this be?
Mm Mm
mm
Mum Dad
Hermiones parents are muggles because they both have the dominant muggle allele (M), but they also both have the recessive wizard allele (m) which is the one that has been passed on to Hermione in this case
Tom Riddle is a ‘half blood’.
His mother was a witch (mm) and his father was a muggle
What alleles must his father have had?
mm Mm
mm
MumDad
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 mm
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 1 in 4 chance of getting m alleles from both parents (mm) and having magical ability
m M
m M
m m
M M
They also have a 3 in 4 chance of getting at least one M allele (Mm or MM) and being a muggle
They also have a 2 in 4 (50%) chance of being a ‘carrier’ of the recessive wizard allele (Mm) even though they themselves are muggles
Reebops• Reebops are small worm like creatures that
live in classrooms all over the world
Reebops
• They are little worm-like creatures that have three segments on their bodies and six legs.
• Instead of having 23 pairs of chromosomes like humans they have 8 pairs of chromosomes.
• You are going to create your own reebops.
Reebops
• Mammy Reebop • Daddy Reebop
• In your pair one person is the mammy reebop (pink chromosomes) and one person is the daddy reebop (blue chromosomes)
Reebops• The features of reebops are controlled by a
number of different alleles• In your pair you have each been given a set of
reebop chromosomes (the pink ones are for the mother and the blue are for the father)
• Put both sets of chromosomes letter side face down on the table.
Sex Cells• Start by making ova:• Take it in turns to pick one chromosome from
each pair of the pink chromosomes• You have each produced an ovum• Then repeat with the blue pairs to produce
sperm
Reebops• Now each person should have an ovum and a
sperm• Mix the chromosomes up to represent fertilisation• Turn the chromosomes over• Use the chromosomes as instructions to make your
own reebop.• When you are done take a picture of it using your
phone or your friends if you haven’t got one and email it to me:
Musical TOUR
Take a tour of the reebops around the room, make a list of similarities and differences to your reebop
Can you explain why
they all look diff erent?
Genetic Cross snowballing
• Write a problem for someone else (they must have to solve it using a genetic cross diagram).
• Don’t forget to say which characteristic is dominant and which one is recessive
