Transcript document

Harry Potter
and the
recessive
characteristic
Wizards and muggles, its in the genes
Wizard or muggle?
chromosomes
Being a wizard or a muggle
depends on genetics
gene
Characteristics are determined
by genes that are found on
chromosomes
Individuals have two sets of
chromosomes, one set from the
mother the other set from the
father
Therefore for a particular gene
each individual will have two
copies, one from the mother and
one from the father
from father
from mother
Wizard or muggle?
Genes can have different forms
called alleles, eg wizard allele or
muggle allele
The muggle allele is assigned
the letter ‘M’ and the wizard
allele is assigned ‘m’
It is this combination that
determines whether you are a
wizard or a muggle
To be a wizard you must have
mm
A muggle can have MM or Mm
Wizard allele
(m)
Muggle allele
(M)
Wizard or muggle?
The
Malfoys
Narcissa Malfoy
Lucius Malfoy
Draco
Malfoy
(mm)
(mm)
(mm)
The Malfoys are a “pure-blood” family
All their ancestors are wizards and therefore they only have mm
Wizard or muggle?
The
Potters
Lily Potter
(mm)
James Potter
(mm)
Harry Potter
(mm)
Both Harry’s parents had magical ability, so they must both have been mm
Harry will have received an ‘m’ from each parent
Wizard or muggle?
The Weasleys
They are all pure-bloods so they all have mm and are wizards
Wizard or muggle?
Hermione is a witch with
powerful magical abilities but
she does not come from a
pure-blood family
Neither of her parents had
magical abilities
What were her parents’ genes?
They must have both been Mm
Mm
mm
Mm
Hermione Granger
(mm)
Wizard or muggle?
Tom riddle is “half-blood”
His mother had magical
abilities but his father was a
muggle
What combination of alleles
must Tom’s father have?
father
mother
Mm
mm
mm
Tom Riddle (mm)
Wizard or muggle?
Filch is a “squib”
Both his parents were wizards and
therefore mm
This means that Filch must also be mm but
he has no magical abilities
Why is this so?
One possibility is that he has a mutation
that has resulted in the genes not working
Another possibility is that some
environmental factor has affected his
wizard genes working
Or is his father really his father? Hmmm…
Argus Filch (mm)
Wizard or not?
Wizard or muggle?
What if Ron and Hermione got together?
What sort of children would they have?
Hermione
(mm)
Ron
(mm)
children
(mm)
Wizard or muggle?
We can use a punnet square to
predict the characteristics of
the next generation (offspring)
Ron (mm)
The alleles of each parent are
placed on the sides
All the different
combinations are worked out
Remember only one allele is
passed on, but it is totally
random and each has the
same chance
Hermione
(mm)
m
m
m
mm
mm
m
mm
mm
All children must be mm!
Wizard or muggle?
Some terminology
GENOTYPE is the combination of alleles eg Mm or mm or MM
PHENOTYPE is the characteristic that we observe eg muggle or wizard
HOMOZYGOUS is when both the alleles are the same eg MM or mm
HETEROZYGOUS is when the two alleles are different eg Mm
PURE-BREED is another word for homozygous
HYBRID is another word for heterozygous
DOMINANT is the trait you see when either type of allele is presentmuggle
RECESSIVE is the trait you see only when both alleles are the same typewizard
Wizard or muggle?
What if Ginny and Dudley got together? What would their children be like?
Dudley is related to Harry but is definitely not a wizard. He is homozygous.
Ginny Weasley
(mm)
children
(?)
Dudley Dursley
(MM)
Wizard or muggle?
Ginny will only be able to pass on ‘m’
Dudley will only be able to pass on ‘M’
Dudley (MM)
Ginny
(mm)
M
M
m
Mm
Mm
m
Mm
Mm
All children (100%) will be
heterozygous and muggles!
Wizard or muggle?
What wizarding alleles would you expect Hermione’s brothers and sisters to
have?
Remember Hermione is a “muggle-born”. What must her parents have been?
They both must have been heterozygous.
Mr Granger (Mm)
M
Mrs Granger
(Mm)
M MM
m
Mm
m
Mm
mm
¾ (75% chance) would be a muggle
¼ (25% chance) would be a wizard