Transcript The White Tiger

The White Tiger
The Story:
People love white tigers. They have
long been rumored to exist in the jungles
of the Rewa in central India for a very
long time, but has never been confirmed.
If captured alive, people could prove they
existed. In 1959 someone finally caught a
live white tiger cub.
The first thing that they had to do
was determine if it was a new
species of tiger, or if it was an white
Bengal Tiger (Panthera tigris tigris)
which is also common in the area.
Today, we are going to take the
position of the two individuals that
found and captured the first white
tiger. Our goal is to determine if the
white tiger is a new species or if they
are just albino Bengal Tigers?
DNA Gel Electrophoresis

We got a blood sample from the captured
white tiger cub (named Mohan) and a
sample from a Bengal Tiger. We are now
ready to run a DNA gel.
1. If we are going to run a DNA gel, what 3
things must we do before we can put the
DNA in the gel?
–Extract the DNA
–Cut the DNA with an Enzyme
–Add a dye to the DNA sample
2. You try using paper gels!
Results of the DNA electrophoresis:
Known
DNA
sizes
Bengal
Tiger
White
Tiger
Cub
So we don’t have a new
species…

Bummer, right?

What would have to happen for
Mohan, the first white Bengal tiger, to
be born like this?
DNA analysis results
We sent in a DNA sample to the West
Bengal University of Animal and
Fisheries Sciences in Calcutta, West
Bengal and had them analyze it.
 They found that a different amino acid
sequence caused a different protein
to be made, which added a new allele
to the population.

– Normal Bengal tigers are TT for color
– Mohan is tt for color
Thought Question
How would we make another
white Bengal Tiger?
(Remember, we know that it is tt
for the pigment gene.)
Mate Mohan with his
offspring


Mohan (tt) vs Offspring
(Tt)
½ of the offspring will
be heterozygous
– Carriers

½ will be homozygous
recessive
– White tigers
T
t
t
Tt
tt
t
Tt
tt
And so they did…
What if we wanted to create a
tame, white Bengal Tiger?
Wild Bengal Tigers are BB and
tame Bengal Tigers are bb.
 What would you have to do in
order to get a tame, white Bengal
Tiger?

Assume we cross bbtt with
BbTt
bt
bt
bt
bt
BT
BbTt
BbTt
BbTt
BbTt
Bt
Bbtt
Bbtt
Bbtt
Bbtt
bT
bbTt
bbTt
bbTt
bbTt
bt
bbtt
bbtt
bbtt
bbtt
•So what are the odds of getting a well
behaved (bb) white (tt) tiger?