Name
_ ________________________________Period
_ _______Lab
#
_ ________
D ate
_ ________________
Human Karyotype & Pedigree Analysis
Introduction:
Each
s pecies
h as
a
c haracteristic
n umber
o f
c hromosomes;
f or
e xample,
c orn
c ells
h ave
2 0
chromosomes,
m ouse
c ells
h ave
4 0
c hromosomes,
a nd
h uman
c ells
h ave
4 6
c hromosomes.
I n
o rder
t o
v iew
the
c hromosomes
s o
t hat
t hey
m ay
b e
c ounted,
a
c ell
w ill
b e
a llowed
t o
r eproduce
a nd
c olchicine
i s
a dded
to
s top
t he
c ell
d ivision
d uring
m etaphase.
T he
r esulting
c ells
a re
p laced
i n
a
h ypotonic
s olution
t hat
c auses
the
c ell
m embranes
t o
r upture.
T he
c hromosomes
a re
s tained
a nd
p hotographed.
T he
c hromosomes
m ay
then
b e
c ut
o ut
o f
t he
p hotograph
a nd
a rranged
b y
h omologous
p airs.
T he
r esulting
d isplay
i s
c alled
a
karyotype.
Part 1: Typical Karyotype
The
n ormal
h uman
k aryotype
i s
c omposed
o f
s even
g roups
o f
c hromosomes
( A
–
G )
p lus
t he
s ex
chromosomes
( X
a nd
Y ).
T he
c hromosomes
a re
g rouped
a ccording
t o
s ize,
p osition
o f
t he
c entromere
a nd
the
c haracteristic
b anding
p attern.
T he
f irst
s even
g roups
a re
c alled
t he
a utosomes
w hile
t he
l arger
X
a nd
smaller
Y
c hromosomes
a re
c alled
t he
s ex
c hromosomes.
Observe
t he
n ormal
h uman
k aryotype
c hart
f ound
i n
F IGURE
I .
Figure I - Human Karyotype Chart
1.
What
i s
t he
t otal
n umber
o f
chromosomes
f ound
i n
t his
c ell?
2.
How
m any
a utosomal
c hromosome
pairs
a re
v isible
i n
t he
k aryotype?
3.
What
i s
t he
s ex
o f
t he
i ndividual?
4.
Which
p air
i s
n ot
g iven
a
n umber?
W hy?
5. In
m any
k aryotype
c harts,
t he
X
c hromosome
i s
p laced
i n
t he
C
g roup
a nd
t he
Y
c hromosome
a t
t he
e nd
o f
r ow
4 .
S uggest
a
r eason
w hy
t his
i s
d one.
6. Could
2
i ndividuals
h ave
t he
s ame
k aryotype?
E xplain
w hy
o r
w hy
n ot.