Transcript sponge bob square

Learning Target:
More Bikini Bottom Genetics II
I Can…Use Punnett square technique to
predict the distribution of traits in a dihybrid
crossings
I Will…
• Determine gametes from parents for two
traits
• Complete the steps of a dihybrid crossing
• Calculate the phenotype ratio of the
offspring
Your GENIUS is showing,
so let’s have some FUN.
Time to try a dihybrid cross!
It’s a little tricky, but you can do it;
YOU’RE READY!
.
Dihybrid Crossinheritance of two different traits.
• Law of Independent Assortment – Alleles
separate independently of each other during
meiosis gamete formation (thus appear to be
inherited separately.
It is basically the same principle as a monohybrid
Punnett square, but you must remember
•F.O.I.L – First, Outer, Inner, Last
when setting up the gametes in the beginning
For example, in snails eye stalk length and snail
slime color are genes that are not on the same
chromosome and so the alleles may or may not be
inherited together.
•Long eye stalks are dominant (E) while short
eye stalks are recessive (e)
•Pink slime is dominant (P) while clear slime is
recessive (p)
SpongeBob’s pet, Gary the Snail, is Heterozygous
for both eye stalk length and snail slime color.
Gary’s genotype is
• EePp
•
To create his gametes use F.O.I.L
1.The first gamete is made
E e P p
from the First allele of each
trait.
F
O
I
l
EP
Since there are two
traits the gamete will
have two alleles which
is haploid from the
normal four in the
original diploid cell.
E e P p
F
O
I
L
EP
2. The second
gamete is made
from the two outer
alleles.
Ep
E e P p
F
O
I
L
EP
3. The third gamete
is made from the
two inner alleles.
Ep
eP
E e P p
F
O
I
L
EP
4. The fourth
gamete is made
from the last alleles
of each trait.
Ep
eP
ep
The Punnett square grid will
now have 16 boxes instead
of 4.
Follow the same
procedure for dropping
the allele down and
bringing it across as
you did for a
monohybrid cross
except you are doing it
for 2 alleles
EP
E e P p
Ep
eP
ep
E e P p
EP
E_P_
E_P_
E_P_
E_P_
Ep
eP
ep
In gametes:
E e P p
*Keep traits
in same order
*Always
keep trait
alleles
together
*Customary
to always
place
dominate
allele of each
trait first
EP
EP
EEPP
Ep
EEPp
eP
EePP
ep
EePp
E e P p
Ep
eP
ep
E e P p
EP
E e P p
Ep
eP
ep
EP
Ep
eP
ep
EEPP
EEPp
EePP
EePp
EEPp
EEpp
EePp
Eepp
EePP
EePp
eePP
eePp
EePp
Eepp
eePp
eepp
E e P p
E e P p
Genotypes:
• EEPP
• EEPp
• EEpp
• EePP
• EePp
• Eepp
• eePP
• eePp
• eepp
Phenotype ratios
Long eye stalks & Pink snail slime – 9
Long eye stalks & Clear snail slime – 3
Short eye stalks & Pink snail slime – 3
Short eye stalks & Clear snail slime - 1
(1)
(2)
(1)
(2)
(4)
(2)
(1)
(2)
(1)
9:3:3:1