Transcript Breeding Corn for Two Traits

Breeding Corn for Two Traits
SEPUP Activity 6
• When farmers breed plants, they often are trying
to produce plants with more than one new &
specific trait. The more traits they try to introduce,
the more complicated the breeding becomes. In
Activity 4, you considered the heredity of corn of
one trait: kernel color (purple vs. yellow).
• In this activity, you will explore patterns of
heredity for TWO traits: kernel color and texture.
You will examine the results of a cross between
two purple smooth-kernelled corn plants. This
type of cross is referred to a DIHYBRID cross. You
will complete Punnett squares to predict the
heredity of these two traits & compare the
predicted with the actual results.
Challenge: How do
scientists predict the
results of crossing corn for
two kernel characteristics:
color & texture?
Suppose that in rabbits black hair (B) is dominant over
brown hair (b), and brown eyes (E) are dominant over blue
eyes (e). We want to investigate the probability of these
alleles for these two traits being inherited together.
The father is heterozygous for black hair and brown eyes
and the mother is homozygous recessive for both traits.
What percent of offspring could be expected to have blonde
hair and blue eyes?
Cross
gametes father can produce
__________ X __________
gametes mother can produce
gametes father can produce
gametes mother can produce
• With your partner, READ your procedure &
FOLLOW the instructions!!
When should you get a STAMP??
• After Step 2
• After Step 5
• After Step 9
• After Step 12
• After Step 15 (Obtain “Golden Rice” reading & fill
out your Case Study chart!)
• Answer AQs 1-3 in your NB & get a STAMP!
That’s 6 STAMPS, ya’ll!
Now grab a practice WS, ya hear?! 
Ear C
• Is this what YOU got?
• Ear C  9 purple smooth: 3 purple wrinkled: 3
yellow smooth: 1 yellow wrinkled
Ear D  1 purple smooth: 1 purple wrinkled: 1 yellow
smooth: 1 yellow wrinkled
Ear D
AQ #1
• Compare the Punnett squares you constructed in
Activity 4, “Breeding Corn”, with the Punnett
squares you constructed in this activity…
• A) How did you need to change the Punnett square
to consider two traits?
• 16 squares because of 4 possible allele combo
• B) How would you need to change the Punnett
square if you were to consider three traits?
• 8 possible allele combos = 8x8 = 64 squares
AQ #2
• Use the terms below to describe the information
given in the Punnett square.
A) Genotype
B) Phenotype
C) Offspring
D) Allele
AQ #3
• In what ways might the planting & consumption of
“golden rice” affect the sustainability of a
community? Discuss it in terms of all three pillars
of sustainability: economic, social, &
environmental.
• Golden Rice 2 may contribute to economic
sustainability if it is donated where it is needed, if
it provides enough beta-carotene to be of
nutritional value, and if the farmers don’t have to
buy the seed. If not donated, it may be too
expensive to grow.
AQ #3 continued…
• The social benefit is that it provides the necessary
beta-carotene, it would combat malnutrition. But
leafy, green vegetables might be a more
sustainable answer if they grow well, are as low in
cost, & people will eat them. Leafy greens also
provide more nutrients than beta-carotene. Also,
if golden rice produces health side effects, or if it
cross-pollinates other crops, it could be
environmentally unsustainable.