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 __________ X __________

gametes father can produce 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) GenotypeB) PhenotypeC) OffspringD)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.