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Flashcards in Backcross Method Deck (6)
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1

What is the main objective of the Backcross Method?

Qualitative improvement, by focusing on ONE trait.

2

What is the fundamental process of the Backcross Method?

Repetitve crosses of outlying progeny with specific parent... 2nd donor parent only used once in initial cross.

3

What is the general formula for recovery of recurrent parental of selected genotype?

1 - (1/2)^(N + 1)

where N = # of backcrosses

4

Why do procedures differ in Backcross Methods?

Exact procedures depend on:

- Inheritance of trait of interest
- How trait is evaluated.

5

Discuss steps of Backcrossing a dominant gene.

1. Recurrent parent A (aa) x Donor parent B (AA) -> F1 = Aa

2. aa x F1 Aa -> BC1F1 = 1/2 Aa : 1/2 aa ... evaluate / eliminate aa!

3. aa x BC1F1-> BC2F1 = 1/2 Aa : 1/2 aa ... evaluate /eliminate aa!

... repeat ...

4. BC6F1 Aa, selfed. -> BC6F2 = 1/4 AA : 1/2 Aa : 1/4 aa ... evaluate / elimate aa!

5. Self AA's and Aa's -> BC6F2:3 rows = 1/3 AA : 2/3 segregate.

6. Bulk AA's and release!

6

Discuss steps of Backcrossing a recessive gene.

1. Recurrent parent A (AA) x Donor parent (aa) -> F1 = Aa

2. AA x F1 Aa -> BC1F1 = 1/2 Aa : 1/2 AA

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