1. Animal Science Breeding & Genetics
Original Power Point Created by Casey Osksa
Modified by Georgia Agricultural Education Curriculum Office
June 2002

2. Genetics Terms Heterozygous = two different types of genes (Bb)
Homozygous = two similar genes (BB)
Dominant Gene = trait overpowers others
Recessive Gene = must be accompanied with another recessive gene to express trait
Incomplete Dominance = both traits express themselves

3. Punnet Square Shorthorn Cattle R = Red W = white RW = roan
If a red bull (RR) is mated to a white cow (WW), what color will the calves be?

4. Punnet Square

5. Punnet Square
If a red bull (RR) is mated to a roan (RW) cow, what color will the calves be?

6. Punnet Square

7. Punnet Square P = horned p = polled
If a homozygous horned cow (PP) is mated to a homozygous polled bull (pp), what percent of the calves will be horned, polled?

8. Punnet Square

9. Punnet Square
If a homozygous horned cow (PP) is mated to a heterozygous horned bull (Pp), what percent of the calves will be polled?

10. Punnet Square

11. Punnet Square
Mate an Angus bull that is homozygous black and polled (BBPP) to a red shorthorn cow which is homozygous red and horned (bbpp).
What is the probability that the offspring will be black? Polled? Horned? Black and Polled?

12. Punnet Square Black = 100% Polled = 100% Horned = 0%

13. Punnet Square
Now mate two of the offspring which are heterozygous for black/red and polled/horned (BbPp)
What is the probability that the offspring will be black? Black Polled? Black Horned? Red? Red Polled? Red Horned?

14. Punnet Square How do you do a punnet square with multiple genes?
Use all possible gene combinations
BbPp = could be BP, Bp, bP,bp
4 x 4 grid

15. Punnet Square

16. Punnet Square Black = 12 out of 16 or 75%
Black Polled = 9 out of 16 or 56.25%
Black Horned = 3 out of 16 or 18.75%
Red = 4 out of 16 or 25%
Red Polled = 3 out of 16 or 18.75%
Red Horned = 1 out of 16 or 6.25%

17. Punnet Square
Mate a heterozygous bull (BbPp) to a homozygous cow (BBPP)
What are the outcomes?

18. Punnet Square

19. Punnet Square Mate a (BbPp) bull to a (BBPp) cow
what are the outcomes?

20. Punnet Square